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Groups > sci.electronics.design > #451909 > unrolled thread
| Started by | "billbowden" <bperryb@bowdenshobbycircuits.info> |
|---|---|
| First post | 2017-03-14 20:18 -0800 |
| Last post | 2017-03-24 21:35 +0200 |
| Articles | 20 on this page of 301 — 34 participants |
Back to article view | Back to sci.electronics.design
Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-14 20:18 -0800
Re: Antenna ferrite loopsticks verses air core? John Robertson <spam@flippers.com> - 2017-03-14 22:21 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-14 23:43 -0700
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-15 12:27 -0800
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:19 -0700
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-15 18:51 -0800
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 20:08 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-16 00:24 -0400
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 22:17 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-16 13:04 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-15 02:48 -0400
Re: Antenna ferrite loopsticks verses air core? makolber@yahoo.com - 2017-03-15 06:35 -0700
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-15 12:46 -0800
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:22 -0700
Re: Antenna ferrite loopsticks verses air core? Mike Perkins <spam@spam.com> - 2017-03-30 01:42 +0100
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-29 18:20 -0700
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-16 08:44 +0200
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 00:17 -0700
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-17 00:58 +0200
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 16:19 -0700
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-15 13:01 -0800
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-15 17:39 -0400
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:33 -0700
Re: Antenna ferrite loopsticks verses air core? "Dave M" <dgminala@mediacombb.net> - 2017-03-15 09:40 -0500
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:26 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-15 08:25 -0700
Re: Antenna ferrite loopsticks verses air core? Tim Wescott <seemywebsite@myfooter.really> - 2017-03-15 12:38 -0500
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 17:28 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-15 17:59 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-15 18:10 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-16 08:20 -0700
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-16 09:45 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-16 10:26 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 15:47 -0700
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-16 17:15 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 17:36 -0700
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-16 18:46 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 23:45 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-17 07:30 -0700
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-17 08:28 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-17 11:38 -0400
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-17 12:21 -0700
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-17 13:08 -0800
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-18 10:32 +1100
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-17 17:10 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-17 22:31 -0400
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-18 14:53 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-18 20:38 -0400
Re: Antenna ferrite loopsticks verses air core? Jeff Liebermann <jeffl@cruzio.com> - 2017-03-18 18:10 -0700
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-18 18:39 -0700
Re: Antenna ferrite loopsticks verses air core? Jeff Liebermann <jeffl@cruzio.com> - 2017-03-19 09:53 -0700
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-19 12:27 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-18 22:11 -0400
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-19 10:41 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-17 17:13 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-17 17:28 -0700
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-18 12:21 +0200
Re: Antenna ferrite loopsticks verses air core? Allan Herriman <allanherriman@hotmail.com> - 2017-03-18 12:15 +0000
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-17 17:36 -0700
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-17 18:09 -0700
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-17 18:21 -0700
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-18 10:49 +0200
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-18 08:30 -0700
Re: Antenna ferrite loopsticks verses air core? mkolber1@gmail.com - 2017-03-18 12:49 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-18 12:57 -0700
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-18 23:48 +0200
Re: Antenna ferrite loopsticks verses air core? krw@notreal.com - 2017-03-18 20:08 -0400
Re: Antenna ferrite loopsticks verses air core? kevin93 <kevin@whitedigs.com> - 2017-03-18 13:09 -0700
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-18 04:08 -0500
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-19 12:32 +1100
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-19 10:45 -0500
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-20 11:08 +1100
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-19 22:31 -0500
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-20 16:31 +1100
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-21 01:19 -0500
Re: Antenna ferrite loopsticks verses air core? Jasen Betts <jasen@xnet.co.nz> - 2017-03-22 19:15 +0000
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-18 10:41 +1100
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-18 14:47 -0700
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-19 00:22 +0200
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-19 12:39 +1100
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-18 19:11 -0700
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-19 13:15 +1100
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-20 04:26 -0700
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-21 13:17 +1100
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-21 01:32 -0500
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-21 10:38 +0200
Re: Antenna ferrite loopsticks verses air core? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-21 02:53 -0400
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-21 01:01 -0700
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-21 12:33 +0200
Re: Antenna ferrite loopsticks verses air core? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-21 09:42 -0400
Re: Antenna ferrite loopsticks verses air core? piglet <erichpwagner@hotmail.com> - 2017-03-21 19:05 +0000
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-21 12:49 -0700
Re: Antenna ferrite loopsticks verses air core? piglet <erichpwagner@hotmail.com> - 2017-03-21 18:39 +0000
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-21 22:39 +0200
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-21 12:30 +0200
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-19 17:43 +0200
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-21 14:39 +0200
Re: Antenna ferrite loopsticks verses air core? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-21 09:46 -0400
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-17 17:31 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-17 17:46 -0700
Re: Antenna ferrite loopsticks verses air core? George Herold <gherold@teachspin.com> - 2017-03-17 18:18 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-21 09:55 -0400
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-17 07:27 -0700
Re: Antenna ferrite loopsticks verses air core? DemonicTubes <tlackie@gmail.com> - 2017-03-17 09:11 -0700
Re: Antenna ferrite loopsticks verses air core? pcdhobbs@gmail.com - 2017-03-17 11:40 -0700
Re: Antenna ferrite loopsticks verses air core? bitrex <bitrex@de.lete.earthlink.net> - 2017-03-17 12:29 -0400
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-17 12:25 -0700
Re: Antenna ferrite loopsticks verses air core? bitrex <bitrex@de.lete.earthlink.net> - 2017-03-18 16:20 -0400
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 15:41 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-16 16:14 -0700
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 16:25 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-19 11:22 -0500
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-15 21:20 -0500
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-15 23:02 -0500
Re: Antenna ferrite loopsticks verses air core? whit3rd <whit3rd@gmail.com> - 2017-03-15 22:52 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-16 02:48 -0400
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 00:10 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-16 08:21 -0500
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-16 16:10 -0700
Re: Antenna ferrite loopsticks verses air core? Bill Beaty <billb@eskimo.com> - 2017-03-16 12:12 -0700
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-16 13:06 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-16 15:39 -0500
Re: Antenna ferrite loopsticks verses air core? John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-16 19:57 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-18 21:26 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-17 09:44 -0700
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-17 17:35 -0700
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-17 18:35 -0800
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-20 09:01 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-19 08:20 -0500
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-19 15:31 -0800
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-19 19:42 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-19 19:20 -0500
Re: Antenna ferrite loopsticks verses air core? Phil Allison <pallison49@gmail.com> - 2017-03-19 17:49 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-19 20:19 -0500
Re: Antenna ferrite loopsticks verses air core? Robert Baer <robertbaer@localnet.com> - 2017-03-19 19:44 -0800
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 00:00 -0400
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-19 23:56 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 08:36 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-20 09:29 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 12:54 -0500
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 13:16 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-20 12:31 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 16:46 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 17:17 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-20 18:25 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 17:15 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 18:25 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 17:56 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-20 18:49 -0700
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-21 00:19 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-21 07:27 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-21 07:28 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-21 11:24 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-21 13:39 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-23 13:52 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-23 16:48 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-23 23:58 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-24 01:13 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-24 07:00 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-24 12:47 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-24 15:13 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-24 17:05 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-24 08:44 -0500
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-24 09:13 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-24 09:40 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-24 13:08 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-24 13:42 -0700
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-24 14:20 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-24 22:46 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-24 22:13 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 09:29 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-25 11:33 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 15:20 -0400
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-25 15:25 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 19:17 -0400
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-25 17:02 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 21:25 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 20:10 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 21:32 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 22:42 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-26 00:00 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-26 04:00 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-26 05:36 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-26 09:34 -0500
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-26 10:23 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-26 13:10 -0400
Re: Antenna ferrite loopsticks verses air core? Jasen Betts <jasen@xnet.co.nz> - 2017-03-27 09:32 +0000
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 14:44 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 16:34 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 16:12 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 17:44 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 17:08 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-25 16:00 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 18:27 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 19:31 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-25 21:21 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 23:42 -0400
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-25 17:34 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 16:34 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 17:21 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 18:27 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 17:54 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 20:55 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 20:09 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 21:28 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 21:23 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 23:25 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-21 07:54 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-21 07:57 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-21 11:54 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-21 12:21 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-21 21:40 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-21 13:27 -0400
Re: Antenna ferrite loopsticks verses air core? "billbowden" <bperryb@bowdenshobbycircuits.info> - 2017-03-20 15:41 -0800
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-20 19:13 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-20 21:18 -0400
Re: Antenna ferrite loopsticks verses air core? "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-21 04:35 -0500
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-20 11:06 +0200
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-24 10:14 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-24 13:59 -0400
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-24 13:36 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 13:49 -0400
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-25 12:30 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-25 21:39 -0400
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-26 07:35 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-26 13:15 -0400
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-27 07:46 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-27 10:59 -0400
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-27 09:22 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-27 23:47 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-28 18:15 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-28 03:42 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-28 19:07 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-28 04:35 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-28 21:58 +1100
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-28 09:42 -0500
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-28 12:51 +0300
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-28 07:23 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 13:28 -0400
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-30 00:37 +0300
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 21:02 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-28 09:57 -0500
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-28 09:05 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-28 11:27 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 13:29 -0400
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-27 14:57 +0300
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-27 07:25 -0500
Re: Antenna ferrite loopsticks verses air core? Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-27 09:47 -0700
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-27 19:51 +0300
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-27 12:21 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-27 18:54 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-28 10:16 +1100
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-27 16:58 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-27 23:33 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-28 18:18 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-28 03:48 -0400
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-28 07:28 -0700
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-28 13:41 +0300
Re: Antenna ferrite loopsticks verses air core? Jasen Betts <jasen@xnet.co.nz> - 2017-03-28 07:44 +0000
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-27 21:18 -0500
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-28 18:22 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-28 04:01 -0400
Re: Antenna ferrite loopsticks verses air core? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-28 11:04 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-28 10:58 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-28 11:13 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-28 10:12 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 13:47 -0400
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-29 14:18 -0500
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-30 00:47 +0300
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-29 19:15 -0500
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 21:40 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-29 14:26 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 23:47 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-29 10:18 +1100
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-03-29 19:12 -0500
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-29 11:49 +1100
Re: Antenna ferrite loopsticks verses air core? Jeff Liebermann <jeffl@cruzio.com> - 2017-03-29 18:21 -0700
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-29 14:19 +1100
Re: Antenna ferrite loopsticks verses air core? Jeff Liebermann <jeffl@cruzio.com> - 2017-03-29 18:01 -0700
Re: Antenna ferrite loopsticks verses air core? Ralph Barone <ralph@invalid.com> - 2017-03-30 02:35 +0000
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-03-29 14:23 +1100
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-29 23:46 -0400
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-03-30 21:40 -0700
Re: Antenna ferrite loopsticks verses air core? krw@notreal.com - 2017-03-31 20:08 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-04-02 12:59 +1000
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-04-01 23:55 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-04-02 14:36 +1000
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-04-02 01:56 -0400
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-04-02 18:11 +1000
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-04-02 07:35 -0500
Re: Antenna ferrite loopsticks verses air core? mkolber1@gmail.com - 2017-04-02 06:16 -0700
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-04-03 07:40 +1000
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-04-02 08:12 -0700
Re: Antenna ferrite loopsticks verses air core? Clifford Heath <no.spam@please.net> - 2017-04-03 08:47 +1000
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-04-02 18:39 -0700
Re: Antenna ferrite loopsticks verses air core? amdx <nojunk@knology.net> - 2017-04-02 21:22 -0500
Re: Antenna ferrite loopsticks verses air core? dagmargoodboat@yahoo.com - 2017-04-03 14:12 -0700
Re: Antenna ferrite loopsticks verses air core? rickman <gnuarm@gmail.com> - 2017-03-27 23:25 -0400
Re: Antenna ferrite loopsticks verses air core? upsidedown@downunder.com - 2017-03-28 12:58 +0300
Re: Antenna ferrite loopsticks verses air core? Joerg <news@analogconsultants.com> - 2017-03-27 07:52 -0700
Re: Antenna ferrite loopsticks verses air core? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-24 21:35 +0200
Page 11 of 16 — ← Prev page 1 … 9 10 [11] 12 13 … 16 Next page →
| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-20 18:27 -0400 |
| Message-ID | <oapkqp$su9$3@dont-email.me> |
| In reply to | #452791 |
On 3/20/2017 6:21 PM, amdx wrote: > On 3/20/2017 3:34 PM, rickman wrote: >> On 3/20/2017 2:16 PM, amdx wrote: >>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote: >>> >>> If you will look at my picture, >>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>> you will notice I put the 470 ohm (turquoise resistor) on the other side >>> of the shield, (I don't know why). >>> What affect would that have? >>> >>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote: >>>>> If you want to get fancier >>>>> and even lower input capacitance we can bootstrap the drain, too. A >>>>> bootstrapped shield for your pass-through (where you bring the input >>>>> through your metal box) would help, too. >>> >>> OK, I'd like to get fancy, but I don't understand "A bootstrapped >>> shield" for my pass through. >>> I would like to understand physically what I need to do. >> >> I have seen this done for electrometers where the concern is leakage >> current. There they call it a "guard" ring. As James says, it will >> also reduce input capacitance. >> >> I don't understand how you can bootstrap the drain though. Since it is >> connected to the positive rail, I'm not even sure what that means. >> >> >>> Here's another picture showing the input, there is 5/8" hole in the case >>> and I glued polystyrene sheet over it with the input wire coming out the >>> center. >>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg >>> Ah, here's a picture of a previous input cap, I don't use anymore, but >>> it shows the input better. >>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg >> >> This latter image doesn't look like what is used in this image. >> >> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html >> >> Was this just a temporary cap in place until you got the detail work >> done? >> > > Yes, that was a first iteration, nothing wrong with it, but it wasn't > as stable (two wires with a weights on the end) as my tiny piece of > double sided pcb. Oh, so the free hanging copper is the old cap and the thing I can't see is the PCB cap which you like better? -- Rick C
[toc] | [prev] | [next] | [standalone]
| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-20 17:54 -0500 |
| Message-ID | <oapmdg$3fu$1@dont-email.me> |
| In reply to | #452793 |
On 3/20/2017 5:27 PM, rickman wrote:
> On 3/20/2017 6:21 PM, amdx wrote:
>> On 3/20/2017 3:34 PM, rickman wrote:
>>> On 3/20/2017 2:16 PM, amdx wrote:
>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote:
>>>>
>>>> If you will look at my picture,
>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163
>>>> you will notice I put the 470 ohm (turquoise resistor) on the other
>>>> side
>>>> of the shield, (I don't know why).
