[Milsurplus] Questions? (more)

[W7QHO at aol.com]

Rick,

The early BC-312 and 342 receivers (no suffix, A and C models) had TWO of the 
connectors in question mounted on the front panel.   One was for the signal 
antenna (SIG ANT) and was retained in the same configuration and position on 
all subsequent 312/342 models. The other connector was for an ignition noise 
suppression network included in these early models and was labeled "NOISE ANT."
The noise canceling circuit was not retained in all models later than "C" as 
mentioned above and the connector was replaced with the familiar spring-push 
terminal which was connected in parallel with the SIG ANT connector and labeled 
ALT SIG ANT.   

The only reference I can find of anything being connected to the SIG ANT 
fixture is in the early SCR-193 A, B and C models.   In all three systems use of 
the FT-177-A right angle adapter is called for at both the receiver and 
transmitter ends and special interconnecting cords are specified, CD-261 for the 
193-A and C, and CD-262 for the 193-B.   

The later SCR-193 D & E models, on the other hand, show the receiver antenna 
connection being made to the ALT SIG ANT terminal and call for the use of wire 
W-128 for this purpose.   Ditto the antenna connection to the BC-312 in the 
SCR-245.   Based on this, I would surmise that the SIG ANT connector was not 
used in the SCR-299/399/499 systems, rather, the connections from the separate 
receiving antennas were brought in to the ALT SIG ANT terminal with W-128 wire 
or something equivalent.    

These unique fixtures appear to have been intended to accommodate some early 
type of coaxial RF cable used only in early systems.   Their retention in 
later receiver models is puzzling but may have been done to insure compatibility 
with older setups.   Another example of this is the availability of 12 vdc on 
the 3-way speaker jacks in the BC-312 to excite the field coils in the early 
speakers.   This feature was retained in all 312 models except the 24 volt "HX" 
and "NX" versions.

Do you have an example of the mating connector?   I can send you a picture if 
you would like.


Dennis D. W7QHO
Glendale, CA