How does the audio sound on these spurs? Is it "clean" sounding? Or distorted? Also does this QRM remain constant? or does its signal strength tend to "jump around" a lot?
It's not clean sounding. It's very muffled on the random spurs. On the harmonics (like 4710 KHz) its a little cleaner sounding but still quite muffled.
Chris: thanks for the information about the PAR filter. I'll keep that as an option. I'd really like this to just stop, however. I have never had this problem... never ANY mediumwave products, in the 7 years I have been at this location. And then BOOM, one day in January it starts.
Update: I took a portable (Tecsun PL-380) with me to a spot about 3 miles from my shack. The same stuff is notable there. Very loud odd harmonics of 1570 KHz (e.g. 4710 KHz) and spurs and images everywhere else. Granted not quite as strong as on my shack rigs, but those are probably much more sensitive and have larger antennas. I know, now, that it's not a problem specific to my shack. Still, a discouraging situation. Ideas on how to proceed?