[Amps] 8877 Grid Connection DC or Not

[Jim Thomson]

Date: Tue, 29 Nov 2016 17:37:27 -0600
From: "Jim W7RY" <jimw7ry at gmail.com>
To: "Radio WC6W" <wc6w_amps at yahoo.com>, "AMPS" <amps at contesting.com>
Subject: Re: [Amps] 8877 Grid Connection DC or Not

Marv... Because this will be a single power supply and multiple RF deck (5 
or 6 of them) amplifier system for a contest station.  I dont want to use 
vacuum relays as high voltage switches.

Metering plate current is easy. Simply put the plate current meter (set back 
from the front panel for safety) in series with the HV on the RF deck.

Thats why.

Thanks
73
Jim W7RY


##  There was some minor trick to this scheme, that I worked out a few years back for
somebody else.  I will try and dig up my old notes.  It used one big B+ supply, connected
to  6 x amps.  Each amp used the same type tube.  Each RF deck had its own fil xfmr, and
its own plate / grid / HV meter.  

##  If I recall, the B+  was fed to the 6 x amps in the normal fashion.  Ditto with the B-. 
Plate current in each RF deck was measured in the normal way, ditto with grid current.
IE: B-  coming into back of rf deck fed to NEG of plate current meter. POS of plate 
current meter bonded to POS of grid current meter.  NEG of grid current meter bonded to
chassis.  POS of both grid + plate meter fed towards  CT of fil xfmr.  Usual 50-100k resistor
in series with the CT, with TR contacts across it.  HV meter in each RF deck was wired directly between
incoming B and B-. 

## RVS connected 6A10  diodes wired between B-  and chassis...in  HV supply.  Then the B- cant wander more than  
+/-  .7 volt. 

Jim   VE7RF