>>>> What affect would that have?
>>>>
>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote:
>>>>>> If you want to get fancier
>>>>>> and even lower input capacitance we can bootstrap the drain, too. A
>>>>>> bootstrapped shield for your pass-through (where you bring the input
>>>>>> through your metal box) would help, too.
>>>>
>>>> OK, I'd like to get fancy, but I don't understand "A bootstrapped
>>>> shield" for my pass through.
>>>> I would like to understand physically what I need to do.
>>>
>>> I have seen this done for electrometers where the concern is leakage
>>> current. There they call it a "guard" ring. As James says, it will
>>> also reduce input capacitance.
>>>
>>> I don't understand how you can bootstrap the drain though. Since it is
>>> connected to the positive rail, I'm not even sure what that means.
>>>
>>>
>>>> Here's another picture showing the input, there is 5/8" hole in the
>>>> case
>>>> and I glued polystyrene sheet over it with the input wire coming out
>>>> the
>>>> center.
>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg
>>>> Ah, here's a picture of a previous input cap, I don't use anymore, but
>>>> it shows the input better.
>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg
>>>
>>> This latter image doesn't look like what is used in this image.
>>>
>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html
>>>
>>> Was this just a temporary cap in place until you got the detail work
>>> done?
>>>
>>
>> Yes, that was a first iteration, nothing wrong with it, but it wasn't
>> as stable (two wires with a weights on the end) as my tiny piece of
>> double sided pcb.
>
> Oh, so the free hanging copper is the old cap and the thing I can't see
> is the PCB cap which you like better?
>
When you say can't see, do you mean it small and your looking side on
or do you mean you didn't see a link?
> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163
btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32"
thick. PCB material is not critical. Easy enough to set size, check the
gain of your amp without the input cap, then reduce the size of your
input cap until gain equals 1.
Mikek
---
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-20 20:55 -0400 |
| Message-ID | <oaptg8$qsp$1@dont-email.me> |
| In reply to | #452796 |
On 3/20/2017 6:54 PM, amdx wrote: > On 3/20/2017 5:27 PM, rickman wrote: >> On 3/20/2017 6:21 PM, amdx wrote: >>> On 3/20/2017 3:34 PM, rickman wrote: >>>> On 3/20/2017 2:16 PM, amdx wrote: >>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote: >>>>> >>>>> If you will look at my picture, >>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>> you will notice I put the 470 ohm (turquoise resistor) on the other >>>>> side >>>>> of the shield, (I don't know why). >>>>> What affect would that have? >>>>> >>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote: >>>>>>> If you want to get fancier >>>>>>> and even lower input capacitance we can bootstrap the drain, too. A >>>>>>> bootstrapped shield for your pass-through (where you bring the input >>>>>>> through your metal box) would help, too. >>>>> >>>>> OK, I'd like to get fancy, but I don't understand "A bootstrapped >>>>> shield" for my pass through. >>>>> I would like to understand physically what I need to do. >>>> >>>> I have seen this done for electrometers where the concern is leakage >>>> current. There they call it a "guard" ring. As James says, it will >>>> also reduce input capacitance. >>>> >>>> I don't understand how you can bootstrap the drain though. Since it is >>>> connected to the positive rail, I'm not even sure what that means. >>>> >>>> >>>>> Here's another picture showing the input, there is 5/8" hole in the >>>>> case >>>>> and I glued polystyrene sheet over it with the input wire coming out >>>>> the >>>>> center. >>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg >>>>> Ah, here's a picture of a previous input cap, I don't use anymore, but >>>>> it shows the input better. >>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg >>>> >>>> This latter image doesn't look like what is used in this image. >>>> >>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html >>>> >>>> Was this just a temporary cap in place until you got the detail work >>>> done? >>>> >>> >>> Yes, that was a first iteration, nothing wrong with it, but it wasn't >>> as stable (two wires with a weights on the end) as my tiny piece of >>> double sided pcb. >> >> Oh, so the free hanging copper is the old cap and the thing I can't see >> is the PCB cap which you like better? >> > > When you say can't see, do you mean it small and your looking side on > or do you mean you didn't see a link? >> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 > > btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32" > thick. PCB material is not critical. Easy enough to set size, check the > gain of your amp without the input cap, then reduce the size of your > input cap until gain equals 1. I just meant it is small and I couldn't see what it was. Initially I thought it might be a small value ceramic cap you put in place to check out the amp before you optimized the cap. Now I realize it is a very small piece of PCB and *is* the optimized cap. I also didn't know which image was earlier and which was later. Why would you adjust the overall circuit gain by trimming the cap? The amp gain can be trimmed, no? What frequency range is this amp intended to be used for? Nearly all the stuff I've seen where Q matters is LF or MF. They use loop antennas for higher frequencies, but with too high Q the bandwidth gets so narrow even voice won't get through, just CW. Some of the antennas Kleijer uses I would think would limit the bandwidth of his circuits with Q of over 1000. If the frequencies are not so high, why not use an opamp for the final stage rather than the much more complex push-pull stage? I assume that is intended to be in essence a "power" output stage and does not otherwise contribute significantly to the characteristics of the rest of the circuit. -- Rick C
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| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-20 20:09 -0500 |
| Message-ID | <oapubf$t11$1@dont-email.me> |
| In reply to | #452815 |
On 3/20/2017 7:55 PM, rickman wrote:
> On 3/20/2017 6:54 PM, amdx wrote:
>> On 3/20/2017 5:27 PM, rickman wrote:
>>> On 3/20/2017 6:21 PM, amdx wrote:
>>>> On 3/20/2017 3:34 PM, rickman wrote:
>>>>> On 3/20/2017 2:16 PM, amdx wrote:
>>>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote:
>>>>>>
>>>>>> If you will look at my picture,
>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163
>>>>>> you will notice I put the 470 ohm (turquoise resistor) on the other
>>>>>> side
>>>>>> of the shield, (I don't know why).
>>>>>> What affect would that have?
>>>>>>
>>>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote:
>>>>>>>> If you want to get fancier
>>>>>>>> and even lower input capacitance we can bootstrap the drain,
>>>>>>>> too. A
>>>>>>>> bootstrapped shield for your pass-through (where you bring the
>>>>>>>> input
>>>>>>>> through your metal box) would help, too.
>>>>>>
>>>>>> OK, I'd like to get fancy, but I don't understand "A bootstrapped
>>>>>> shield" for my pass through.
>>>>>> I would like to understand physically what I need to do.
>>>>>
>>>>> I have seen this done for electrometers where the concern is leakage
>>>>> current. There they call it a "guard" ring. As James says, it will
>>>>> also reduce input capacitance.
>>>>>
>>>>> I don't understand how you can bootstrap the drain though. Since
>>>>> it is
>>>>> connected to the positive rail, I'm not even sure what that means.
>>>>>
>>>>>
>>>>>> Here's another picture showing the input, there is 5/8" hole in the
>>>>>> case
>>>>>> and I glued polystyrene sheet over it with the input wire coming out
>>>>>> the
>>>>>> center.
>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg
>>>>>> Ah, here's a picture of a previous input cap, I don't use anymore,
>>>>>> but
>>>>>> it shows the input better.
>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg
>>>>>
>>>>> This latter image doesn't look like what is used in this image.
>>>>>
>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html
>>>>>
>>>>> Was this just a temporary cap in place until you got the detail work
>>>>> done?
>>>>>
>>>>
>>>> Yes, that was a first iteration, nothing wrong with it, but it wasn't
>>>> as stable (two wires with a weights on the end) as my tiny piece of
>>>> double sided pcb.
>>>
>>> Oh, so the free hanging copper is the old cap and the thing I can't see
>>> is the PCB cap which you like better?
>>>
>>
>> When you say can't see, do you mean it small and your looking side on
>> or do you mean you didn't see a link?
>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163
>>
>> btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32"
>> thick. PCB material is not critical. Easy enough to set size, check the
>> gain of your amp without the input cap, then reduce the size of your
>> input cap until gain equals 1.
>
> I just meant it is small and I couldn't see what it was. Initially I
> thought it might be a small value ceramic cap you put in place to check
> out the amp before you optimized the cap. Now I realize it is a very
> small piece of PCB and *is* the optimized cap. I also didn't know which
> image was earlier and which was later.
>
> Why would you adjust the overall circuit gain by trimming the cap? The
> amp gain can be trimmed, no?
>
I'm sure the amp can be changed, but the end game was to make the input
cap small, I couldn't go much smaller.
> What frequency range is this amp intended to be used for? Nearly all
> the stuff I've seen where Q matters is LF or MF.
Kleijer says it's flat from 10kHz to 10 MHz.
> They use loop antennas
> for higher frequencies, but with too high Q the bandwidth gets so narrow
> even voice won't get through, just CW.
>
Most of the stuff I'm looking at is crystal radio, by the time you
start driving a headphone your Q gets lowered a lot. I never hear the
crystal radio guys complain about lack of bandwidth.
> Some of the antennas Kleijer uses I would think would limit the
> bandwidth of his circuits with Q of over 1000.
>
Again not a common problem, but easy to fix with a load resistor.
> If the frequencies are not so high, why not use an opamp for the final
> stage rather than the much more complex push-pull stage? I assume that
> is intended to be in essence a "power" output stage and does not
> otherwise contribute significantly to the characteristics of the rest of
> the circuit.
