Re: [MRCA] WTB Mod. Transformer for TBW (Suppressor Grid Modulation)

[W7QHO at aol.com]

In a message dated 2/7/06 4:45:29 AM, JOHNGRU at aol.com writes:


> I need a suppressor grid modulation transformer for my TBW HF RF deck. The 
> tube to be modulated is an 803. (The modulator was in the Power supply for 
> the 
> TBW).
> 
> ? I have an extra mod. xformer for my GF-11 (Finals are 2 837s) which might 
> work?? Does anyone know the +/- voltage range needed to fully modulate the 
> 803??
> 

John,

My TBW and GP-7 manuals list the 803 suppressor grid bias for voice 
conditions as being -110 volts.   For 100% modulation a peak-to-peak voltage swing of 
twice this (220V P-P) would be a good place to start.   The suppressor grid 
draws no current so the modulator delivers no power; a simple voltage amp. and 
audio transformer should do the job.

Dennis D. W7QHO
Glendale, CA