[Milsurplus] General Radio 1931-A Modulation Monitor

[Ray Fantini]

They were often paired with the old RCA or Gates transmitters that were used for carrier current AM systems at military bases back in the fifties and sixties. Although you may think carrier current systems are small was not unusual to see transmitters sometimes sized up to 1 Kw that would be located at the base power plant.
Is your 1931 gray or black front panel? The black are the oldest. I have a 1931 paired with my RCA BTA1-MX transmitter for 160 AM.


Ray F

-----Original Message-----
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Brian Harris via Milsurplus
Sent: Monday, May 05, 2014 10:19 PM
To: Boat Anchors; Military Surplus
Subject: [Milsurplus] General Radio 1931-A Modulation Monitor

I recently acquired my second General Radio 1931-A Modulation Monitor.  This one is a much later serial number (2688) than my first one (370).  On the front panel of this second is stenciled the following:

AF33-604-16827
7CAC-575975

First question:  Can anyone shed light on the nature of this stencil?  Might the AF mean Air Force?

Second question:  These units required a coil specific to a frequency range.  I have two coils, both of which cover .5-8 MHz in four ranges.  These are the most common coils as these units were most often used with AM Broadcast transmitters.  I would like to obtain one or two of the higher frequency coil, which I recall covers 8 - 30 MHz.  If there is an outside chance that you might have one or two of these available please let me know.  Of course I can fashion some myself but that is something I'd like to avoid.

Thank  you,
 
Brian Harris, WA5UEK 
cell 214-763-5977 
email cosmophone at yahoo.com