[Milsurplus] GRC-9 question

[Richard]

The answer is obviously yes. Maintaining close to the same filament 
current when the lamp is lit minimizes frequency shift when filament 
voltage shifts.  Note that the filament voltage is regulated by 
forward-conducting selenium cells, more or less.  My GRC-9's use two 
silicon rectifier elements forward conducting for regulation, which 
works pretty well, but when I push the lamp button frequency shifts 
about 150 cycles.  That's not bad, but maybe a regulator chip would be 
better.

Richard, AA1P


On 02/18/2015 02:40 PM, 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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