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[AMPS] screen voltage supply

To: <amps@contesting.com>
Subject: [AMPS] screen voltage supply
From: n6tr@teleport.com (Larry Tyree)
Date: Fri, 18 Jul 1997 06:26:22 -0700 (PDT)
> Has anyone tried tapping off of the B+ via a dropping resistor to provide
> screen voltage to a tetrode? 

Hi Lane-

I have seen this technique discussed and used for some low power 
transmitters.

100 ma is a lot to do this with (depending on the voltage drop you
need).  For example, 2KV at 100 ma is quite a bit of heat to have
(unless you live in Alaska).  Also, you will probably need a voltage
regulator of some kind (nice blue glowing tubes can be purchased 
surplus for about $1 each).  The reason for this is that you will
have poor regulation due to the high impedance of the divider
otherwise.  However, these tubes are only good for about 40 ma max
and are more typically run around 10 to 20 ma.

I am not sure of the type of amplifer you are talking about, but 
100 ma would suggest it is something pretty powerful.  If you had
said 10 ma, then this approach might be more attractive, but 100 ma
sounds too big (to me).

73 Tree N6TR
tree@contesting.com

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