[MRCA] Looking for TA-12C

[Mike Morrow]

I wrote:

>The TA-12C provides LF/MF, and MF/HF coverage to 12 MHz in four *non-overlapping*
>bands.  In comparison, the TA-12B provides LF/MF and HF coverage to 7.7 MHz in
>four bands with wide overlap.  That allows the TA-12B to be tuned to more preset
>HF channels in the useful 4 to 7 MHz range than the TA-12C can accomodate.  Plus,
>RA-10DB coverage ends at 10 MHz, so TA-12C coverage of 10 and 12 MHz would have
>been pretty useless.

I should proof-read more before posting.  TA-12B coverage ends at 7.0, not 7.7 MHz.

To summarize, here is the coverage in kHz of these Bendix units:

                TA-12B           TA-12C
Channel 1    300 to   600     300 to   600
Channel 2   3000 to  4800    3000 to  4800
Channel 3   4000 to  6400    4800 to  7680
Channel 4   4300 to  7000    7680 to 12000

                RA-10DB
Band 1       150 to   400
Band 2       400 to  1100
Band 3      2000 to  5000
Band 4      5000 to 10000

The RA-10DA is identical to the RA-10DB, except that it does not come from the factory with circuitry to support DF loop antenna connection for bands 1 and 2.

Since the most commonly used aircraft frequencies during the early 1940s were below 7000 kHz, TA-12B frequency coverage (with large overlaps on channels 2 through 4) would appear to have been more generally useful than that of the TA-12C.

Mike / KK5F