[ARC5] [External Sender] Re: BC-348-R Update

[Dennis Monticelli]

Ooops.  Forgot to say that a DC blocking cap should be added in series.  So
something like 0.01uF/500V along with the 100K.

Dennis AE6C

On Thu, Aug 18, 2022 at 6:45 AM Bill Henderson <bill.henderson at ocdsb.ca>
wrote:

> SUPER IDEA !!!
>
>  - Bill H. / va3hwa
>
>
>
> [image: Mailtrack]
> <https://mailtrack.io?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality11&> Sender
> notified by
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> <https://mailtrack.io?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality11&> 08/18/22,
> 09:44:07 AM
>
> On Thu, Aug 18, 2022 at 9:40 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> 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]
>>> 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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