[Milsurplus] GRC-9 question

[Hue Miller]

Yes,  i noticed that last nite while looking at the manuals. I felt like giving the BC-1306 service manualwriters hell: they could easily have numbered the pins on the sketches of the equipment showing connectors - and maybe purpose - i'm thinking especially of the interconnect rec-trans cable. Also,why not actually label the equipment for interconnect pins and voltages?My surmise about the lamp circuit is same as Dennis's.  BTW, i puzzled over the 1306 trans output circuit too. I found the drawing and notes for the antennaselector switch pretty unhelpful. So another project will be to redraw it, all conditions shown. User doesn't have to know that much, i suppose. -Hue 

> From: mmab at cox.net
> To: duvallddennis at gmail.com; kargo_cult at msn.com
> CC: armyradios at yahoogroups.com; milsurplus at mailman.qth.net
> Subject: Re: [Milsurplus] GRC-9 question
> Date: Wed, 18 Feb 2015 16:03:21 -0800
> 
> 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
> -
> -
> 
> ----- 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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