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Today's Topics:

   1. BC-946B restore (n3lll --)


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Message: 1
Date: Fri, 2 Aug 2024 12:30:15 -0500
From: n3lll -- <n3lll@kitparts.com>
To: ARC-5 <arc5@mailman.qth.net>
Subject: [ARC5] BC-946B restore
Message-ID:
        <CAJ0n1F9nDXhmVZs3uwVirxBUUVxcQTTZioem7JJLE23uF4KUwA@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

I picked up a clean BC-946B radio a few weeks ago.  Yesterday I set about
restoring it, it was a lot bigger job than most.  As is in many 80 year old
Command sets someone in its life hacked around in it.  One of the changes
was the addition of a standard output transformer, which I retained.  The
front shroud was also removed so I had to extend wires into the front of
the radio and construct  a shield for the RF input to the RF amp grid.
Then I cleaned up the prior modifier's crappy wiring.

I usually spot check resistors prior to conversion, in many cases they
are off but still close to tolerance, in the case of this radio almost all
the resistors required change.  This also included the resistors in the RF
cans.  I also found the mica capacitor on the grid of the RF amplifier to
be 10PF  rather than 100PF.  While I had the cover off I lubricated the
bearings and worm gear.  Once that was complete I rewired the filaments for
12 volts and used my Kitparts capacitor replacement kit to replace the
capacitors.  I also loosen and retighten the 8 screws holding the resistor
terminal blocks, in the case of this radio it made a big improvement in the
noise level.  I am sure there has been a lot of expansion and contraction
since those screws were last screwed in 80 years ago.

It is always encouraging when the radio comes up working!  My bench test
here in Houston is to tune in WWL in New Orleans, which is over 350 miles
away.

Best Regards ... tom, N3LLL
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End of ARC5 Digest, Vol 247, Issue 1
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