[ARC5] BC-348-R Update

[Bobby Drummond]

That’s a great, practical idea, Dennis.  Thanks for letting us in on that one.


73 de Bobby D - AK4JA

> On Aug 18, 2022, at 9:39 AM, Dennis Monticelli <dennis.monticelli at gmail.com> wrote:
> 
> FYI.  An old powered computer speaker works as a signal tracer.  Put a 100K resistor in series with its medium Z input for audio tracing.  Add a diode for IF detection. 
> 
> Dennis AE6C
> 
> On Thu, Aug 18, 2022 at 1:10 AM Robert Downs via ARC5 <arc5 at mailman.qth.net <mailto:arc5 at mailman.qth.net>> wrote:
> Jim, you might want to check the B- bias line running from the B- dynamotor brush holder through to the grid of the audio output tube.  It should be only a few volts below ground. 
> 
> Robert Downs
> 
> -----Original Message-----
> From: arc5-bounces at mailman.qth.net <mailto:arc5-bounces at mailman.qth.net> [mailto:arc5-bounces at mailman.qth.net <mailto:arc5-bounces at mailman.qth.net>] On Behalf Of JAMES FALLS
> Sent: Thursday, August 18, 2022 02:14
> To: milsurplus; ARC5
> Subject: [ARC5] BC-348-R Update
> 
> Still dead. 
> 
> I replaced all the leaky can caps, the burnt resistor and suspect 240pF cap in the 2nd IF can. No leakage at the tie point detected per Dave’s recommendation, but it’s still silent. 
> 
> Dynamotor sounds happier/quieter, and I get a faint “tick” when I switch the BFO on or off, so at least the audio is working. DIal lights are OK. 
> 
> Ran it with the BC-375 in SPOT mode like I’d do to zero on a station. Didn’t hear a thing, and the 375 was putting out its usual 50W. 
> 
> I’m going to pull it from the cabinet again, recheck all the tubes, install the relay jumper,  go thru the resistance tables, hotwire it so I can measure voltages and see what turns up. Start working back from the AF stage. Wish I’d already restored that old Signal Tracer. Fake it with my Eico or LM-13. 
> 
> At least no hot smell or crackling when I pulled the chassis after running a couple minutes or so. Just warm MFP. 
> 
> More later. Think I’ll let it sit a few days. Let my brain cool down. 
> 
> Jim Falls K6FWT 
> 
> 
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