[ARC5] ARC5 Digest, Vol 247, Issue 1

[Matt P]

Nice work as always Tom.

On Fri, Aug 2, 2024, 13:30 <arc5-request at mailman.qth.net> wrote:

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> Today's Topics:
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>    1. BC-946B restore (n3lll --)
>
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 2 Aug 2024 12:30:15 -0500
> From: n3lll -- <n3lll at kitparts.com>
> To: ARC-5 <arc5 at mailman.qth.net>
> Subject: [ARC5] BC-946B restore
> Message-ID:
>         <
> CAJ0n1F9nDXhmVZs3uwVirxBUUVxcQTTZioem7JJLE23uF4KUwA at 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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