[Milsurplus] GRC-9 question

[Dennis DuVall]

Hue,

Good question, the manual describes the circuit but doesn't say why.

By doing it the way they did the load on the receiver filament circuit  
remains unchanged when the pilot light is lit.  Normally one would  
turn on the light to read or set the receiver frequency. It may be  
that throwing  an additional load on the receiver filament supply by  
switching in the light IN ADDITION to the load represented by the  
tubes would change the receiving frequency by some amount giving an  
error in the receiver frequency setting as soon as the light was  
turned off.  My best guess anyway.

Dennis D, W7QHO
Glendale, CA

******************

On Feb 18, 2015, at 11:40 AM, Hue Miller wrote:

> Say, a question on GRC-9 schematic.The pilot lamp circuit - why does  
> it switch out 1/2 the 3V4 heaterwhen the pilot lamp is engaged? Only  
> reason i can think of, is you're olusing a well-used receiver  
> battery, and the voltage might go down( change ) when otherwise you  
> push the lamp button - and the filament voltage of the whole  
> receiver drops, and the frequencyof the weak CW signal you're  
> searching for changes.....???What say?tnxHue Miller  		 	   		
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