>
I'm sure it could be built with a couple of opamps. It is a 50 ohm
output. Could probably do better, this starts to distort at I think
8 Vpp. But I don't have any antenna that need much that headroom.
Mikek
---
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-20 21:28 -0400 |
| Message-ID | <oapve0$vh0$1@dont-email.me> |
| In reply to | #452820 |
On 3/20/2017 9:09 PM, amdx wrote: > On 3/20/2017 7:55 PM, rickman wrote: >> On 3/20/2017 6:54 PM, amdx wrote: >>> On 3/20/2017 5:27 PM, rickman wrote: >>>> On 3/20/2017 6:21 PM, amdx wrote: >>>>> On 3/20/2017 3:34 PM, rickman wrote: >>>>>> On 3/20/2017 2:16 PM, amdx wrote: >>>>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote: >>>>>>> >>>>>>> If you will look at my picture, >>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>>>> you will notice I put the 470 ohm (turquoise resistor) on the other >>>>>>> side >>>>>>> of the shield, (I don't know why). >>>>>>> What affect would that have? >>>>>>> >>>>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote: >>>>>>>>> If you want to get fancier >>>>>>>>> and even lower input capacitance we can bootstrap the drain, >>>>>>>>> too. A >>>>>>>>> bootstrapped shield for your pass-through (where you bring the >>>>>>>>> input >>>>>>>>> through your metal box) would help, too. >>>>>>> >>>>>>> OK, I'd like to get fancy, but I don't understand "A bootstrapped >>>>>>> shield" for my pass through. >>>>>>> I would like to understand physically what I need to do. >>>>>> >>>>>> I have seen this done for electrometers where the concern is leakage >>>>>> current. There they call it a "guard" ring. As James says, it will >>>>>> also reduce input capacitance. >>>>>> >>>>>> I don't understand how you can bootstrap the drain though. Since >>>>>> it is >>>>>> connected to the positive rail, I'm not even sure what that means. >>>>>> >>>>>> >>>>>>> Here's another picture showing the input, there is 5/8" hole in the >>>>>>> case >>>>>>> and I glued polystyrene sheet over it with the input wire coming out >>>>>>> the >>>>>>> center. >>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg >>>>>>> Ah, here's a picture of a previous input cap, I don't use anymore, >>>>>>> but >>>>>>> it shows the input better. >>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg >>>>>> >>>>>> This latter image doesn't look like what is used in this image. >>>>>> >>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html >>>>>> >>>>>> Was this just a temporary cap in place until you got the detail work >>>>>> done? >>>>>> >>>>> >>>>> Yes, that was a first iteration, nothing wrong with it, but it wasn't >>>>> as stable (two wires with a weights on the end) as my tiny piece of >>>>> double sided pcb. >>>> >>>> Oh, so the free hanging copper is the old cap and the thing I can't see >>>> is the PCB cap which you like better? >>>> >>> >>> When you say can't see, do you mean it small and your looking side on >>> or do you mean you didn't see a link? >>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>> >>> btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32" >>> thick. PCB material is not critical. Easy enough to set size, check the >>> gain of your amp without the input cap, then reduce the size of your >>> input cap until gain equals 1. >> >> I just meant it is small and I couldn't see what it was. Initially I >> thought it might be a small value ceramic cap you put in place to check >> out the amp before you optimized the cap. Now I realize it is a very >> small piece of PCB and *is* the optimized cap. I also didn't know which >> image was earlier and which was later. >> >> Why would you adjust the overall circuit gain by trimming the cap? The >> amp gain can be trimmed, no? >> > I'm sure the amp can be changed, but the end game was to make the input > cap small, I couldn't go much smaller. > >> What frequency range is this amp intended to be used for? Nearly all >> the stuff I've seen where Q matters is LF or MF. > > Kleijer says it's flat from 10kHz to 10 MHz. > >> They use loop antennas >> for higher frequencies, but with too high Q the bandwidth gets so narrow >> even voice won't get through, just CW. >> > Most of the stuff I'm looking at is crystal radio, by the time you > start driving a headphone your Q gets lowered a lot. I never hear the > crystal radio guys complain about lack of bandwidth. > >> Some of the antennas Kleijer uses I would think would limit the >> bandwidth of his circuits with Q of over 1000. >> > Again not a common problem, but easy to fix with a load resistor. If the headphones or load resistor limit the Q, what is the bleeping point of all that Litz wire and custom tuning capacitor stuff? I thought the whole point was to get the Q as high as possible. If you start with a Q over 1000 and end up with a few hundred, I wouldn't expect that to be distinguishable from a coil with a Q of some hundreds which is where Kleijer started in his coil investigations. >> If the frequencies are not so high, why not use an opamp for the final >> stage rather than the much more complex push-pull stage? I assume that >> is intended to be in essence a "power" output stage and does not >> otherwise contribute significantly to the characteristics of the rest of >> the circuit. >> > I'm sure it could be built with a couple of opamps. It is a 50 ohm > output. Could probably do better, this starts to distort at I think > 8 Vpp. But I don't have any antenna that need much that headroom. I designed an opamp circuit to output an 8 volt signal with a 12 volt supply into 50 ohm cable. I didn't quite get 8 volts before it starts to distort, but it was close. I believe the gain-bandwidth product of the amp was over 30 MHz, so it should do ok at 10 MHz and no gain. But then you need a little gain I guess. Opps, no, the GB was 15 MHz. -- Rick C
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| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-20 21:23 -0500 |
| Message-ID | <oaq2l6$7hj$1@dont-email.me> |
| In reply to | #452827 |
On 3/20/2017 8:28 PM, rickman wrote: > On 3/20/2017 9:09 PM, amdx wrote: >> On 3/20/2017 7:55 PM, rickman wrote: >>> On 3/20/2017 6:54 PM, amdx wrote: >>>> On 3/20/2017 5:27 PM, rickman wrote: >>>>> On 3/20/2017 6:21 PM, amdx wrote: >>>>>> On 3/20/2017 3:34 PM, rickman wrote: >>>>>>> On 3/20/2017 2:16 PM, amdx wrote: >>>>>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote: >>>>>>>> >>>>>>>> If you will look at my picture, >>>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>>>>>> >>>>>>>> you will notice I put the 470 ohm (turquoise resistor) on the other >>>>>>>> side >>>>>>>> of the shield, (I don't know why). >>>>>>>> What affect would that have? >>>>>>>> >>>>>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote: >>>>>>>>>> If you want to get fancier >>>>>>>>>> and even lower input capacitance we can bootstrap the drain, >>>>>>>>>> too. A >>>>>>>>>> bootstrapped shield for your pass-through (where you bring the >>>>>>>>>> input >>>>>>>>>> through your metal box) would help, too. >>>>>>>> >>>>>>>> OK, I'd like to get fancy, but I don't understand "A bootstrapped >>>>>>>> shield" for my pass through. >>>>>>>> I would like to understand physically what I need to do. >>>>>>> >>>>>>> I have seen this done for electrometers where the concern is leakage >>>>>>> current. There they call it a "guard" ring. As James says, it will >>>>>>> also reduce input capacitance. >>>>>>> >>>>>>> I don't understand how you can bootstrap the drain though. Since >>>>>>> it is >>>>>>> connected to the positive rail, I'm not even sure what that means. >>>>>>> >>>>>>> >>>>>>>> Here's another picture showing the input, there is 5/8" hole in the >>>>>>>> case >>>>>>>> and I glued polystyrene sheet over it with the input wire coming >>>>>>>> out >>>>>>>> the >>>>>>>> center. >>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg >>>>>>>> Ah, here's a picture of a previous input cap, I don't use anymore, >>>>>>>> but >>>>>>>> it shows the input better. >>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg >>>>>>>>> >>>>>>> >>>>>>> This latter image doesn't look like what is used in this image. >>>>>>> >>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html >>>>>>> >>>>>>> Was this just a temporary cap in place until you got the detail work >>>>>>> done? >>>>>>> >>>>>> >>>>>> Yes, that was a first iteration, nothing wrong with it, but it >>>>>> wasn't >>>>>> as stable (two wires with a weights on the end) as my tiny piece of >>>>>> double sided pcb. >>>>> >>>>> Oh, so the free hanging copper is the old cap and the thing I can't >>>>> see >>>>> is the PCB cap which you like better? >>>>> >>>> >>>> When you say can't see, do you mean it small and your looking side on >>>> or do you mean you didn't see a link? >>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>> >>>> btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32" >>>> thick. PCB material is not critical. Easy enough to set size, check the >>>> gain of your amp without the input cap, then reduce the size of your >>>> input cap until gain equals 1. >>> >>> I just meant it is small and I couldn't see what it was. Initially I >>> thought it might be a small value ceramic cap you put in place to check >>> out the amp before you optimized the cap. Now I realize it is a very >>> small piece of PCB and *is* the optimized cap. I also didn't know which >>> image was earlier and which was later. >>> >>> Why would you adjust the overall circuit gain by trimming the cap? The >>> amp gain can be trimmed, no? >>> >> I'm sure the amp can be changed, but the end game was to make the input >> cap small, I couldn't go much smaller. >> >>> What frequency range is this amp intended to be used for? Nearly all >>> the stuff I've seen where Q matters is LF or MF. >> >> Kleijer says it's flat from 10kHz to 10 MHz. >> >>> They use loop antennas >>> for higher frequencies, but with too high Q the bandwidth gets so narrow >>> even voice won't get through, just CW. >>> >> Most of the stuff I'm looking at is crystal radio, by the time you >> start driving a headphone your Q gets lowered a lot. I never hear the >> crystal radio guys complain about lack of bandwidth. >> >>> Some of the antennas Kleijer uses I would think would limit the >>> bandwidth of his circuits with Q of over 1000. >>> >> Again not a common problem, but easy to fix with a load resistor. > > If the headphones or load resistor limit the Q, what is the bleeping > point of all that Litz wire and custom tuning capacitor stuff? I > thought the whole point was to get the Q as high as possible. Yes, it is. But you still need to get the maximum power out to drive your headphones. In a perfect system, you would drop your Q by half to get maximum audio. But the diode gets involved and that I can't decipher. > If you start with a Q over 1000 and end up with a few hundred, I wouldn't > expect that to be distinguishable from a coil with a Q of some hundreds > which is where Kleijer started in his coil investigations. This is radio dxing, grab every db of signal! > > >>> If the frequencies are not so high, why not use an opamp for the final >>> stage rather than the much more complex push-pull stage? I assume that >>> is intended to be in essence a "power" output stage and does not >>> otherwise contribute significantly to the characteristics of the rest of >>> the circuit. >>> >> I'm sure it could be built with a couple of opamps. It is a 50 ohm >> output. Could probably do better, this starts to distort at I think >> 8 Vpp. But I don't have any antenna that need much that headroom. That's 8Vpp open circuit, 4Vpp loaded. > I designed an opamp circuit to output an 8 volt signal with a 12 volt > supply into 50 ohm cable. I didn't quite get 8 volts before it starts > to distort, but it was close. I believe the gain-bandwidth product of > the amp was over 30 MHz, so it should do ok at 10 MHz and no gain. But > then you need a little gain I guess. Opps, no, the GB was 15 MHz. > --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-20 23:25 -0400 |
| Message-ID | <oaq6ae$8un$1@dont-email.me> |
| In reply to | #452837 |
