Setting up a replacement VHF machine for one of the club’s sites, its nearly ready to deploy. But there is a issue I cant work out. The thing gives everyone a randomly timed raspberry!

its a MTR2000 with a Masters Communications RA-DR1X interface using a RPi4 running ASL3 asl3-3.7.1 using the SimpleUSB channel driver

Have a listen, first bit is 1000Hz test tone with berries, then without the test tone and still with berries, the whizzing sound is the fan from one of the service monitors

I have heard this on 2 other machines (Quantar and MASTR II) running older ASL versions and the USBRadio channel driver, at much lower levels and with less volume and fewer occurrences.

I had always attributed this to the DSP driver, but in this case it cant be that.

I do not believe I have any audio setting far out of whack, If I put 3Khz in I get 3Khz out

Here are the parameters

Device String is 1-1.2:1.0
Card is 1
Rx Level currently set to 500
Tx A Level currently set to 500
Tx B Level currently set to 500

this artifact only occurs on receiver audio and is sent out both local and out to the network, not on audio from other sources

This one has got me stumped, and everyone on air notices it right off.