[Milsurplus] Bendix TA-12C, Need Info

[Mike Morrow]

Jim wrote:

>A Bendix TA-12C followed me home from an estate sale this past 
>weekend.  It looks like was sitting a garage for many 
>years.  Unfortunately there was no power supply, but I should have 
>some suitable transformers for a home brew supply:

The dynamotor power supply and modulator unit is the MP-28BA.
They are fairly rare, but not as rare as the MT-51C control box.

>The front panel seems to be secured to the case with suitcase 
>fasteners.  However, after loosening them, the nothing budges.  Some 
>gentle tapping on the edge with a screwdriver and hammer in the 
>deceased's garage didn't help.  Should any screws be removed?

As I recall, you also have to drop a hinged plate on the left
side to allow the power connector to pass out of the case.  But
that wouldn't cause your "stuck in place" (by corrosion?) effect.

>Any suggestions regarding a manual or even a schematic?

An almost complete Bendix manual for the TA-12B and C, including
frequency calibration charts, is in pdf format at:

http://www.vmarsmanuals.co.uk/archive/1139_TA12B_C_manual.pdf

Unfortunately, it is missing a couple of figures, including 
Figure 23 which is the schematic for the MP-28BA.  Fortunately,
Mike Hanz's cited documentation page has the schematic for the
MP-28B.  Robert/WA5CAB's manual (which I have) for the TA-12C
is complete and the best of the lot.  For some reason, it's
very hard to find original Bendix maintenance manuals for the
TA-12 (Bendix IB 393).

Other items needed for a TA-12B or C installation besides the 
transmitter:

MP-28BA Dynamotor/Modulator
MT-51C  Transmitter Remote Control Box
MT-31C  Plug-in Tuning Meter
MT-53B  MF Tank Coil (for channel 1, 300 to 600 kc)

The associated receiver system consisted of:

RA-10DB Receiver [or some other RA-10** variety]
        (150 to 1100 kc, 2000 to 10000 kc)
        with MR-11D Loop Relay Unit
MR-9B   Receiver Remote Control Box
MN-20E  Receiver LF/MF RDF Loop
MN-52B  Receiver RDF Loop Control Box

The RA-10DB and the MR-9B are usually hard to find.  

I've got everything needed for a complete RA-10DB/TA-12B
system except for the required connectors.

I like the capabilities of this combo for providing 
multichannel MF/HF transmission, reception coverage of
the most important frequency ranges, and limited RDF
capability.  The TA-12B has a fair amount of overlap
on its three HF channels, but coverage stops at 7000 kc.
The TA-12C has much less channel overlap, but coverage
goes up to 12000 kc.  Unfortunately, the receiver only
goes to 10000 kc.  I think the overlap on the TA-12B
allowed for better coverage of HF channels below 7000 kc,
where most of the important aircraft frequencies were.

Mike / KK5F