On 3/20/2017 10:23 PM, amdx wrote: > On 3/20/2017 8:28 PM, rickman wrote: >> On 3/20/2017 9:09 PM, amdx wrote: >>> On 3/20/2017 7:55 PM, rickman wrote: >>>> On 3/20/2017 6:54 PM, amdx wrote: >>>>> On 3/20/2017 5:27 PM, rickman wrote: >>>>>> On 3/20/2017 6:21 PM, amdx wrote: >>>>>>> On 3/20/2017 3:34 PM, rickman wrote: >>>>>>>> On 3/20/2017 2:16 PM, amdx wrote: >>>>>>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote: >>>>>>>>> >>>>>>>>> If you will look at my picture, >>>>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>>>>>>> >>>>>>>>>> >>>>>>>>> you will notice I put the 470 ohm (turquoise resistor) on the >>>>>>>>> other >>>>>>>>> side >>>>>>>>> of the shield, (I don't know why). >>>>>>>>> What affect would that have? >>>>>>>>> >>>>>>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote: >>>>>>>>>>> If you want to get fancier >>>>>>>>>>> and even lower input capacitance we can bootstrap the drain, >>>>>>>>>>> too. A >>>>>>>>>>> bootstrapped shield for your pass-through (where you bring the >>>>>>>>>>> input >>>>>>>>>>> through your metal box) would help, too. >>>>>>>>> >>>>>>>>> OK, I'd like to get fancy, but I don't understand "A bootstrapped >>>>>>>>> shield" for my pass through. >>>>>>>>> I would like to understand physically what I need to do. >>>>>>>> >>>>>>>> I have seen this done for electrometers where the concern is >>>>>>>> leakage >>>>>>>> current. There they call it a "guard" ring. As James says, it >>>>>>>> will >>>>>>>> also reduce input capacitance. >>>>>>>> >>>>>>>> I don't understand how you can bootstrap the drain though. Since >>>>>>>> it is >>>>>>>> connected to the positive rail, I'm not even sure what that means. >>>>>>>> >>>>>>>> >>>>>>>>> Here's another picture showing the input, there is 5/8" hole in >>>>>>>>> the >>>>>>>>> case >>>>>>>>> and I glued polystyrene sheet over it with the input wire coming >>>>>>>>> out >>>>>>>>> the >>>>>>>>> center. >>>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg >>>>>>>>> Ah, here's a picture of a previous input cap, I don't use anymore, >>>>>>>>> but >>>>>>>>> it shows the input better. >>>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg >>>>>>>>>> >>>>>>>>>> >>>>>>>> >>>>>>>> This latter image doesn't look like what is used in this image. >>>>>>>> >>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html >>>>>>>> >>>>>>>> Was this just a temporary cap in place until you got the detail >>>>>>>> work >>>>>>>> done? >>>>>>>> >>>>>>> >>>>>>> Yes, that was a first iteration, nothing wrong with it, but it >>>>>>> wasn't >>>>>>> as stable (two wires with a weights on the end) as my tiny piece of >>>>>>> double sided pcb. >>>>>> >>>>>> Oh, so the free hanging copper is the old cap and the thing I can't >>>>>> see >>>>>> is the PCB cap which you like better? >>>>>> >>>>> >>>>> When you say can't see, do you mean it small and your looking side on >>>>> or do you mean you didn't see a link? >>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>> >>>>> btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32" >>>>> thick. PCB material is not critical. Easy enough to set size, check >>>>> the >>>>> gain of your amp without the input cap, then reduce the size of your >>>>> input cap until gain equals 1. >>>> >>>> I just meant it is small and I couldn't see what it was. Initially I >>>> thought it might be a small value ceramic cap you put in place to check >>>> out the amp before you optimized the cap. Now I realize it is a very >>>> small piece of PCB and *is* the optimized cap. I also didn't know >>>> which >>>> image was earlier and which was later. >>>> >>>> Why would you adjust the overall circuit gain by trimming the cap? The >>>> amp gain can be trimmed, no? >>>> >>> I'm sure the amp can be changed, but the end game was to make the input >>> cap small, I couldn't go much smaller. >>> >>>> What frequency range is this amp intended to be used for? Nearly all >>>> the stuff I've seen where Q matters is LF or MF. >>> >>> Kleijer says it's flat from 10kHz to 10 MHz. >>> >>>> They use loop antennas >>>> for higher frequencies, but with too high Q the bandwidth gets so >>>> narrow >>>> even voice won't get through, just CW. >>>> >>> Most of the stuff I'm looking at is crystal radio, by the time you >>> start driving a headphone your Q gets lowered a lot. I never hear the >>> crystal radio guys complain about lack of bandwidth. >>> >>>> Some of the antennas Kleijer uses I would think would limit the >>>> bandwidth of his circuits with Q of over 1000. >>>> >>> Again not a common problem, but easy to fix with a load resistor. >> >> If the headphones or load resistor limit the Q, what is the bleeping >> point of all that Litz wire and custom tuning capacitor stuff? I >> thought the whole point was to get the Q as high as possible. > > Yes, it is. But you still need to get the maximum power out to drive > your headphones. > In a perfect system, you would drop your Q by half to get maximum > audio. But the diode gets involved and that I can't decipher. > > >> If you start with a Q over 1000 and end up with a few hundred, I >> wouldn't >> expect that to be distinguishable from a coil with a Q of some hundreds >> which is where Kleijer started in his coil investigations. > > This is radio dxing, grab every db of signal! >> >> >>>> If the frequencies are not so high, why not use an opamp for the final >>>> stage rather than the much more complex push-pull stage? I assume that >>>> is intended to be in essence a "power" output stage and does not >>>> otherwise contribute significantly to the characteristics of the >>>> rest of >>>> the circuit. >>>> >>> I'm sure it could be built with a couple of opamps. It is a 50 ohm >>> output. Could probably do better, this starts to distort at I think >>> 8 Vpp. But I don't have any antenna that need much that headroom. > > That's 8Vpp open circuit, 4Vpp loaded. Well then, eazy peazy. I used a circuit that used positive feedback to make the output impedance look higher than the resistor in the circuit. I think I used 12.5 or maybe it was just 12 and got multiplied by 4. This makes the calculation of the gain a little more complex so you would not be able to adjust the gain with a pot or anything... unless it was on an earlier stage. The middle stage with the single transistor, anything special about that? It has a connection with caps I'm not familiar with from the emitter to the input. That would be a low level of positive feedback I believe. Any idea why? >> I designed an opamp circuit to output an 8 volt signal with a 12 volt >> supply into 50 ohm cable. I didn't quite get 8 volts before it starts >> to distort, but it was close. I believe the gain-bandwidth product of >> the amp was over 30 MHz, so it should do ok at 10 MHz and no gain. But >> then you need a little gain I guess. Opps, no, the GB was 15 MHz. Wait a minute!!! That bootstrap of the input resistors won't work. The 470 ohm source resistor is there to set a bias point with the source higher than the gate. The resistors are there to set the DC voltage of the gate to ground. Perhaps a cap could be used to feed the point between the two resistors? I just realized that is the purpose of the two caps on T2 emitter to the 47 ohm resistor. It allows the resistors to set the DC operating point but bootstraps their capacitance. No? -- Rick C
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| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-21 07:54 -0500 |
| Message-ID | <oar7ko$4sc$1@dont-email.me> |
| In reply to | #452843 |
On 3/20/2017 10:25 PM, rickman wrote:
> On 3/20/2017 10:23 PM, amdx wrote:
>> On 3/20/2017 8:28 PM, rickman wrote:
>>> On 3/20/2017 9:09 PM, amdx wrote:
>>>> On 3/20/2017 7:55 PM, rickman wrote:
>>>>> On 3/20/2017 6:54 PM, amdx wrote:
>>>>>> On 3/20/2017 5:27 PM, rickman wrote:
>>>>>>> On 3/20/2017 6:21 PM, amdx wrote:
>>>>>>>> On 3/20/2017 3:34 PM, rickman wrote:
>>>>>>>>> On 3/20/2017 2:16 PM, amdx wrote:
>>>>>>>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote:
>>>>>>>>>>
>>>>>>>>>> If you will look at my picture,
>>>>>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>> you will notice I put the 470 ohm (turquoise resistor) on the
>>>>>>>>>> other
>>>>>>>>>> side
>>>>>>>>>> of the shield, (I don't know why).
>>>>>>>>>> What affect would that have?
>>>>>>>>>>
>>>>>>>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote:
>>>>>>>>>>>> If you want to get fancier
>>>>>>>>>>>> and even lower input capacitance we can bootstrap the drain,
>>>>>>>>>>>> too. A
>>>>>>>>>>>> bootstrapped shield for your pass-through (where you bring the
>>>>>>>>>>>> input
>>>>>>>>>>>> through your metal box) would help, too.
>>>>>>>>>>
>>>>>>>>>> OK, I'd like to get fancy, but I don't understand "A
>>>>>>>>>> bootstrapped
>>>>>>>>>> shield" for my pass through.
>>>>>>>>>> I would like to understand physically what I need to do.
>>>>>>>>>
>>>>>>>>> I have seen this done for electrometers where the concern is
>>>>>>>>> leakage
>>>>>>>>> current. There they call it a "guard" ring. As James says, it
>>>>>>>>> will
>>>>>>>>> also reduce input capacitance.
>>>>>>>>>
>>>>>>>>> I don't understand how you can bootstrap the drain though. Since
>>>>>>>>> it is
>>>>>>>>> connected to the positive rail, I'm not even sure what that means.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Here's another picture showing the input, there is 5/8" hole in
>>>>>>>>>> the
>>>>>>>>>> case
>>>>>>>>>> and I glued polystyrene sheet over it with the input wire coming
>>>>>>>>>> out
>>>>>>>>>> the
>>>>>>>>>> center.
>>>>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg
>>>>>>>>>> Ah, here's a picture of a previous input cap, I don't use
>>>>>>>>>> anymore,
>>>>>>>>>> but
>>>>>>>>>> it shows the input better.
>>>>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> This latter image doesn't look like what is used in this image.
>>>>>>>>>
>>>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html
>>>>>>>>>
>>>>>>>>> Was this just a temporary cap in place until you got the detail
>>>>>>>>> work
>>>>>>>>> done?
>>>>>>>>>
>>>>>>>>
>>>>>>>> Yes, that was a first iteration, nothing wrong with it, but it
>>>>>>>> wasn't
>>>>>>>> as stable (two wires with a weights on the end) as my tiny piece of
>>>>>>>> double sided pcb.
>>>>>>>
>>>>>>> Oh, so the free hanging copper is the old cap and the thing I can't
>>>>>>> see
>>>>>>> is the PCB cap which you like better?
>>>>>>>
>>>>>>
>>>>>> When you say can't see, do you mean it small and your looking
>>>>>> side on
>>>>>> or do you mean you didn't see a link?
>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163
>>>>>>
>>>>>> btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32"
>>>>>> thick. PCB material is not critical. Easy enough to set size, check
>>>>>> the
>>>>>> gain of your amp without the input cap, then reduce the size of your
>>>>>> input cap until gain equals 1.
>>>>>
>>>>> I just meant it is small and I couldn't see what it was. Initially I
>>>>> thought it might be a small value ceramic cap you put in place to
>>>>> check
>>>>> out the amp before you optimized the cap. Now I realize it is a very
>>>>> small piece of PCB and *is* the optimized cap. I also didn't know
>>>>> which
>>>>> image was earlier and which was later.
>>>>>
>>>>> Why would you adjust the overall circuit gain by trimming the cap?
>>>>> The
>>>>> amp gain can be trimmed, no?
>>>>>
>>>> I'm sure the amp can be changed, but the end game was to make the
>>>> input
>>>> cap small, I couldn't go much smaller.
>>>>
>>>>> What frequency range is this amp intended to be used for? Nearly all
>>>>> the stuff I've seen where Q matters is LF or MF.
>>>>
>>>> Kleijer says it's flat from 10kHz to 10 MHz.
>>>>
>>>>> They use loop antennas
>>>>> for higher frequencies, but with too high Q the bandwidth gets so
>>>>> narrow
>>>>> even voice won't get through, just CW.
>>>>>
>>>> Most of the stuff I'm looking at is crystal radio, by the time you
>>>> start driving a headphone your Q gets lowered a lot. I never hear the
>>>> crystal radio guys complain about lack of bandwidth.
>>>>
>>>>> Some of the antennas Kleijer uses I would think would limit the
>>>>> bandwidth of his circuits with Q of over 1000.
>>>>>
>>>> Again not a common problem, but easy to fix with a load resistor.
>>>
>>> If the headphones or load resistor limit the Q, what is the bleeping
>>> point of all that Litz wire and custom tuning capacitor stuff? I
>>> thought the whole point was to get the Q as high as possible.
>>
>> Yes, it is. But you still need to get the maximum power out to drive
>> your headphones.
>> In a perfect system, you would drop your Q by half to get maximum
>> audio. But the diode gets involved and that I can't decipher.
>>
>>
>>> If you start with a Q over 1000 and end up with a few hundred, I
>>> wouldn't
>>> expect that to be distinguishable from a coil with a Q of some hundreds
>>> which is where Kleijer started in his coil investigations.
