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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: Binocular choke extras
Date: Thu, 20 Mar 2025 23:55:45 +0100
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On 3/20/25 21:15, Don wrote:
> Don wrote:
>> Jeroen Belleman wrote:
>>> Don wrote:
> 
> <snip>
> 
>>>> It's difficult for me to follow this conversation. Maybe my followup
>>>> simply repeats what you guys already said.
>>>>       The tubes are shields designed to fit inside the binocular core
>>>> holes. You then soldier them together with a PCB at each end like so:
>>>>
>>>>       <https://www.qsl.net/g3oou/BBTrans_4278a.jpg>
>>>>
>>>> It becomes more interesting with coax:
>>>>
>>>>       <https://www.qsl.net/kf8od/ldmos53.jpg>
>>>
>>> Not at both ends! That is not going to work!
>>
>> What you say makes sense in retrospect.
> 
> In retro-retrospect what you say doesn't make sense. Is
> <https://www.qsl.net/kf8od/ldmos53.jpg> wrong? It says to solder both
> ends.

That one is OK. The tubes connect on one end, but not on the other.
There's a gap between the sides in the bottom picture. It will work,
though if I were to make it, I wouldn't bother using coax for the
high-impedance winding.

> 
> What flummoxes me is why shielded coax is is itself inserted into a
> separately shielded sleeve?

Agreed. The coax shields are simply in parallel with the single-turn
low-impedance winding formed by the tubes. Maybe it shifts the upper
cut-off frequency a tiny bit upwards, but I'm not convinced it's worth
the trouble.

Jeroen Belleman