[MRCA] C-24 LOCAL CONTROL UNIT

[Mike Morrow]

There are three different local control adapters that will work in these receivers interchangeably:

CBY-23154, made for very rare RAT, RAT-1, and RAV receivers.
FT-260-A, made for SCR-274-N receivers.
C-24/ARC-5, made for AN/ARC-5 receivers.

There were no local control adapters procured with the ARA receivers, but if there had been it would be the CBY-23154.

All have a 50 kohm linerar pot for RF gain plus a CW-OFF-MCW rotary switch.  No AF phone jack is provided.  In fact, the AN/ARC-5 receivers have no connection on J-1 to the AF output transformer secondary.  (The ARA and SCR-274-N receivers have such a connection.  The R-23* and R-24/ARC-5 do have a specially-filtered for 90 and 150 Hz low-level AF signal from the 12A6 cathode circuit intended to supply localizer signal AF to the Air-Track ILS AN/ARN-9 through the MX-19/ARC-5 receiver ILS audio adapter panel.  The Air-Track ILS and AN/ARN-9 were abandoned by the USN in 1944 in favor of the far superior USAAF SCS-51 ILS, so you won't find much mention of that ILS.)

These local control adapters are ALL very difficult to find easily, with the FT-260-A being the most common version and the CBY-23154 the rarest.  Because of that, and because soldering a home-made substitute to the pins of receiver front connector J-1 ALWAYS irreparably damages J-1, a useful alternative is to built the equivalent circuits on an external panel connected to the rear connector J-3.

Mike / KK5F

-----Original Message-----
From: ROBERT FORTE <rvforte at gmail.com>
Sent: Jul 11, 2021 3:46 PM

HI GUYS, IF ANYONE HAS A C-24 LOCAL CONTROL UNIT FOR THE ARC-5 RADIOS PLEASE CONTACT ME. THANKS, ROB FORTE K2RGM