[Amps] GS35B questions

[Jim Thomson]

Date: Thu, 9 Sep 2010 19:38:00 -0800
From: Jim W7RY <w7ry at 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