[MRCG] Need BC-375-E advice

[Richard Knoppow]

-----Original Message-----
>From: "Falls, Jim at DOC" <Jim.Falls at conservation.ca.gov>
>Sent: Jan 10, 2014 10:14 AM
>To: West Coast Military Radio Collectors Group <mrcg at mailman.qth.net>
>Subject: Re: [MRCG] Need BC-375-E advice
>
>I didn't check the actual antenna contacts. Concentrated on the keying contacts deep inside the main relay. 
>
>Running the filaments at 1/2 power right now with a variac ahead of the PSU. Will bump them up to full power this afternoon. Not sure if this is an Old Ham's Tale, but figured I'd give it a try rather than slam these NOS tubes with full filament power after so long in storage.
>
>Feel a tad silly, but 211's that won't oscillate in this rig will still work OK as amplifiers/modulators, correct?
>
>73 DE JIM K6FWT

       The 211 uses thoriated tungsten filaments. It won't hurt them to run at low voltage when there is no voltage on the plates but also serves no purpose.  Thoriated tungsten filaments should be run very close to the specified voltage.  RCA and Eimac recommend within +/- 5%   Tubes with long operating times can lose some emission. They can often be brought back, at least for a while, but running the filaments overvoltage.  I think Eimac published the method.  This causes some of the thorium in the filament to boil to the surface.  
     I'm not sure about the oscillator vs: amplifier characteristics of the tubes.
     My BC-375E was modified to run from an external exciter, I think I didn't even have a tube in the socket.  I have to rescue this thing from storage one day and see if it still works. I did have it rigged to use the keying relay just as a transmit relay and keyed the exciter.