>>
>> This is radio dxing, grab every db of signal!
>>>
>>>
>>>>> If the frequencies are not so high, why not use an opamp for the final
>>>>> stage rather than the much more complex push-pull stage? I assume
>>>>> that
>>>>> is intended to be in essence a "power" output stage and does not
>>>>> otherwise contribute significantly to the characteristics of the
>>>>> rest of
>>>>> the circuit.
>>>>>
>>>> I'm sure it could be built with a couple of opamps. It is a 50 ohm
>>>> output. Could probably do better, this starts to distort at I think
>>>> 8 Vpp. But I don't have any antenna that need much that headroom.
>>
>> That's 8Vpp open circuit, 4Vpp loaded.
>
> Well then, eazy peazy. I used a circuit that used positive feedback to
> make the output impedance look higher than the resistor in the circuit.
> I think I used 12.5 or maybe it was just 12 and got multiplied by 4.
> This makes the calculation of the gain a little more complex so you
> would not be able to adjust the gain with a pot or anything... unless it
> was on an earlier stage.
>
> The middle stage with the single transistor, anything special about
> that? It has a connection with caps I'm not familiar with from the
> emitter to the input. That would be a low level of positive feedback I
> believe. Any idea why?
>
Hey I'm a semi-retired shrimp seller with a little bit of technical
skill. I did a good job of replicating the circuit, I didn't design it.
I can only explain operation on a simple level. If I had more knowledge
I would have corrected the distortion at increased input levels.
I suspect a good analog engineer would have done a lot of things
different to reach the goal of high input impedance, 50 ohm output. On
the other hand Kleijer built a working circuit and later went back and
built an improved second version. I follow the crystal radio community
and have not heard of anyone else that built the circuit, it's a shame
because it is a very useful piece of equipment for experimenting with
high Q LC circuits.
I hope to take dagmar's design and improve it further.
>>> I designed an opamp circuit to output an 8 volt signal with a 12 volt
>>> supply into 50 ohm cable. I didn't quite get 8 volts before it starts
>>> to distort, but it was close. I believe the gain-bandwidth product of
>>> the amp was over 30 MHz, so it should do ok at 10 MHz and no gain. But
>>> then you need a little gain I guess. Opps, no, the GB was 15 MHz.
>
> Wait a minute!!! That bootstrap of the input resistors won't work. The
> 470 ohm source resistor is there to set a bias point with the source
> higher than the gate. The resistors are there to set the DC voltage of
> the gate to ground. Perhaps a cap could be used to feed the point
> between the two resistors?
>
> I just realized that is the purpose of the two caps on T2 emitter to the
> 47 ohm resistor. It allows the resistors to set the DC operating point
> but bootstraps their capacitance. No?
>
??
I have looked for a data sheet on the BF256C, all I can find is very
limited info, Anyone find a data sheet with the device capacitances?
Mikek
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| From | dagmargoodboat@yahoo.com |
|---|---|
| Date | 2017-03-21 07:57 -0700 |
| Message-ID | <84644042-5305-49bd-9e87-ba7f2bc28824@googlegroups.com> |
| In reply to | #452879 |
On Tuesday, March 21, 2017 at 8:54:35 AM UTC-4, amdx wrote: > On 3/20/2017 10:25 PM, rickman wrote: > > On 3/20/2017 10:23 PM, amdx wrote: > >> On 3/20/2017 8:28 PM, rickman wrote: > >>> On 3/20/2017 9:09 PM, amdx wrote: > >>>> I'm sure it could be built with a couple of opamps. It is a 50 ohm > >>>> output. Could probably do better, this starts to distort at I think > >>>> 8 Vpp. But I don't have any antenna that need much that headroom. > >> > >> That's 8Vpp open circuit, 4Vpp loaded. > > > > Well then, eazy peazy. I used a circuit that used positive feedback to > > make the output impedance look higher than the resistor in the circuit. > > I think I used 12.5 or maybe it was just 12 and got multiplied by 4. > > This makes the calculation of the gain a little more complex so you > > would not be able to adjust the gain with a pot or anything... unless it > > was on an earlier stage. > > > > The middle stage with the single transistor, anything special about > > that? It has a connection with caps I'm not familiar with from the > > emitter to the input. That would be a low level of positive feedback I > > believe. Any idea why? He's bootstrapping the input impedance to avoid loading the FET stage. Kleijer's crafty. > Hey I'm a semi-retired shrimp seller with a little bit of technical > skill. I did a good job of replicating the circuit, I didn't design it. > I can only explain operation on a simple level. If I had more knowledge > I would have corrected the distortion at increased input levels. > I suspect a good analog engineer would have done a lot of things > different to reach the goal of high input impedance, 50 ohm output. On > the other hand Kleijer built a working circuit and later went back and > built an improved second version. I follow the crystal radio community > and have not heard of anyone else that built the circuit, it's a shame > because it is a very useful piece of equipment for experimenting with > high Q LC circuits. ISTM Kleijer did a very decent job, and got something more than good enough for his task. And was nice enough to share it with everyone. +1 for Kleijer. > I hope to take dagmar's design and improve it further. We could do that, but it would add complexity without much benefit to your application. Using an op-amp buffer instead of a BJT follower is one possibility... > >>> I designed an opamp circuit to output an 8 volt signal with a 12 volt > >>> supply into 50 ohm cable. I didn't quite get 8 volts before it starts > >>> to distort, but it was close. I believe the gain-bandwidth product of > >>> the amp was over 30 MHz, so it should do ok at 10 MHz and no gain. But > >>> then you need a little gain I guess. Opps, no, the GB was 15 MHz. > > > > Wait a minute!!! That bootstrap of the input resistors won't work. The > > 470 ohm source resistor is there to set a bias point with the source > > higher than the gate. The resistors are there to set the DC voltage of > > the gate to ground. Perhaps a cap could be used to feed the point > > between the two resistors? There's nothing stopping us from running the JFET at Vgs=0. That just runs it richer. > > I just realized that is the purpose of the two caps on T2 emitter to the > > 47 ohm resistor. It allows the resistors to set the DC operating point > > but bootstraps their capacitance. No? > > > ?? > I have looked for a data sheet on the BF256C, all I can find is very > limited info, Anyone find a data sheet with the device capacitances? > Mikek In the old days, all the various JFETs were selections taken from one of several different processes. Fairchild's BF256B datasheet says it's made on Process 50, so it should have pretty much the same capacitances as any other JFET from the same process, e.g., https://www.fairchildsemi.com/datasheets/MM/MMBF5484.pdf Cheers, James Arthur
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| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-21 11:54 -0500 |
| Message-ID | <oarllr$qh6$1@dont-email.me> |
| In reply to | #452889 |
On 3/21/2017 9:57 AM, dagmargoodboat@yahoo.com wrote:
> On Tuesday, March 21, 2017 at 8:54:35 AM UTC-4, amdx wrote:
>> On 3/20/2017 10:25 PM, rickman wrote:
>>> On 3/20/2017 10:23 PM, amdx wrote:
>>>> On 3/20/2017 8:28 PM, rickman wrote:
>>>>> On 3/20/2017 9:09 PM, amdx wrote:
>
>>>>>> I'm sure it could be built with a couple of opamps. It is a 50 ohm
>>>>>> output. Could probably do better, this starts to distort at I think
>>>>>> 8 Vpp. But I don't have any antenna that need much that headroom.
>>>>
>>>> That's 8Vpp open circuit, 4Vpp loaded.
>>>
>>> Well then, eazy peazy. I used a circuit that used positive feedback to
>>> make the output impedance look higher than the resistor in the circuit.
>>> I think I used 12.5 or maybe it was just 12 and got multiplied by 4.
>>> This makes the calculation of the gain a little more complex so you
>>> would not be able to adjust the gain with a pot or anything... unless it
>>> was on an earlier stage.
>>>
>>> The middle stage with the single transistor, anything special about
>>> that? It has a connection with caps I'm not familiar with from the
>>> emitter to the input. That would be a low level of positive feedback I
>>> believe. Any idea why?
>
> He's bootstrapping the input impedance to avoid loading the FET stage.
> Kleijer's crafty.
>
>> Hey I'm a semi-retired shrimp seller with a little bit of technical
>> skill. I did a good job of replicating the circuit, I didn't design it.
>> I can only explain operation on a simple level. If I had more knowledge
>> I would have corrected the distortion at increased input levels.
>> I suspect a good analog engineer would have done a lot of things
>> different to reach the goal of high input impedance, 50 ohm output. On
>> the other hand Kleijer built a working circuit and later went back and
>> built an improved second version. I follow the crystal radio community
>> and have not heard of anyone else that built the circuit, it's a shame
>> because it is a very useful piece of equipment for experimenting with
>> high Q LC circuits.
>
> ISTM Kleijer did a very decent job, and got something more than good
> enough for his task. And was nice enough to share it with everyone.
> +1 for Kleijer.
>
>> I hope to take dagmar's design and improve it further.
>
> We could do that, but it would add complexity without much benefit to
> your application. Using an op-amp buffer instead of a BJT follower is
> one possibility...
I worded that poorly, I meant, take dagmar's design to further improve
Kleijers design. :-)
I hack, I don't design.
Mikek
>
> Cheers,
> James Arthur
>
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| From | dagmargoodboat@yahoo.com |
|---|---|
| Date | 2017-03-21 12:21 -0700 |
| Message-ID | <1e7d0dfd-4da7-449e-9a49-45c81a4daa3c@googlegroups.com> |
| In reply to | #452899 |
On Tuesday, March 21, 2017 at 12:54:05 PM UTC-4, amdx wrote: > On 3/21/2017 9:57 AM, dagmargoodboat@yahoo.com wrote: > > On Tuesday, March 21, 2017 at 8:54:35 AM UTC-4, amdx wrote: > >> On 3/20/2017 10:25 PM, rickman wrote: > >>> On 3/20/2017 10:23 PM, amdx wrote: > >>>> On 3/20/2017 8:28 PM, rickman wrote: > >>>>> On 3/20/2017 9:09 PM, amdx wrote: > > > >>>>>> I'm sure it could be built with a couple of opamps. It is a 50 ohm > >>>>>> output. Could probably do better, this starts to distort at I think > >>>>>> 8 Vpp. But I don't have any antenna that need much that headroom. > >>>> > >>>> That's 8Vpp open circuit, 4Vpp loaded. > >>> > >>> Well then, eazy peazy. I used a circuit that used positive feedback to > >>> make the output impedance look higher than the resistor in the circuit. > >>> I think I used 12.5 or maybe it was just 12 and got multiplied by 4. > >>> This makes the calculation of the gain a little more complex so you > >>> would not be able to adjust the gain with a pot or anything... unless it > >>> was on an earlier stage. > >>> > >>> The middle stage with the single transistor, anything special about > >>> that? It has a connection with caps I'm not familiar with from the > >>> emitter to the input. That would be a low level of positive feedback I > >>> believe. Any idea why? > > > > He's bootstrapping the input impedance to avoid loading the FET stage. > > Kleijer's crafty. > > > >> Hey I'm a semi-retired shrimp seller with a little bit of technical > >> skill. I did a good job of replicating the circuit, I didn't design it. > >> I can only explain operation on a simple level. If I had more knowledge > >> I would have corrected the distortion at increased input levels. > >> I suspect a good analog engineer would have done a lot of things > >> different to reach the goal of high input impedance, 50 ohm output. On > >> the other hand Kleijer built a working circuit and later went back and > >> built an improved second version. I follow the crystal radio community > >> and have not heard of anyone else that built the circuit, it's a shame > >> because it is a very useful piece of equipment for experimenting with > >> high Q LC circuits. > > > > ISTM Kleijer did a very decent job, and got something more than good > > enough for his task. And was nice enough to share it with everyone. > > +1 for Kleijer. > > > >> I hope to take dagmar's design and improve it further. > > > > We could do that, but it would add complexity without much benefit to > > your application. Using an op-amp buffer instead of a BJT follower is > > one possibility... > > I worded that poorly, I meant, take dagmar's design to further improve > Kleijers design. :-) > I hack, I don't design. > Mikek Oh I'm not offended, trust me. I was agreeing with you that my circuit's performance could be improved on. I'm well aware, we just don't need it. Give me one more transistor and it could be markedly better still, but we don't need it. It's a waste to overcomplicate a thing. I was also giving thumbs-up to Kleijer. A schematic is a window into the designer's soul. Kleijer has soul. Cheers, James Arthur
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| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-21 21:40 -0500 |
| Message-ID | <oaso22$d3a$1@dont-email.me> |
| In reply to | #452927 |
On 3/21/2017 2:21 PM, dagmargoodboat@yahoo.com wrote:
> On Tuesday, March 21, 2017 at 12:54:05 PM UTC-4, amdx wrote:
>> On 3/21/2017 9:57 AM, dagmargoodboat@yahoo.com wrote:
>>> On Tuesday, March 21, 2017 at 8:54:35 AM UTC-4, amdx wrote:
>>>> On 3/20/2017 10:25 PM, rickman wrote:
>>>>> On 3/20/2017 10:23 PM, amdx wrote:
>>>>>> On 3/20/2017 8:28 PM, rickman wrote:
>>>>>>> On 3/20/2017 9:09 PM, amdx wrote:
>>>
>>>>>>>> I'm sure it could be built with a couple of opamps. It is a 50 ohm
>>>>>>>> output. Could probably do better, this starts to distort at I think
>>>>>>>> 8 Vpp. But I don't have any antenna that need much that headroom.
