[Milsurplus] Bendix TA-12

Michael Hanz aaf-radio-1 at aafradio.org
Fri Aug 16 16:18:26 EDT 2019


Just to add to Mike's excellent tabulation, here is the TA-12D coverage (from the Bendix equipment manual for the Commonwealth version of the Douglas A-20 Havoc called the_Boston_.)

Ch. 1 - 1200 to  1540 kHz
Ch. 2 - 2000 to  3400 kHz
Ch, 3 - 3000 to  4800 kHz
Ch. 4 - 4370 to  7000 kHz

  - Mike  KC4TOS



On 8/16/2019 3:03 PM, Mike Morrow wrote:
>> Can anyone tell me the frequency coverage of the Bendix TA-12G
>> transmitter? I’m trying to make some equipment ID cards for a
>> radio display and can’t find my TA-12 manual. Note this is for
>> the G model, not the more common B or C.
> It's not likely that your TA-12 manual would have helped.  The TA-12G is the last and most refined of the TA-12 series, with some improvements in the PA output tuning capacitor configurations and a small "wave meter" neon indicator to help assure correct MF channel 1 tuning.  The TA-12G is built by Northern Electric Company, and it should have come with a heavy paper calibration graph stowed under the transmitter case.
>
> The first three TA-12G channels have the same frequency range as the TA-12B.  The fourth channel is as shown below.
>
> Ch. 1 -  300 to   600 kHz  TA-12B  TA-12C  TA-12G
> Ch. 2 - 3000 to  4800 kHz  TA-12B  TA-12C  TA-12G
> Ch, 3 - 4000 to  6400 kHz  TA-12B          TA-12G
>          4800 to  7680 kHz          TA-12C
> Ch. 4 - 4370 to  7000 kHz  TA-12B
>          5750 to  9000 kHz                  TA-12G
>          7680 to 12000 kHz          TA-12C
>
> Frequency coverage overlap of the three remotely-selected HF channels allows more flexibility for using channel frequencies relatively close to each other.  The TA-12B has the best channel overlap but coverage stops at 7000 kHz,  The TA-12G has less channel overlap but coverage stops at 9000 kHz.  The TA-12C has NO channel overlap, but coverage stops at 12000 kHz.  Unfortunately, that was not especially useful in the WWII era, nor was it supported by the associated RA-10-series receiver whose coverage ends at 10000 kHz.
>
> The RA-10DB receiver's coverage is;
>
> Band 1 -   150 to   400 kHz
> Band 2 -   400 to  1100 kHz
> Band 3 -  2000 to  5000 kHz
> Band 4 -  5000 to 10000 kHz
>
> I have always admired this particular Bendix system.  I have:
>
> RA-10DB LF/MF/HF manually-tuned receiver with dynamotor and
>          with MR-11D loop relay unit
> MR-9B   Receiver control box
> MN-20E  DF Loop
> MN-52B  DF Loop control box
>
> TA-12B  MF/HF four-channel transmitter
> MT-53B  MF tank coil
> MT-51C  Transmittee control box
> MP-28BA Modulator/dynamotor
>
> Plus other ancillary items.
>
> It seems a pretty good compact 1940-era system that provided a four-channel HF communications set with some LF/MF DF capability.
>
> Mike / KK5F
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-- 
Michael Hanz - KC4TOS

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