[ARC5] Why is the ARC-5 Tx rack so hard to find?

[Mike Morrow]

Robert wrote:

> A bit of trivia, apropos of nothing in particular, but some combined
> installations that include AN/ARC-5 did actually use a pair of PL-153.
> Just not between the modulator and control box.

It almost sounds like you describe the single-seat fighter installation, typically:

R-4A/ARR-2 Homing Receiver
R-26/ARC-5 HF Receiver, locked tuning
R-28/ARC-5 VHF Receiver, four-channel
T-20/ARC-5 HF Transmitter
T-23/ARC-5 VHF Transmitter
MD-7/ARC-5 Modulator
RE-2/ARC-5 Antenna Relay
C-30A/ARC-5 Transmitter Control Box, including VHF receiver channel selection.
C-38/ARC-5 Receiver Control Box, including Homing, but minus VHF channel
           selection.
MT-65/ARC-5 Three Receiver Rack.
MT-71/ARC-5 Two Transmitter Rack.

In this system:

A.R.C. 9121 (PL-153-A, 18-pin) connects to the C-38.  The wiring harness splits to three other connectors 9125,
  A.R.C. 9125 (PL-152-A, 8-pin) three required, connected to
         MT-65, R-26 position
         MT-65, R-28 position
         R-4A front panel

A.R.C. 9122 (PL-154-A, 12-pin) connects to C-30A.  The wiring harness splits to other connectors 9123 and 9821,
  A.R.C. 9123 (PL-151-A, 6-pin) R-28 front panel, channel select.
  A.R.C. 9821 (no PL number, 8-pin) T-23 front panel, channel select.

So, this system uses one 18-pin PL-153-A equivalent AND one 12-pin PL-154-A equivalent, neither anywhere near where the SCR-274-N uses them.

The above set is the version on AN/ARC-5 that I have assembled.  Most command set fans seem to believe that a typical AN/ARC-5 three-receiver, two-transmitter installation was like the ARA/ATA or SCR-274-N with upgraded components.  But that would have been very unusual.  The upgrade was far more profound.  The system described above provided VHF ZB-homing, one channel of HF comms, and four channels of VHF comms from its three receivers and two transmitters.  Very impressive for the era, IMHO.

Mike / KK5F