Groups > sci.electronics.design > #433776

Re: 50 ohms to 0.02 ohm transformer

From	amdx <nojunk@knology.net>
Newsgroups	sci.electronics.design
Subject	Re: 50 ohms to 0.02 ohm transformer
Date	2016-11-03 20:36 -0500
Organization	A noiseless patient Spider
Message-ID	<nvgon4$bsu$1@dont-email.me> (permalink)
References	<nvfc2s$6r6$1@dont-email.me> <nvfd3r$aj5$1@dont-email.me> <4aum1c1gog519isp42g1hhcac03beg96ki@4ax.com> <nvgbpq$1hc$1@dont-email.me>

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On 11/3/2016 4:56 PM, amdx wrote:
> On 11/3/2016 12:55 PM, John Larkin wrote:
>> On Thu, 3 Nov 2016 15:12:53 +0200, Tauno Voipio
>> <tauno.voipio@notused.fi.invalid> wrote:
>>
>>> On 3.11.16 14:55, 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
>>>
>>> For a toroid, a turn is simple: A wire through the toroid
>>> hole is a turn, a wire outside is nothing.
>>>
>>> IMHO, your real problem is on the 20 milliohm side to make
>>> the circuit connections so that you're not going to lose all
>>> of your signal in the connection resistances and inductances.
>>> This is regardless which way you build your transformer.
>>
>> Leakage inductance can matter.
>>
>> It would be interesting to make a toroidal transformer where the
>> 1-turn winding wraps around the entire core. Visualize that! It can be
>> approximated by paralleling multiple 1t windings.
>>
>> http://www.spaceneedle.com/wp-content/uploads/2013/08/view-from-heli-250x211.jpg
>>
>>
>>
>
>
>   Hows this John,
>
>> https://www.dropbox.com/s/6klg2v2awamchb5/2001-12-31%2023.00.00-122.jpg?dl=0
>>
>
>> https://www.dropbox.com/s/3gmnukf4u7kawx3/2001-12-31%2023.00.00-120.jpg?dl=0
>>
>
>  I haven't tested it yet.
>
>                           Mikek

  My transformer, with the one turn winding open, looks great.
10vpp in 200mvpp out exactly 50 to 1 ratio.
However, when I load it with  0.02 ohms (a 15 in wire)
it barely changes amplitude, and the primary amplitude also doesn't 
change. If 50 ohms was reflected back it would drop by 1/2.
  Shorting the secondary one turn with a pair of needle nose pliers
drops the secondary voltage about 10%.
  Time to sleep on it.
                       Later, Mikek

Thread

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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