Morning Jim,
I'm looking at the schematic on Dominic web page <
http://f1frv.free.fr/main1n_Triode_Linear_Amp.html >, to the " Fet Cathode
Control & Meters " and " Different Tubes Arrangement " images, and just
looking at it can't see any difference.
Chris also here transformers are very expensive, and few shops to make
them.
2015-02-04 11:50 GMT+00:00 Jim Thomson <jim.thom@telus.net>:
> Date: Wed, 4 Feb 2015 11:00:58 +0000
> From: Nuno Lopes <ct2iry@gmail.com>
> To: Chris Wilson <chris@chriswilson.tv>
> Cc: amps@contesting.com
> Subject: Re: [Amps] D.C. on filaments of GS-35B?
>
> Morning Chris,
>
> I know Dominic is using Vdc on the filament, so other guys in France are
> using those power supply or PC power supply to feed filament and relays ,
> that's the reason that I was asking.
>
> Any special care when feeding with Vdc?
>
> ## The real trick is that you need to return the cathode current back to
> the cathode.
> The normal deal with a xfmr is to use a fil xfmr with a CT in the
> secondary. The
> B- from the hv supply 1st flows to the neg side of the plate current
> meter. Neg side
> of grid meter is bonded to chassis. ¨Positive of both grid + plate meter
> are tied together,
> and then routed through the normal 50k cut off resistor, then through the
> bias..then to the
> CT of the fil xfmr sec. From there its off to the fil / cathode. B+
> of course goes to the
> anode...completing the loop.
>
> ## IF dc is used from say a switching supply, you still have the
> requirement to get the
> dc cathode current back to the cathode. And that doesn’t mean tying it
> to one side of the
> fil either.
>
> Jim VE7RF
>
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>
--
*73 Nuno CT2IRY*
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