[ARC5] ATA Transmitter Control Box

[Mike Morrow]

Robert wrote:

>Well, OK.  But I discounted the C-38 (which only controls two lock-tuned 
>MF/HF receivers) for that reason and that the original question was prompted by 
>the 4-position switch on the ATA control box.  So to rephrase, AFAIK, there was 
>never a 4-receiver control box built that controlled four MF/HF Command Set 
>receivers complete with tuning dials and cranks.

I knew what you meant, Robert.  I was just having some fun.

The subject of command set control boxes is interesting to me.  Years ago before
some of the knowledge of fellow list members rubbed off on me, I did't know how
different the AN/ARC-5 controls were, compared to the ARA/ATA and SCR-274-N units.

As you said, there is no receiver control box in the AN/ARC-5 system that controls
four LF/MF/HF tunable receivers.  For that matter, there isn't one that controls
three such receivers, such as the earlier CBY/CTT-23251 or BC-450-A units do.  The
only AN/ARC-5 box capable of controlling two MF/HF tunable receivers is the odd
and scarce C-43/ARC-5 that controls two such receivers, plus an R-28 VHF receiver
(audio).  Multiple tunable LF/MF/HF receivers normally required multiple single-
receiver C-26/ARC-5 control boxes or C-125/ARC-5 control panels.

The other thing that is interesting to me is that while the ARA and SCR-274-N
single-receiver control boxes control frequency, RF sensitivity, mode, and power,
the similar C-26 box eliminated power control.  The C-125 panel further eliminated
mode control.  The extreme is the C-27/ARC-5 single lock-tuned receiver control
box which additionally eliminated frequency control.  The C-27 has only a gross
ON/OFF RF sensitivity control switch and a thumb-wheel variable RF potentiometer.
It all makes sense as part of the effort to eliminate superfluous radio controls
in the cockpit.  The ON/OFF switch on the C-27 and C-38 lock-tuned receiver
control boxes is sometimes mistaken for a power switch, but all it does in the
OFF position is insert a 100k-ohm resistor in the RF sensitivity control path.

73,
Mike / KK5F