>>>>>>
>>>>>> That's 8Vpp open circuit, 4Vpp loaded.
>>>>>
>>>>> Well then, eazy peazy. I used a circuit that used positive feedback to
>>>>> make the output impedance look higher than the resistor in the circuit.
>>>>> I think I used 12.5 or maybe it was just 12 and got multiplied by 4.
>>>>> This makes the calculation of the gain a little more complex so you
>>>>> would not be able to adjust the gain with a pot or anything... unless it
>>>>> was on an earlier stage.
>>>>>
>>>>> The middle stage with the single transistor, anything special about
>>>>> that? It has a connection with caps I'm not familiar with from the
>>>>> emitter to the input. That would be a low level of positive feedback I
>>>>> believe. Any idea why?
>>>
>>> He's bootstrapping the input impedance to avoid loading the FET stage.
>>> Kleijer's crafty.
>>>
>>>> Hey I'm a semi-retired shrimp seller with a little bit of technical
>>>> skill. I did a good job of replicating the circuit, I didn't design it.
>>>> I can only explain operation on a simple level. If I had more knowledge
>>>> I would have corrected the distortion at increased input levels.
>>>> I suspect a good analog engineer would have done a lot of things
>>>> different to reach the goal of high input impedance, 50 ohm output. On
>>>> the other hand Kleijer built a working circuit and later went back and
>>>> built an improved second version. I follow the crystal radio community
>>>> and have not heard of anyone else that built the circuit, it's a shame
>>>> because it is a very useful piece of equipment for experimenting with
>>>> high Q LC circuits.
>>>
>>> ISTM Kleijer did a very decent job, and got something more than good
>>> enough for his task. And was nice enough to share it with everyone.
>>> +1 for Kleijer.
>>>
>>>> I hope to take dagmar's design and improve it further.
>>>
>>> We could do that, but it would add complexity without much benefit to
>>> your application. Using an op-amp buffer instead of a BJT follower is
>>> one possibility...
>>
>> I worded that poorly, I meant, take dagmar's design to further improve
>> Kleijers design. :-)
>> I hack, I don't design.
>> Mikek
>
> Oh I'm not offended, trust me.
I wasn't thinking I offended you, I just didn't want to leave the
impression that I could improve your circuit. :-)
> I was agreeing with you that my circuit's
> performance could be improved on. I'm well aware, we just don't need it.
> Give me one more transistor and it could be markedly better still, but
> we don't need it. It's a waste to overcomplicate a thing.
>
> I was also giving thumbs-up to Kleijer. A schematic is a window into the
> designer's soul. Kleijer has soul.
I spent hours reading all the different experiments that he did. Great
stuff. I posted his very low voltage osc. a few times, says he stopped
working on it when it would started and oscillated at 5.5mV. (.0055V)
> http://www.dicks-website.eu/fetosc/enindex.htm
Mikek
>
> Cheers,
> James Arthur
>
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-21 13:27 -0400 |
| Message-ID | <oarnk0$247$1@dont-email.me> |
| In reply to | #452879 |
On 3/21/2017 8:54 AM, amdx wrote: > On 3/20/2017 10:25 PM, rickman wrote: >> On 3/20/2017 10:23 PM, amdx wrote: >>> On 3/20/2017 8:28 PM, rickman wrote: >>>> On 3/20/2017 9:09 PM, amdx wrote: >>>>> On 3/20/2017 7:55 PM, rickman wrote: >>>>>> On 3/20/2017 6:54 PM, amdx wrote: >>>>>>> On 3/20/2017 5:27 PM, rickman wrote: >>>>>>>> On 3/20/2017 6:21 PM, amdx wrote: >>>>>>>>> On 3/20/2017 3:34 PM, rickman wrote: >>>>>>>>>> On 3/20/2017 2:16 PM, amdx wrote: >>>>>>>>>>> On 3/20/2017 11:29 AM, dagmargoodboat@yahoo.com wrote: >>>>>>>>>>> >>>>>>>>>>> If you will look at my picture, >>>>>>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>> you will notice I put the 470 ohm (turquoise resistor) on the >>>>>>>>>>> other >>>>>>>>>>> side >>>>>>>>>>> of the shield, (I don't know why). >>>>>>>>>>> What affect would that have? >>>>>>>>>>> >>>>>>>>>>>> On Monday, March 20, 2017 at 9:36:51 AM UTC-4, amdx wrote: >>>>>>>>>>>>> If you want to get fancier >>>>>>>>>>>>> and even lower input capacitance we can bootstrap the drain, >>>>>>>>>>>>> too. A >>>>>>>>>>>>> bootstrapped shield for your pass-through (where you bring the >>>>>>>>>>>>> input >>>>>>>>>>>>> through your metal box) would help, too. >>>>>>>>>>> >>>>>>>>>>> OK, I'd like to get fancy, but I don't understand "A >>>>>>>>>>> bootstrapped >>>>>>>>>>> shield" for my pass through. >>>>>>>>>>> I would like to understand physically what I need to do. >>>>>>>>>> >>>>>>>>>> I have seen this done for electrometers where the concern is >>>>>>>>>> leakage >>>>>>>>>> current. There they call it a "guard" ring. As James says, it >>>>>>>>>> will >>>>>>>>>> also reduce input capacitance. >>>>>>>>>> >>>>>>>>>> I don't understand how you can bootstrap the drain though. Since >>>>>>>>>> it is >>>>>>>>>> connected to the positive rail, I'm not even sure what that >>>>>>>>>> means. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>>> Here's another picture showing the input, there is 5/8" hole in >>>>>>>>>>> the >>>>>>>>>>> case >>>>>>>>>>> and I glued polystyrene sheet over it with the input wire coming >>>>>>>>>>> out >>>>>>>>>>> the >>>>>>>>>>> center. >>>>>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/Input.jpg >>>>>>>>>>> Ah, here's a picture of a previous input cap, I don't use >>>>>>>>>>> anymore, >>>>>>>>>>> but >>>>>>>>>>> it shows the input better. >>>>>>>>>>>> http://i395.photobucket.com/albums/pp37/Qmavam/1cmx1cmspaced5mm.jpg >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> This latter image doesn't look like what is used in this image. >>>>>>>>>> >>>>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html >>>>>>>>>> >>>>>>>>>> Was this just a temporary cap in place until you got the detail >>>>>>>>>> work >>>>>>>>>> done? >>>>>>>>>> >>>>>>>>> >>>>>>>>> Yes, that was a first iteration, nothing wrong with it, but it >>>>>>>>> wasn't >>>>>>>>> as stable (two wires with a weights on the end) as my tiny >>>>>>>>> piece of >>>>>>>>> double sided pcb. >>>>>>>> >>>>>>>> Oh, so the free hanging copper is the old cap and the thing I can't >>>>>>>> see >>>>>>>> is the PCB cap which you like better? >>>>>>>> >>>>>>> >>>>>>> When you say can't see, do you mean it small and your looking >>>>>>> side on >>>>>>> or do you mean you didn't see a link? >>>>>>>> http://s395.photobucket.com/user/Qmavam/media/inside.jpg.html?o=163 >>>>>>> >>>>>>> btw the 0.3pf cap is a approximately 1/8" disc of Teflon pcb 0.32" >>>>>>> thick. PCB material is not critical. Easy enough to set size, check >>>>>>> the >>>>>>> gain of your amp without the input cap, then reduce the size of your >>>>>>> input cap until gain equals 1. >>>>>> >>>>>> I just meant it is small and I couldn't see what it was. Initially I >>>>>> thought it might be a small value ceramic cap you put in place to >>>>>> check >>>>>> out the amp before you optimized the cap. Now I realize it is a very >>>>>> small piece of PCB and *is* the optimized cap. I also didn't know >>>>>> which >>>>>> image was earlier and which was later. >>>>>> >>>>>> Why would you adjust the overall circuit gain by trimming the cap? >>>>>> The >>>>>> amp gain can be trimmed, no? >>>>>> >>>>> I'm sure the amp can be changed, but the end game was to make the >>>>> input >>>>> cap small, I couldn't go much smaller. >>>>> >>>>>> What frequency range is this amp intended to be used for? Nearly all >>>>>> the stuff I've seen where Q matters is LF or MF. >>>>> >>>>> Kleijer says it's flat from 10kHz to 10 MHz. >>>>> >>>>>> They use loop antennas >>>>>> for higher frequencies, but with too high Q the bandwidth gets so >>>>>> narrow >>>>>> even voice won't get through, just CW. >>>>>> >>>>> Most of the stuff I'm looking at is crystal radio, by the time you >>>>> start driving a headphone your Q gets lowered a lot. I never hear the >>>>> crystal radio guys complain about lack of bandwidth. >>>>> >>>>>> Some of the antennas Kleijer uses I would think would limit the >>>>>> bandwidth of his circuits with Q of over 1000. >>>>>> >>>>> Again not a common problem, but easy to fix with a load resistor. >>>> >>>> If the headphones or load resistor limit the Q, what is the bleeping >>>> point of all that Litz wire and custom tuning capacitor stuff? I >>>> thought the whole point was to get the Q as high as possible. >>> >>> Yes, it is. But you still need to get the maximum power out to drive >>> your headphones. >>> In a perfect system, you would drop your Q by half to get maximum >>> audio. But the diode gets involved and that I can't decipher. >>> >>> >>>> If you start with a Q over 1000 and end up with a few hundred, I >>>> wouldn't >>>> expect that to be distinguishable from a coil with a Q of some hundreds >>>> which is where Kleijer started in his coil investigations. >>> >>> This is radio dxing, grab every db of signal! >>>> >>>> >>>>>> If the frequencies are not so high, why not use an opamp for the >>>>>> final >>>>>> stage rather than the much more complex push-pull stage? I assume >>>>>> that >>>>>> is intended to be in essence a "power" output stage and does not >>>>>> otherwise contribute significantly to the characteristics of the >>>>>> rest of >>>>>> the circuit. >>>>>> >>>>> I'm sure it could be built with a couple of opamps. It is a 50 ohm >>>>> output. Could probably do better, this starts to distort at I think >>>>> 8 Vpp. But I don't have any antenna that need much that headroom. >>> >>> That's 8Vpp open circuit, 4Vpp loaded. >> >> Well then, eazy peazy. I used a circuit that used positive feedback to >> make the output impedance look higher than the resistor in the circuit. >> I think I used 12.5 or maybe it was just 12 and got multiplied by 4. >> This makes the calculation of the gain a little more complex so you >> would not be able to adjust the gain with a pot or anything... unless it >> was on an earlier stage. >> >> The middle stage with the single transistor, anything special about >> that? It has a connection with caps I'm not familiar with from the >> emitter to the input. That would be a low level of positive feedback I >> believe. Any idea why? >> > Hey I'm a semi-retired shrimp seller with a little bit of technical > skill. I did a good job of replicating the circuit, I didn't design it. > I can only explain operation on a simple level. If I had more knowledge > I would have corrected