[Boatanchors] BC-312/342 audio problem

[Joe Connor]

Ian:

     Did you replace that one cap (.01?) lurking behind the panel between the 6F6 tube and the panel? That's an easy one to miss, and it's a usually a notoriously unreliable Micamold. I believe it's an audio cap.

                                    Joe Connor



>________________________________
> From: Ian Wilson <ianmwilson73 at gmail.com>
>To: Boatanchors <boatanchors at mailman.qth.net> 
>Sent: Tuesday, July 23, 2013 10:02 AM
>Subject: [Boatanchors] BC-312/342 audio problem
> 
>
>I've recapped this radio, apart from the AGC decoupling
>caps in the RF/mixer cans.
>
>Have replaced a few underperforming VT-86's and aligned
>the IF stages and the RF stages on 40m.
>
>Everything is basically working. However, the audio is poor,
>with a lot of high-frequency noise and distortion above about
>75% on the volume control. Both MVC and AVC are like this
>but behave somewhat differently. Voltages on the RF gain
>pot and the various grids all check out OK as I vary the gain
>in the two modes.
>
>The audio is poor both on AM and SSB. I should look for an
>audio signal source, I guess, to check out the audio stages on
>their own. Am using an audio output transformer of unknown
>impedance ratios to a decent speaker.
>
>Anything obvious I should look for?
>
>73, ian K3IMW
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