[Milsurplus] Radio in USMC Gun Motor Carriage 75mm M3

[WA5CAB at cs.com]

Group,

Original interphone amp was CMX-50128.  Only minor differences between it and 
the A.  Dynamotor used is one of those that look like a DM-32 or CBY-21531 
(or equivalent from RAT or RAV) until you look more closely.  Has same connector 
but the base plate is two-level, not straight as on the aircraft ones.

There were several Remote Control Boxes besides the 23270.  The 23355 that Ed 
mentioned looks just like the 23270 except that it has a INTERPHONE-RADIO 
switch and an additional pair of mic and phone jacks.  23366 is same but without 
the loudspeaker.  23398 is smaller, green, and apparently intended for use at 
the far end of twisted-pair field wire as it has a pair of binding posts 
labeled L1 and L2 and holds two BA-30's.  Never found any paper on it.  23429 is 
about the same size as a BC-606 but has an open flanged back for mounting to a 
pre-existing cut-out in a junction box or in the hull of an LVT-(*).  It has 
two pair of sealed mic and phone jacks, three switches and a volume control pot. 
 It was also used in the M3 Medium Tank (General Grant) strangely enough.  
And I suspect that it would have been the remote control box used in the MZ but 
can't prove it.

The short cables also came in 2' to 2.5' lengths, for use with AN/MRC-6(*).  
Interestingly enough, those dating from the Korean War were built up using 
WM-46/U Interphone Cable.

I have manuals on the 50128 and 50128A.  But in typical TM fashion, they are 
mute when it comes to exactly how the Interphone Amps were actually used.

In a message dated 12/1/2005 9:22:17 PM Central Standard Time, 
ezeran at ezeran.cnc.net writes: 
> >There is an amp
> >used with the TCS in such installations.
> 
> Ed: Interesting info.  What amp would that have been?
> 
> Perry
> 
> Perry, Paul, and the group,
> 
>     The amp nomenclature is CMX-50128A, interphone amplifier, made by 
> Magnavox.
> I've had a couple of them and Larry Godek W0OGH had one also, I believe, as
> well as the dynamotor. The installations also had a TCS control box
> different from the normal one and I think Robert Downs knows about them.
> The one manual I can find was water damaged in storage by a plumbing problem
> but I can still scan the info if anybody wants it. Another aside.....Those
> TCS cables that are about 10" long and seem too short ( the esteemed Mr.
> Bill Donzelli had some) for use are in the alligator photo.
> 
>     The amp uses two P/P 12A6s
>     Control box is -23355 rather than -23270. The -23355 lets the crew use 
> the
> installation as ICS without keying the TX.
> 
> EdZ
> 

Robert Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at houston.rr.com> (Backup email)