[Boatanchors] General Radio 1931-A Modulation Monitor

[rbethman]

Just a little information regarding Modulation Monitors.

Did you know that ALL are Northern Friends, Canadian Amateurs, were once 
required to have on at their station to run AM?

I picked up one from the North made by Simpson.

Bob - N0DGN

On 5/5/2014 10:18 PM, Brian Harris via Boatanchors wrote:
> 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