the distortion at increased input levels. > I suspect a good analog engineer would have done a lot of things > different to reach the goal of high input impedance, 50 ohm output. On > the other hand Kleijer built a working circuit and later went back and > built an improved second version. I follow the crystal radio community > and have not heard of anyone else that built the circuit, it's a shame > because it is a very useful piece of equipment for experimenting with > high Q LC circuits. > I hope to take dagmar's design and improve it further. > > >>>> I designed an opamp circuit to output an 8 volt signal with a 12 volt >>>> supply into 50 ohm cable. I didn't quite get 8 volts before it starts >>>> to distort, but it was close. I believe the gain-bandwidth product of >>>> the amp was over 30 MHz, so it should do ok at 10 MHz and no gain. But >>>> then you need a little gain I guess. Opps, no, the GB was 15 MHz. >> >> Wait a minute!!! That bootstrap of the input resistors won't work. The >> 470 ohm source resistor is there to set a bias point with the source >> higher than the gate. The resistors are there to set the DC voltage of >> the gate to ground. Perhaps a cap could be used to feed the point >> between the two resistors? >> >> I just realized that is the purpose of the two caps on T2 emitter to the >> 47 ohm resistor. It allows the resistors to set the DC operating point >> but bootstraps their capacitance. No? >> > ?? > I have looked for a data sheet on the BF256C, all I can find is very > limited info, Anyone find a data sheet with the device capacitances? NXP says the BF245C is the same as (or a replacement for) the BF256C. Here is a data sheet, pretty complete. http://www.nxp.com/documents/data_sheet/BF245A-B-C.pdf -- Rick C
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| From | "billbowden" <bperryb@bowdenshobbycircuits.info> |
|---|---|
| Date | 2017-03-20 15:41 -0800 |
| Message-ID | <58d068a7$0$59750$c3e8da3$460562f1@news.astraweb.com> |
| In reply to | #452637 |
"rickman" <gnuarm@gmail.com> wrote in message news:oan4s4$99i$1@dont-email.me... > On 3/19/2017 7:31 PM, billbowden wrote: >> "amdx" <nojunk@knology.net> wrote in message >> news:oam0ee$ch5$1@dont-email.me... >>> On 3/14/2017 11:18 PM, billbowden wrote: >>>> Which is a better design. Suppose you have a 6 inch length of PVC pipe >>>> with >>>> numerous turns of wire that has an inductance of say 200uH. Now suppose >>>> you >>>> use the same (6 inch) piece of PVC with a ferrite rod in the core with >>>> considerably fewer turns of wire. Which one would capture the most >>>> signal >>>> at the AM Broadcast frequencies (500K to 2 Megs) and produce the >>>> greatest >>>> signal output? Would it be more ferrite, or more wire? >>>> >>> >>> I'll run the experiment. >>> >>> Do you want it tuned? >>> >>> If not, I have no way to measure the signals of my local stations. >>> I need the resonance peaking to see the signal. >>> >>> What diameter PVC? >>> >>> I have 1/2" OD polystyrene that will allow a little closer coupling >>> between the ferrite and the wire. 400 turns #28 = 203uh air core. >>> >>> I have 1/2" CPVC. actual OD. 0.615" >>> 290 turns #28 = 200uh air core >>> >>> >>> I have 1/2 PVC, actual OD. 0.832. 175 turns #28 = 205uh air core. >>> >>> Pick one. >>> >>> I'll also wind one with less turns and use my best Q rod that is 8" long >>> x >>> 0.375" diameter. >>> >>> I will check three frequencies, 590Khz, 1290kHz and 1430Khz. >>> >>> I made a post last night of the wrong experiment (6"dia not 6" long) >>> It has not shown up this morning, so I'll repeat my measurement method. >>> >>> To measure the signal I have a very high input impedance amp with a >>> gain >>> of 1. >>> I use the amp to drive a scope (ch 2) set at 50mV/div. I took the >>> channel >>> 2 output from the back of the scope to drive a Boonton 92BD RF millivolt >>> meter. I use the scope to compare the visual to audio from a portable >>> radio to know where I am tuned. >>> Modulation causes a bit of amplitude bounce, but I do a visual average. >>> >>> Let me know what you want. >>> Mikek >>> >> >> Actually, I'm just interested in comparing the response of two identical >> loopsticks, one using an air core and the other using a ferrite core. I >> could do the experiment since there is a 50KW station about 7 miles away >> and >> I can see the signal from the antenna loop directly on a scope. I can get >> about 1 volt peak using a loop antenna of about 15 inches square. I just >> thought someone would know the answer without a lot of experimenting. I >> have >> a portable car radio with a air core loop antenna mounted on the chassis >> that measures 6.5 inch by 3/4 diameter and about 300 turns of small wire. >> Works fine and gets stations 130 miles away. But it's a power hog and >> draws >> 100mA from a 12 volt battery. I suppose a good test would be to use a >> shorter ferrite rod and fewer turns to compare the results. But I'm lazy >> and >> just want to know which idea is better. > > Connecting a scope directly to a loop antenna may cause a loss of Q. I'm > hoping not, as I am building a very high Q antenna that will depend on a > high impedance not sapping it, but it depends on the antenna. The point > is if your measurement saps the Q, then any impact on the Q by the ferrite > will not be noticed. > I just looked at my 15 inch square (air core) loop antenna on a scope. The amplitude was about 1 volt P-P. I connected a 150K resistor across the loop and the amplitude dropped to about half that. So, the impedance looks to be about 150K. The scope input is 1 Meg and 30pF and I used a 10X probe. The Q of the antenna was measured at 300 at the low end of the band (600Khz) and 200 at the high end. That was using a Boonton Q meter. So, it doesn't look like connecting a scope has much effect on Q in this case. But possibly doing the same test on a short ferrite loop would give different results. Actually, the Q of the loop should be about 100 or less if you want a 10Khz bandwidth.
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| From | amdx <nojunk@knology.net> |
|---|---|
| Date | 2017-03-20 19:13 -0500 |
| Message-ID | <oapr2v$kvr$1@dont-email.me> |
| In reply to | #452803 |
On 3/20/2017 6:41 PM, billbowden wrote:
> "rickman" <gnuarm@gmail.com> wrote in message
> news:oan4s4$99i$1@dont-email.me...
>> On 3/19/2017 7:31 PM, billbowden wrote:
>>> "amdx" <nojunk@knology.net> wrote in message
>>> news:oam0ee$ch5$1@dont-email.me...
>>>> On 3/14/2017 11:18 PM, billbowden wrote:
>>>>> Which is a better design. Suppose you have a 6 inch length of PVC pipe
>>>>> with
>>>>> numerous turns of wire that has an inductance of say 200uH. Now suppose
>>>>> you
>>>>> use the same (6 inch) piece of PVC with a ferrite rod in the core with
>>>>> considerably fewer turns of wire. Which one would capture the most
>>>>> signal
>>>>> at the AM Broadcast frequencies (500K to 2 Megs) and produce the
>>>>> greatest
>>>>> signal output? Would it be more ferrite, or more wire?
>>>>>
>>>>
>>>> I'll run the experiment.
>>>>
>>>> Do you want it tuned?
>>>>
>>>> If not, I have no way to measure the signals of my local stations.
>>>> I need the resonance peaking to see the signal.
>>>>
>>>> What diameter PVC?
>>>>
>>>> I have 1/2" OD polystyrene that will allow a little closer coupling
>>>> between the ferrite and the wire. 400 turns #28 = 203uh air core.
>>>>
>>>> I have 1/2" CPVC. actual OD. 0.615"
>>>> 290 turns #28 = 200uh air core
>>>>
>>>>
>>>> I have 1/2 PVC, actual OD. 0.832. 175 turns #28 = 205uh air core.
>>>>
>>>> Pick one.
>>>>
>>>> I'll also wind one with less turns and use my best Q rod that is 8" long
>>>> x
>>>> 0.375" diameter.
>>>>
>>>> I will check three frequencies, 590Khz, 1290kHz and 1430Khz.
>>>>
>>>> I made a post last night of the wrong experiment (6"dia not 6" long)
>>>> It has not shown up this morning, so I'll repeat my measurement method.
>>>>
>>>> To measure the signal I have a very high input impedance amp with a
>>>> gain
>>>> of 1.
>>>> I use the amp to drive a scope (ch 2) set at 50mV/div. I took the
>>>> channel
>>>> 2 output from the back of the scope to drive a Boonton 92BD RF millivolt
>>>> meter. I use the scope to compare the visual to audio from a portable
>>>> radio to know where I am tuned.
>>>> Modulation causes a bit of amplitude bounce, but I do a visual average.
>>>>
>>>> Let me know what you want.
>>>> Mikek
>>>>
>>>
>>> Actually, I'm just interested in comparing the response of two identical
>>> loopsticks, one using an air core and the other using a ferrite core. I
>>> could do the experiment since there is a 50KW station about 7 miles away
>>> and
>>> I can see the signal from the antenna loop directly on a scope. I can get
>>> about 1 volt peak using a loop antenna of about 15 inches square. I just
>>> thought someone would know the answer without a lot of experimenting. I
>>> have
>>> a portable car radio with a air core loop antenna mounted on the chassis
>>> that measures 6.5 inch by 3/4 diameter and about 300 turns of small wire.
>>> Works fine and gets stations 130 miles away. But it's a power hog and
>>> draws
>>> 100mA from a 12 volt battery. I suppose a good test would be to use a
>>> shorter ferrite rod and fewer turns to compare the results. But I'm lazy
>>> and
>>> just want to know which idea is better.
>>
>> Connecting a scope directly to a loop antenna may cause a loss of Q. I'm
>> hoping not, as I am building a very high Q antenna that will depend on a
>> high impedance not sapping it, but it depends on the antenna. The point
>> is if your measurement saps the Q, then any impact on the Q by the ferrite
>> will not be noticed.
>>
>
> I just looked at my 15 inch square (air core) loop antenna on a scope. The
> amplitude was about 1 volt P-P. I connected a 150K resistor across the loop
> and the amplitude dropped to about half that. So, the impedance looks to be
> about 150K. The scope input is 1 Meg and 30pF and I used a 10X probe. The Q
> of the antenna was measured at 300 at the low end of the band (600Khz) and
> 200 at the high end. That was using a Boonton Q meter. So, it doesn't look
> like connecting a scope has much effect on Q in this case. But possibly
> doing the same test on a short ferrite loop would give different results.
> Actually, the Q of the loop should be about 100 or less if you want a 10Khz
> bandwidth.
