Continuous 1kHz tone from RRC-1258 MkII control heard on K3/0 Mini

[K6PO]

I have a K3/0 Mini with a RRC-1258 MkII at my control site. I use the Elecraft "octopus" cabling between the K3/0 and the RRC.

I am hearing a continuous 1kHz tone from the speaker in the K3/0. On an oscilloscope, looking at the SPKRS output of the K3/0, it appears as a noisy 1000 Hz triangle wave.

It is present and constant no matter the AF or RF gain settings on the K3/0. Changing keyer sidetone settings on the RRC has no effect. Disconnecting the AUX/MIC jack, or the I/O jack, or the USB jack, or the ethernet jack from the RRC have no effect. Unplugging the SP jack from the RRC does not stop it, and in fact makes it slightly louder (!). Unplugging the TTL jack stops the tone, as does disconnecting power from the RRC.

Anyone seen this, and knows what to do about it? Any help gratefully accepted.

73, Paul K6PO

[W1UE]

Paul, I've had that happen in the past.  It seemed to be produced by the proximity of the audio cables to the radio control cables.

I've had problems with the Spkr Out of the RR unit.  Try pulling the plug out slightly-if I do so I get increased audio and improved S/N
ratio on the audio.  If I push the plug in all the way audio is cut and S/N rises.

Dennis W1UE