[SADXA] 3rd harmonics of 160m sigs

[Jim KF7E]

     I stumbled across some CW signals on the 5400-5600 KHz band 
tonight, from stations working the 160m contest.

     At first I thought my TS-590 was doing something odd, but I hooked 
up a spare rig, and heard exactly the same harmonics from the same 
callsigns.

     In all cases I could hear the stations on both their 160m freq, as 
well as the harmonic, and on both my receivers.

     I have heard at least three stations as they QSY up and down 160m.

     Has anyone else noticed this?

     Hastily tuned amps?  Diode rectification?  Odd.....


KF7E