[ARC5] BC-454-B, tough problem

J Mcvey ac2eu at yahoo.com
Fri Nov 18 23:19:10 EST 2016


I had a similar issue a while back. Note that the tuning gang is in the oscillator PLATE circuit. It was the the variable cap that was bringing down the plate.I blew it out with an air compressor to clear the short. 
It may have been a  growth from the metal or just a stray shard. I never saw the culprit.
 

    On Friday, November 18, 2016 4:54 PM, WA5CAB--- via ARC5 <arc5 at mailman.qth.net> wrote:
 

 Not that it would appear to have had anything to do with the problem,. but the only lead going through the tuning capacitor covver is the mixer grid lead.

In a message dated 11/18/2016 15:04:18 PM Central Standard Time, ianmwilson73 at gmail.com writes: 

I've been resurrecting a BC-454; everything worked FB except for the local
oscillator stage (triode part of the 12K8 triode-hexode).


The triode plate voltage appeared to be absent. This part of the circuitry
is a little obscure, since there is a 200k plate series resistor that is contained
in the RF oscillator subunit of the plug-in coil thingy. Also, the plate supply
for this stage is routed through the capacitor cover.




Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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