Ok guys, time for an update on this. Tried a bunch of things with the HV supplies. Connected the capacitor stack from my 813 amp and added a big 10h choke to the 1250v supply, added a 5H choke and a caps to the 400v supply to form clc filters on both supplies, no improvements.. Still heard the buzz on the monitor receiver in the shack. Got tired of messing around and tuned up on the cw part on 80m and got nice reports, except for some chirp
Listening around on saturday I heard some AM stations, called them up the '13, and none of them had any complaints about rectifier or mains buzz of any sorts. A mains filter is ordered, and if it doesnt change anything I'll let it be as it is.