Groups > sci.electronics.design > #431641

Re: Need clarification on RF related concepts

From	Jeroen Belleman <jeroen@nospam.please>
Newsgroups	sci.electronics.design
Subject	Re: Need clarification on RF related concepts
Date	2016-10-18 16:45 +0200
Organization	Aioe.org NNTP Server
Message-ID	<nu5chg$h1l$1@gioia.aioe.org> (permalink)
References	<c156ae15-c4bf-458f-8d1c-d3780a0f14ad@googlegroups.com> <nu20lk$8d2$1@dont-email.me> <nu52si$qrj$1@dont-email.me>

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On 2016-10-18 14:00, Tim Williams wrote:
> "rickman" <gnuarm@gmail.com> wrote in message
> news:nu20lk$8d2$1@dont-email.me...
>> The impedance of a transformer is not the inductive reactance of the
>> coils in the transformer.  A transformer reflects the circuit
>> connected to the secondary to the primary according to the turns
>> ratio.  The voltage and current scales by the turns ratio and the
>> impedance scales by the turns ratio squared.
>
> Of an ideal transformer, yes, but those aren't made with coils!
>
> All real transformers are transmission line transformers, and obey
> impedance matching rules, whether you like it or not.  Some are even
> constructed with transmission line theory in mind, and attain stupendous
> bandwidths as a result.[...]

I'm always on the look-out for stupendous-bandwidth transformers.
How wide is that? I'm aware of Sevick's work: Roughly 3 decades
of bandwidth. I want more!

I've managed to make inverting transformers, 1:4 transformers
and hybrids with 5 decades of bandwidth. These are made of
bits of straight UT-47 coax strung with Vacuumschmelze's tiny
amorphous tape-wound ISDN transformer toroid cores. Amazing
things, these little cores, though not without quirks.

I'd love to find a way to make similar performance 1:2
transformers, but my attempts have been disappointing up to
present. The limiting factors are the unwanted capacitance to
coax screens and the residual inductance of junctions. The
end of the manufacture of my favourite Vacuumschmelze
transformer cores has set me back by at least an octave, alas.
I now wish I'd bought more of them...

Jeroen Belleman

Thread

Need clarification on RF related concepts dakupoto@gmail.com - 2016-10-15 23:44 -0700
  Re: Need clarification on RF related concepts amdx <nojunk@knology.net> - 2016-10-16 04:37 -0500
  Re: Need clarification on RF related concepts Phil Allison <pallison49@gmail.com> - 2016-10-16 05:14 -0700
    Re: Need clarification on RF related concepts amdx <nojunk@knology.net> - 2016-10-16 08:04 -0500
  Re: Need clarification on RF related concepts Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-10-16 17:36 +0300
    Re: Need clarification on RF related concepts dakupoto@gmail.com - 2016-10-16 23:27 -0700
      Re: Need clarification on RF related concepts amdx <nojunk@knology.net> - 2016-10-18 08:44 -0500
        Re: Need clarification on RF related concepts Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2016-10-18 11:06 -0400
        Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-07 13:38 -0500
          Re: Need clarification on RF related concepts George Herold <gherold@teachspin.com> - 2016-11-07 11:00 -0800
            Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-09 18:35 -0500
              Re: Need clarification on RF related concepts Jeff Liebermann <jeffl@cruzio.com> - 2016-11-09 19:59 -0800
                Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-12 08:46 -0500
          Re: Need clarification on RF related concepts "nuny@bid.nes" <Alien8752@gmail.com> - 2016-11-07 11:09 -0800
            Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-09 18:22 -0500
  Re: Need clarification on RF related concepts Tim Wescott <tim@seemywebsite.really> - 2016-10-16 14:28 -0500
  Re: Need clarification on RF related concepts rickman <gnuarm@gmail.com> - 2016-10-17 04:04 -0400
    Re: Need clarification on RF related concepts "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-10-18 07:00 -0500
      Re: Need clarification on RF related concepts Jeroen Belleman <jeroen@nospam.please> - 2016-10-18 16:45 +0200
  Re: Need clarification on RF related concepts Jasen Betts <jasen@xnet.co.nz> - 2016-10-17 09:43 +0000

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