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From: antispam@fricas.org (Waldek Hebisch)
Newsgroups: sci.electronics.design
Subject: Re: Grounded grid VHF front-end
Date: Mon, 18 Nov 2024 23:49:33 -0000 (UTC)
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Edward Rawde <invalid@invalid.invalid> wrote:
> "Jan Panteltje" <alien@comet.invalid> wrote in message news:vgq37s$oo9h$1@solani.org...
>> On a sunny day (Sun, 10 Nov 2024 09:51:49 -0000 (UTC)) it happened Cursitor
>> Doom <cd999666@notformail.com> wrote in <vgpvnk$ao84$1@dont-email.me>:
>>
>>>On Sat, 9 Nov 2024 21:40:06 +0000, Liz Tuddenham wrote:
>>>
>>>> Cursitor Doom <cd@notformail.com> wrote:
>>>>
>>>> [...]
>>>>> There's not a single person on this group today who can really add any
>>>>> value here.
>>>>
>>>> You do them a dis-service, there are some people here who can think with
>>>> an open mind.  Even if the ideas they come up with wouldn't work, trying
>>>> to find out or explain why they wouldn't work is a good exercise and may
>>>> lead to a better solution than just asking hams what they have done
>>>> before.
>>>
>>>OK, that's entirely your call. But I think you'll find the number of
>>>people here with expertise in VHF receiver design is zero and the
>>>proportion of those with an adequate familiarity with designing for toobz
>>>is a vanishingly small subset of that figure. :)
>>>
>>
>> I designed plenty of VHF rx stuff, teefee works in that range,
>> including UHF.
>> But to go back in time and do it with toobs? No, I used transistors.
>> Only case I could think of for using toobs is when all semi-conductors
>> were destroyed by radiation.
>> But not much would be on air to listen for in that case.
>> And in that case shortwave would be a better place to listen for remaining lifeforms.
>> And grounded grid does not make a lot of sense, has not many advantages for a VHF input stage.
> 
> Why?
> https://www.google.com/search?&q=valve+fm+tuner&udm=2
> I can see at least two grounded grids and I don't recall a transistor FM tuner without a grounded base first stage.
> Reduced sensitivity was ofted caused by a need to replace that transistor because being the first stage it gets what the antenna 
> gets.

I have no experience with radio design, but for curiosity looked at
several early TV sets from soviet block.  _All_ tube circuits that
I found were common cathode in first stage, in late sixties apparently
they converged on caskode configuration (two early designs had
two common cathode stages).  I found also few early transistor
circunts, majority was common base, one was common emiter.  I
think reasonable guess is that tube characteristics make caskode
preferable, while for transitors (at least those from sixties and
seventies) common base seem to be better.

-- 
                              Waldek Hebisch