[MRCA] [MMRCG] Help with an ARC-4

[Robert Downs]

Paul,

 

I have next to no hands-on experience with the AN/ARC-4 or WECo 233.  And although in my TM collection I have two or three of the Operator’s Manuals, I don’t appear to have ever come across a Maintenance Manual.  However, USMC used it as a portable and vehicular VHF set called the MAH which I do have the NAVSHIPS manual on.  Studying it briefly I am reminded that the radio is actually two receivers in one, one called Plane-To-Plane or P-P and one called Plane-To-Ground or P-G.  There is in the system a control box that selects either or both.  Try jumpering pin 18 to 19 on the large rectangular connector on the back of the radio.

 

I do have a reprint available of the MAH manual.

 

Robert Downs

 

From: MMRCG at groups.io [mailto:MMRCG at groups.io] On Behalf Of Paul Sokoloff WA3GFZ
Sent: Wednesday, April 8, 2020 19:32
To: mrca; MMRCG at groups.io
Subject: [MMRCG] Help with an ARC-4

 

An amazing thing happened.  I powered it up and it received.  Just having issues with the noise gate (squelch) circuit.  It seems to shut the audio down when the signal is too low (which is normal), but also shuts the audio down as the signal level increases.  I spent the afternoon replacing parts in the circuit and the tube but no change.  Looking at the 10 MHz IF on the plate of the last IF amplifier looks fine.  Does anyone have experience with this radio?  I know it's kind of and oddball one.  I'd like to get the noise gate working or disable it. 

 

Thanks,  Paul  WA3GFZ 

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