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Groups > sci.electronics.design > #433628
| From | amdx <nojunk@knology.net> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: 50 ohms to 0.02 ohm transformer |
| Date | 2016-11-03 09:57 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <nvfj7f$244$1@dont-email.me> (permalink) |
| References | <nvfc2s$6r6$1@dont-email.me> <nvffqd$sjv$1@gioia.aioe.org> |
On 11/3/2016 8:58 AM, Jeroen Belleman wrote:
> On 2016-11-03 13:55, amdx wrote:
>> I want to build a 50 ohm to 0.02 ohm transformer.
>> It needs a 50 to 1 turns ratio.
>> It takes a low A sub L core to make such a thing.
>> I have a toroid with an A sub L of 75. That only needs
>> 29 turns for my frequency of interest 500KHz to 1700kHz.
>> I also have some potcores that I could gap to lower the A sub L.
>>
>> What would make a better transformer a toroid or a gapped potcore?
>>
>> I plan 50 turns with a 1 turn secondary.
>>
>> What problems can I expect with a 1 turn secondary?
>>
>> Thanks, Mikek
>
> A bandwidth ratio of only three should be dead-easy,
> but the 20 mOhm impedance may spell trouble.
> The single-turn winding should be fat and compact.
> A single nH of stray inductance (!) or ten mOhms
> of resistance would ruin performance. I think I would
> implement it as several single-turn windings in parallel,
> distributed around a toroid. What will you connect
> to the 20mOhm side?
A 20mOhm resistor.
I'm replacing a tube osc, I'm not able to follow the coax back to the
tube output on the schematic, so I don't even have a start to figure out
the tube output impedance. I'm starting to think it is not low.
But it is able to drive 1 amp through the 0.02 ohm resistor to develop
20mv.
> Why would you need low A_l? The usual rule of having the
> reactance of one winding four times the terminal impedance
> is only a minimum. There is no harm in going higher. There
> would be if you did it by using more turns though.
>
My calculations tell me that with an AsubL of 75 it take 29 turns.
This still doesn't get my a 50 to 1 turn ratio.
If I use a core with an AsubL of 2340, I only need 5 turns, with that I
can't get a 50 to 1 turns ratio.
> Use a toroid. Gapped cores are for energy storage,
> not for transformers.
>
> Jeroen Belleman
I'll restate my problem,
I want to substitute a more stable signal generator for the internal
signal generator in my Boonton 260A Q meter. The osc. in the 260A drives
a 0.02 ohm resistor. It actually does this through a piece of coax,
so I doubt it really has a 0.02 ohm output impedance. Could be I'm
chasing a spec. I don't need to.
One advantage I have is I only want 4mv of drive across the 0.02 ohm
resistor, also I can adjust the signal generator output to set the
voltage regardless of transformer/connection losses.
Thanks for the multiple single turn winding in parallel idea.
Still open to suggestions,
Thanks, Mikek
PS.
Next project is an RF detector to measure the 4mv signal, I want a
circuit to drive my multimeter. I suspect I'll need a preamp before the
detector to get any linearity. I do have a scope I can use to get a
useful calibration.
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50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 07:55 -0500
Re: 50 ohms to 0.02 ohm transformer Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-11-03 15:12 +0200
Re: 50 ohms to 0.02 ohm transformer John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-03 10:55 -0700
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 16:56 -0500
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 20:36 -0500
Re: 50 ohms to 0.02 ohm transformer Syd Rumpo <usenet@nononono.co.uk> - 2016-11-08 23:35 +0000
Re: 50 ohms to 0.02 ohm transformer Lasse Langwadt Christensen <langwadt@fonz.dk> - 2016-11-08 15:51 -0800
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-08 21:45 -0600
Re: 50 ohms to 0.02 ohm transformer Jasen Betts <jasen@xnet.co.nz> - 2016-11-10 03:28 +0000
Re: 50 ohms to 0.02 ohm transformer Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-11-04 10:41 +0200
Re: 50 ohms to 0.02 ohm transformer Jeroen Belleman <jeroen@nospam.please> - 2016-11-04 10:54 +0100
Re: 50 ohms to 0.02 ohm transformer bill.sloman@ieee.org - 2016-11-04 06:00 -0700
Re: 50 ohms to 0.02 ohm transformer Jeroen Belleman <jeroen@nospam.please> - 2016-11-04 14:10 +0100
Re: 50 ohms to 0.02 ohm transformer John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-04 08:08 -0700
Re: 50 ohms to 0.02 ohm transformer "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-11-04 22:13 -0500
Re: 50 ohms to 0.02 ohm transformer Jeroen Belleman <jeroen@nospam.please> - 2016-11-03 14:58 +0100
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 09:57 -0500
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 09:59 -0500
Re: 50 ohms to 0.02 ohm transformer Tim Wescott <seemywebsite@myfooter.really> - 2016-11-03 11:56 -0500
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 12:15 -0500
Re: 50 ohms to 0.02 ohm transformer Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-11-03 19:37 +0200
Re: 50 ohms to 0.02 ohm transformer makolber@yahoo.com - 2016-11-03 10:49 -0700
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 13:19 -0500
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 13:31 -0500
Re: 50 ohms to 0.02 ohm transformer Tim Wescott <seemywebsite@myfooter.really> - 2016-11-03 14:38 -0500
Re: 50 ohms to 0.02 ohm transformer Tim Wescott <seemywebsite@myfooter.really> - 2016-11-03 14:39 -0500
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-03 16:52 -0500
Re: 50 ohms to 0.02 ohm transformer whit3rd <whit3rd@gmail.com> - 2016-11-03 18:00 -0700
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-04 06:26 -0500
Re: 50 ohms to 0.02 ohm transformer Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-11-04 15:20 +0200
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-04 09:33 -0500
Re: 50 ohms to 0.02 ohm transformer Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-11-04 21:21 +0200
Re: 50 ohms to 0.02 ohm transformer "tom" <tmiller11147@verizon.net> - 2016-11-03 14:02 -0400
Re: 50 ohms to 0.02 ohm transformer Winfield Hill <hill@rowland.harvard.edu> - 2016-11-03 10:25 -0700
Re: 50 ohms to 0.02 ohm transformer Jeff Liebermann <jeffl@cruzio.com> - 2016-11-04 11:24 -0700
Re: 50 ohms to 0.02 ohm transformer Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-11-04 21:24 +0200
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-04 16:46 -0500
Re: 50 ohms to 0.02 ohm transformer amdx <nojunk@knology.net> - 2016-11-05 12:37 -0500
Re: 50 ohms to 0.02 ohm transformer mike <ham789@netzero.net> - 2016-11-05 02:29 -0700
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