[ARC5] bc-950 vhf TX

[Mike Morrow]

> 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