[Milsurplus] BC-348-J BFO Help Needed (Corrected)

[Bruce Gentry]

Check the  resistor and it's connections between the grid and cathode of 
the 6SR7. If it has gone really high or opened up, the oscillator won't 
start. The meter used to measure the voltages can act as a substitute 
for the bad resistor. Because the BFO works well when the grid pin is 
touched with the meter probe, the other components in the circuit are 
probably good. If you are using a power supply to replace the dynamotor, 
be sure the negative side of the B supply is not grounded, it "floats" 
to produce bias for the audio output stage and other circuits.

     Bruce Gentry, KA2IVY


On 1/2/19 10:24 PM, Joe Connor via Milsurplus wrote:
> Guys, I need some help and advice for a BC-348-J I'm working on. The 
> link for the manual is below (AN 08-10-112) and the schematic is on 
> pp. 75-76.
>
> My problem is no BFO. With the BFO switch on, the voltages look pretty 
> good, but no BFO. While I was doing the voltage testing, I found that 
> when my probe touches the grid (pin 2) of the 6SR7 (2nd Det/CW Osc.) 
> with the BFO switch on, I get the BFO loud and clear. With the probe 
> on but the BFO switch off, I don't get the BFO tone.
>
> Any ideas? >From the results above, I assume I can rule out the BFO 
> oscillator, the 6SR7 and the BFO switch as the culprits. What else is 
> there?
>
> This receiver is pretty nice. No mods and I have the shock mount, so 
> I'd really like to get it going full blast.
>
> As always, thank you for your help.
>
>                             Joe Connor
>
>
>
> http://bama.edebris.com/manuals/military/bc348/
>
>
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