[Milsurplus] GRC-9 question

[Michael Bittner]

BTW, I see the that the AN/GRR-5 does the same thing with the dial light, 
but the BC-1306 does not.  Strange?!

Mike, W6MAB
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----- Original Message ----- 
From: "Dennis DuVall" <duvallddennis at gmail.com>
To: "Hue Miller" <kargo_cult at msn.com>
Cc: <armyradios at yahoogroups.com>; <milsurplus at mailman.qth.net>
Sent: Wednesday, February 18, 2015 3:30 PM
Subject: Re: [Milsurplus] GRC-9 question


> 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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