[Milsurplus] TCS: T-17 and RS-38 Microphone Mystery

[WA5CAB at cs.com]

In any given radio set anyway, the mic supply voltage at the top of the 
modulation transformer primary is the same (more or less) whether you have it 
set to run off of a 6V, 12V or 24V system.  The primary voltage selector 
switch, among other things, switches in additional resistors upstream of the 
transformer to make this so.  

In a message dated 12/21/2015 13:57:48 PM Central Standard Time, 
antqradio at sbcglobal.net writes: 
> I thought about the carbon microphone current bias too but I figured that 
> the cathode bias voltage would be lower then the filament voltage assuming 
> (here we go again) that filament voltage was 28 volts.  My thought was 
> that the transformer turns ratio was high enough to properly drive the 
> modulator tube grids, i.e. tens of volts.  I have gone no further then make a 
> guess that this is the case so I could be way off base.
> 
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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