Somehow the connector shorted internally, have seen them go open before but rarely short. Did cut back the other end of the cable, RG-174 where they had soldered around the cable to make a ground pigtail, but that was all good so figure it had something to do with the crimped-on connector or its heat wrap.
I have seen several cases where the molded covering around pre-formed connectors on coax have expanded over the years and pulled the internal connection apart and tend to stay away from the pretty preformed cables just for that reason.

Ray F/KA3EKH



From: [email protected] <[email protected]> on behalf of mstangelo--- via Milsurplus <[email protected]>
Sent: Friday, August 14, 2026 11:53 AM
To: [email protected] <[email protected]>; [email protected] <[email protected]>
Subject: Re: [Milsurplus] [MRCA] Mackay MSR-8000

Ray,
 
Good detective work. How did the SMA connection fail, an opening between the coax and connector?
 
Mike N2MS 
On 08/14/2026 11:30 AM EDT Ray Fantini via MRCA <[email protected]> wrote:
 
 
Resolution of the MSR-8000, turns out one of the two SMA connectors and cables that bring audio into the 1A1A3 card was internally shorted. It's the connector for the high-level carbon microphone feed that goes to 1U(B) directly. That pulled the audio down at the junction that feeds pin 3 of U1(B)  but because the 1 kHz signal for CW is injected past U1 that's why CW was not affected.  Have seen SMA connection fail before on other radios. 
Sorry, but still no love for Mackay products.
 
Ray F/KA3EKH
 
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