Date: Thu, 9 Sep 2010 19:38:00 -0800
From: Jim W7RY <w7ry@inbox.com>
Subject: Re: [Amps] GS35B questions
Great idea....
I too am using 2 resistors for the HV return in my 8877 project. I wanted to
have a resistor in the power supply as well as in the RF deck. I used a 2K in
the power supply and a 2k in the amplifier chassis. The metering circuit takes
the ground resistance down to a few ohms in the RF deck.
I'm using the WD7S triode board setup and analog Simpson meters.
73
Jim W7RY
## why make the metering more complicated than it has to be ? Esp for a GG
triode.
## B- from HV supply goes to NEG terminal of plate current meter. POS
terminal of plate current meter goes to
POS terminal of of grid meter. Those 2 x POS goes to cathode. [ via bias
diodes + RX cut off resistor] NEG terminal of grid meter goes to chassis.
I usually insert a FAST 3agc fuse
[ reap apron mount].... between chassis, and NEG terminal of grid meter. [
nothing goes across the grid fuse]
## You can also install a FAST 3agc cathode fuse in series with the RF cut
off resistor. Then shunt the cathode fuse with a pair of 100 k -3 watt mof
resistors.
## do the safety diodes as Bill WRT describes. I use 2-4 x 6A10's in each
direction... then the surge rating is 800-1600A. Then you never replace em.
## Putting RVS connected 6A10's directly between B- of hv supply.. and HV
chassis insures that the B- can never 'wander' more than +/- .7 v from
chassis potential. Then BOND the chassis of the RF deck to the HV chassis !!
## Use a big 50 ohm, high wattage glitch R and a B+ HV fuse..and you are
covered. [ fuse goes 1st, THEN the glitch R] Then you can
Cro-bar anything you want after that..and nothing will blow up. For added
assurance, install a 2nd HV fuse, between plate xfmr sec.. [either leg]
and diode rectifier board. [ FWB or FWD]
later... Jim VE7RF
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