[ARC5] bc-950 vhf TX

[Robert Downs]

I once had about a dozen of the VHF transmitters.  Out of the bunch, one was
a BC-950-A, one had been a BC-950-A but was converted to T-23/ARC-5, and the
remainder were all T-23's when new.  I sold the BC-950 in 2005.

DC-30 was replaced by CR-1/AR which must have pretty quickly been replaced
by CR-1A/AR, which later became CR-1B.

Unlike the Maintenance Manual, where the LF/MF/HF were covered by AN
08-10-195 Volume 1 and the VHF by Volume 2, the Operator's Manual, NAVAER
08-5Q-95, covered both.  Reprints available.  

Robert Downs

-----Original Message-----
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of Mike Morrow
Sent: Sunday, November 18, 2018 19:26
To: ka9dzr at aol.com; arc5 at mailman.qth.net
Subject: Re: [ARC5] bc-950 vhf TX

> i have the BC-950A-121 vhf TX  need the Crystal for (145.600 & 144.900)
> the BC has 2 slot for the crystal holder make A&B only (B 122-156 MC
> 6777.777-8111.111) the 950 use the DC-31 type Crystal  i hvnt had
> time to see if the 950 was converted to a T-23 also any one have the
> manual for the BC-950 or T-23  thanks for any help  Dennis

If it still has a BC-950-A name plate it has not been converted.  Also, it's
damned hard to miss the 815 modulator tube up front that only the BC-950-A
has.

The BC-950-A transmitter uses the DC-30 crystal with thicker pins.  The
DC-31  crystal holder is used in the BC-942-A receiver.  The DC-30 was
replaced by the CR-1A/A, so that is what you need.  Unfortunately, you will
NOT find any crystal for 145.6 MHz because the closest standard aircraft
frequency of that era was 145.62 MHz using a 8090 kHz CR-1A/A.  However,
144.9 MHz was a standard aircraft frequency using a 8050 kHz CR-1A/A, so it
is possible you'll be able to find one of those.

Channel A is for 100 to 124 MHz operation.
Channel B is for 122 to 146 MHz operation.
Channel C is for 122 to 146 MHz operation.
Channel D is for 132 to 156 MHz operation.

Your two frequencies could use any of channels B, C, or D.

AFAIK, there are no known surviving manuals for the VHF SCR-274-N.  It was
never accepted for regular deployment.  The manual covering the T-23/ARC-5
may be downloaded here:

 http://www.radionerds.com/index.php/AN~ARC-5

You'll want AN 08-10-195 and its schematics.  BUT...as Dave Stinson and I
pointed out there are many subtle and significant differences between the
T-23 and the BC-950-A, especially in modulation and power connector wiring.
Dave is THE expert on those differences.

A surviving BC-950-A is sort of rare, especially compared to the much more
common T-23.  It would be a shame to ham-hack one that hasn't already been
violated, especially just for $hits and giggles like most such projects turn
in to.

Mike / KK5F
______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html