>
Sounds about right, the coil I measured has a Q of 1000 to 1400 at
800kHz. If we say it is Q = 1200 and the Reactance at 800kHz is 1,166
ohms, the resonant peak will be 1.33Megohms.
btw, I also measured my Qs with a Boonton 260. I had to reduce the
injection voltage (Multiplier) way down in order to make that high Q
measurement,
Mikek
---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-20 21:18 -0400 |
| Message-ID | <oapur9$tvj$1@dont-email.me> |
| In reply to | #452803 |
On 3/20/2017 7:41 PM, billbowden wrote: > "rickman" <gnuarm@gmail.com> wrote in message > news:oan4s4$99i$1@dont-email.me... >> On 3/19/2017 7:31 PM, billbowden wrote: >>> "amdx" <nojunk@knology.net> wrote in message >>> news:oam0ee$ch5$1@dont-email.me... >>>> On 3/14/2017 11:18 PM, billbowden wrote: >>>>> Which is a better design. Suppose you have a 6 inch length of PVC pipe >>>>> with >>>>> numerous turns of wire that has an inductance of say 200uH. Now suppose >>>>> you >>>>> use the same (6 inch) piece of PVC with a ferrite rod in the core with >>>>> considerably fewer turns of wire. Which one would capture the most >>>>> signal >>>>> at the AM Broadcast frequencies (500K to 2 Megs) and produce the >>>>> greatest >>>>> signal output? Would it be more ferrite, or more wire? >>>>> >>>> >>>> I'll run the experiment. >>>> >>>> Do you want it tuned? >>>> >>>> If not, I have no way to measure the signals of my local stations. >>>> I need the resonance peaking to see the signal. >>>> >>>> What diameter PVC? >>>> >>>> I have 1/2" OD polystyrene that will allow a little closer coupling >>>> between the ferrite and the wire. 400 turns #28 = 203uh air core. >>>> >>>> I have 1/2" CPVC. actual OD. 0.615" >>>> 290 turns #28 = 200uh air core >>>> >>>> >>>> I have 1/2 PVC, actual OD. 0.832. 175 turns #28 = 205uh air core. >>>> >>>> Pick one. >>>> >>>> I'll also wind one with less turns and use my best Q rod that is 8" long >>>> x >>>> 0.375" diameter. >>>> >>>> I will check three frequencies, 590Khz, 1290kHz and 1430Khz. >>>> >>>> I made a post last night of the wrong experiment (6"dia not 6" long) >>>> It has not shown up this morning, so I'll repeat my measurement method. >>>> >>>> To measure the signal I have a very high input impedance amp with a >>>> gain >>>> of 1. >>>> I use the amp to drive a scope (ch 2) set at 50mV/div. I took the >>>> channel >>>> 2 output from the back of the scope to drive a Boonton 92BD RF millivolt >>>> meter. I use the scope to compare the visual to audio from a portable >>>> radio to know where I am tuned. >>>> Modulation causes a bit of amplitude bounce, but I do a visual average. >>>> >>>> Let me know what you want. >>>> Mikek >>>> >>> >>> Actually, I'm just interested in comparing the response of two identical >>> loopsticks, one using an air core and the other using a ferrite core. I >>> could do the experiment since there is a 50KW station about 7 miles away >>> and >>> I can see the signal from the antenna loop directly on a scope. I can get >>> about 1 volt peak using a loop antenna of about 15 inches square. I just >>> thought someone would know the answer without a lot of experimenting. I >>> have >>> a portable car radio with a air core loop antenna mounted on the chassis >>> that measures 6.5 inch by 3/4 diameter and about 300 turns of small wire. >>> Works fine and gets stations 130 miles away. But it's a power hog and >>> draws >>> 100mA from a 12 volt battery. I suppose a good test would be to use a >>> shorter ferrite rod and fewer turns to compare the results. But I'm lazy >>> and >>> just want to know which idea is better. >> >> Connecting a scope directly to a loop antenna may cause a loss of Q. I'm >> hoping not, as I am building a very high Q antenna that will depend on a >> high impedance not sapping it, but it depends on the antenna. The point >> is if your measurement saps the Q, then any impact on the Q by the ferrite >> will not be noticed. >> > > I just looked at my 15 inch square (air core) loop antenna on a scope. The > amplitude was about 1 volt P-P. I connected a 150K resistor across the loop > and the amplitude dropped to about half that. So, the impedance looks to be > about 150K. The scope input is 1 Meg and 30pF and I used a 10X probe. The Q > of the antenna was measured at 300 at the low end of the band (600Khz) and > 200 at the high end. That was using a Boonton Q meter. So, it doesn't look > like connecting a scope has much effect on Q in this case. But possibly > doing the same test on a short ferrite loop would give different results. > Actually, the Q of the loop should be about 100 or less if you want a 10Khz > bandwidth. I'm not looking for bandwidth. I don't think I can get the Q high enough to cause a bandwidth problem. -- Rick C
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| From | "Tim Williams" <tiwill@seventransistorlabs.com> |
|---|---|
| Date | 2017-03-21 04:35 -0500 |
| Message-ID | <oaqrva$sr1$1@dont-email.me> |
| In reply to | #452803 |
"billbowden" <bperryb@bowdenshobbycircuits.info> wrote in message news:58d068a7$0$59750$c3e8da3$460562f1@news.astraweb.com... > I just looked at my 15 inch square (air core) loop antenna on a scope. The > amplitude was about 1 volt P-P. I connected a 150K resistor across the > loop and the amplitude dropped to about half that. So, the impedance looks > to be about 150K. The scope input is 1 Meg and 30pF and I used a 10X > probe. Mind that the probe acts like (9M || 11pF) + (100pF || 1M), but the cable and scope input aren't actually 100pF but are lossy, having probably around 50 ohms ESR, and all the distributed L and C implied by a transmission line. If you look at (10pF + 50) ohms, the parallel equivalent is 5M (at 1MHz, to ballpark it), so the overall resistance is about 3M. Still pretty big, but only 20 times bigger than 150k, not a huge amount. :) Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
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| From | Tauno Voipio <tauno.voipio@notused.fi.invalid> |
|---|---|
| Date | 2017-03-20 11:06 +0200 |
| Message-ID | <oao5t3$ds8$2@dont-email.me> |
| In reply to | #452564 |
On 19.3.17 15:20, amdx wrote: > On 3/14/2017 11:18 PM, billbowden wrote: >> Which is a better design. Suppose you have a 6 inch length of PVC pipe >> with >> numerous turns of wire that has an inductance of say 200uH. Now >> suppose you >> use the same (6 inch) piece of PVC with a ferrite rod in the core with >> considerably fewer turns of wire. Which one would capture the most >> signal >> at the AM Broadcast frequencies (500K to 2 Megs) and produce the greatest >> signal output? Would it be more ferrite, or more wire? >> > > I'll run the experiment. > > Do you want it tuned? > > If not, I have no way to measure the signals of my local stations. > I need the resonance peaking to see the signal. > > What diameter PVC? > > I have 1/2" OD polystyrene that will allow a little closer coupling > between the ferrite and the wire. 400 turns #28 = 203uh air core. > > I have 1/2" CPVC. actual OD. 0.615" > 290 turns #28 = 200uh air core > > > I have 1/2 PVC, actual OD. 0.832. 175 turns #28 = 205uh air core. > > Pick one. > > I'll also wind one with less turns and use my best Q rod that is 8" long > x 0.375" diameter. > > I will check three frequencies, 590Khz, 1290kHz and 1430Khz. > > I made a post last night of the wrong experiment (6"dia not 6" long) > It has not shown up this morning, so I'll repeat my measurement method. > > To measure the signal I have a very high input impedance amp with a > gain of 1. > I use the amp to drive a scope (ch 2) set at 50mV/div. I took the > channel 2 output from the back of the scope to drive a Boonton 92BD RF > millivolt meter. I use the scope to compare the visual to audio from a > portable radio to know where I am tuned. > Modulation causes a bit of amplitude bounce, but I do a visual average. > > Let me know what you want. > Mikek > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > Please do not use PVC as RF insulation or support pieces. It is lossy to extremely lossy at RF. -- -TV
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| From | Joerg <news@analogconsultants.com> |
|---|---|
| Date | 2017-03-24 10:14 -0700 |
| Message-ID | <ejl2g6Foq69U1@mid.individual.net> |
| In reply to | #452698 |
On 2017-03-20 02:06, Tauno Voipio wrote: > On 19.3.17 15:20, amdx wrote: >> On 3/14/2017 11:18 PM, billbowden wrote: >>> Which is a better design. Suppose you have a 6 inch length of PVC pipe >>> with >>> numerous turns of wire that has an inductance of say 200uH. Now >>> suppose you >>> use the same (6 inch) piece of PVC with a ferrite rod in the core with >>> considerably fewer turns of wire. Which one would capture the most >>> signal >>> at the AM Broadcast frequencies (500K to 2 Megs) and produce the >>> greatest >>> signal output? Would it be more ferrite, or more wire? >>> >> >> I'll run the experiment. >> >> Do you want it tuned? >> >> If not, I have no way to measure the signals of my local stations. >> I need the resonance peaking to see the signal. >> >> What diameter PVC? >> >> I have 1/2" OD polystyrene that will allow a little closer coupling >> between the ferrite and the wire. 400 turns #28 = 203uh air core. >> >> I have 1/2" CPVC. actual OD. 0.615" >> 290 turns #28 = 200uh air core >> >> >> I have 1/2 PVC, actual OD. 0.832. 175 turns #28 = 205uh air core. >> >> Pick one. >> >> I'll also wind one with less turns and use my best Q rod that is 8" long >> x 0.375" diameter. >> >> I will check three frequencies, 590Khz, 1290kHz and 1430Khz. >> >> I made a post last night of the wrong experiment (6"dia not 6" long) >> It has not shown up this morning, so I'll repeat my measurement method. >> >> To measure the signal I have a very high input impedance amp with a >> gain of 1. >> I use the amp to drive a scope (ch 2) set at 50mV/div. I took the >> channel 2 output from the back of the scope to drive a Boonton 92BD RF >> millivolt meter. I use the scope to compare the visual to audio from a >> portable radio to know where I am tuned. >> Modulation causes a bit of amplitude bounce, but I do a visual average. >> >> Let me know what you want. >> Mikek >> >> >> --- >> This email has been checked for viruses by Avast antivirus software. >> https://www.avast.com/antivirus >> > > > Please do not use PVC as RF insulation or support pieces. > It is lossy to extremely lossy at RF. > Plasticized PVC ain't stellar but not horrid. http://g3ynh.info/zdocs/comps/part_6.html Or do they add a lot of vispipuuro into the mix in Finland? :-) -- Regards, Joerg http://www.analogconsultants.com/
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-03-24 13:59 -0400 |
| Message-ID | <ob3mkk$m2c$1@dont-email.me> |
| In reply to | #453418 |
On 3/24/2017 1:14 PM, Joerg wrote: > On 2017-03-20 02:06, Tauno Voipio wrote: >> On 19.3.17 15:20, amdx wrote: >>> On 3/14/2017 11:18 PM, billbowden wrote: >>>> Which is a better design. Suppose you have a 6 inch length of PVC pipe >>>> with >>>> numerous turns of wire that has an inductance of say 200uH. Now >>>> suppose you >>>> use the same (6 inch) piece of PVC with a ferrite rod in the core with >>>> considerably fewer turns of wire. Which one would capture the most >>>> signal >>>> at the AM Broadcast frequencies (500K to 2 Megs) and produce the >>>> greatest >>>> signal output? Would it be more ferrite, or more wire? >>>> >>> >>> I'll run the experiment. >>> >>> Do you want it tuned? >>> >>> If not, I have no way to measure the signals of my local stations. >>> I need the resonance peaking to see the signal. >>> >>> What diameter PVC? >>> >>> I have 1/2" OD polystyrene that will allow a little closer coupling >>> between the ferrite and the wire. 400 turns #28 = 203uh air core. >>> >>> I have 1/2" CPVC. actual OD. 0.615" >>> 290 turns #28 = 200uh air core >>> >>> >>> I have 1/2 PVC, actual OD. 0.832. 175 turns #28 = 205uh air core. >>> >>> Pick one. >>> >>> I'll also wind one with less turns and use my best Q rod that is 8" long >>> x 0.375" diameter. >>> >>> I will check three frequencies, 590Khz, 1290kHz and 1430Khz. >>> >>> I made a post last night of the wrong experiment (6"dia not 6" long) >>> It has not shown up this morning, so I'll repeat my measurement method. >>> >>> To measure the signal I have a very high input impedance amp with a >>> gain of 1. >>> I use the amp to drive a scope (ch 2) set at 50mV/div. I took the >>> channel 2 output from the back of the scope to drive a Boonton 92BD RF >>> millivolt meter. I use the scope to compare the visual to audio from a >>> portable radio to know where I am tuned. >>> Modulation causes a bit of amplitude bounce, but I do a visual average. >>> >>> Let me know what you want. >> >> >> Please do not use PVC as RF insulation or support pieces. >> It is lossy to extremely lossy at RF. >> > > Plasticized PVC ain't stellar but not horrid. > > http://g3ynh.info/zdocs/comps/part_6.html > > Or do they add a lot of vispipuuro into the mix in Finland? :-) Are you reading the same page? It says PVC Tanδ is 0.04 - 0.14 at 1 MHz. That is in no way acceptable for the sort of high Q circuits that are being discussed. That's comparable to wood, 0.059. This page even lists PVC in the "Lossy" group as defined by Tanδ ≥ 0.01. -- Rick C
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