[Milsurplus] "Command Set" vs. "Liaison Set"

[Mike Hanz]

Well, you are only scratching the surface, Jim.  It gets even more 
complex.  For example, the control boxes in the Enola Gay are all BC-366 
boxes.  However, they have decals on them that say "Modified to 
BC-1366".  Under the "command" label there is a small tag held on by two 
screws.  It says "VHF" on this plate.  In *addition*, "VHF" is 
*engraved* above the Liaison label, exactly like yours.  You can see one 
of these boxes if you scroll to the very bottom photo at 
http://aafradio.org/flightdeck/Peripherals-headsets.html

I'll give you my take on all this confusion, for what little it's worth, 
and that is that the arrival of VHF capability in USAAF aircraft created 
a problem from an audio source selection standpoint.  They had all these 
BC-366 jack boxes out there in thousands of planes, and some aircraft 
got VHF early, some didn't until long after their first introduction.  
AN 16-30-AIC2-2 for the AIC-2 replacement for the old BC-347 interphone 
amplifier series of RCs (RC-34, RC-35, RC-36, RC-51, etc.) contains the 
BC-1366 (and BC-1366M, which had a different pot value) and has this note:

"(3)  For the radio operator's jack box, wire the liaison radio set to 
the "LIAISON-VHF" terminals of the jack box (terminals 2, 6, and 8) and 
connect the audio output of the VHF radio set  to the spare call circuit 
(terminal 7).  Block out the letters "VHF" on the cover.

(4)  For all other jack box stations in the airplane, connect the VHF 
radio set to the spare call circuit (terminal 7).  Block out the word 
"LIAISON" on the cover."

 From the B-29 labeling, there was obviously some latitude for what was 
blocked out and who got what on their jack box, and a fair amount of 
modifying existing BC-366 jack boxes.

One puzzlement is that the "spare call circuit" is simply connected to 
the earphone jack, so it would presumably be heard anytime there was 
audio on that circuit..

I suspect that the confusion simply reflected the fog of war. :-)

73,
Mike

On 3/15/2012 4:07 PM, Jim Haynes wrote:
> And just to confuse the issue...
>
> The BC-366 jack boxes used in airplanes had a five-position rotary switch:
> COMP (compass) LIAISON COMMAND INTER (interphone) and CALL (call on the
> interphone).
>
> The later BC-1366 jack boxes had positions:
> COMP V.H.F._LIAISON COMMAND INTER CALL
>
> Now it seems that a VHF set would be used more like a command set, and
> doesn't have the long range liaison capability.  So does this marking
> imply that the liaison set was VHF, or that the switch position means
> "either VHF set or liaison set, depending on what is installed in the
> particular airplane"?