[TowerTalk] Harmonics rectification in bearings or Pro.Sis. Tel rotors?

[SM0HRP Kari Gustafsson]

Hi, 

I have discovered what it seems like rectification in my HD Alu Tower where
on the top there is antenna ball bearing thrust (SKF) below a 61D Prosistel
rotor. I used various techniques to pin poin to the tower.

The harmonics is growl sounding on 20 m (TX on 40 m) and is some -120 dB
below the fundamental (40 m) after double low- and high as filters (giving
some 100 dB of combined out of band suppression) in TX and RX chain. 

I have read that some have encountered harmonics rectification in thrust
bearings. Anyone has any experience from ball bearings and rectification? Or
rectification in Prosistel rotors (in the potentiometer?). 

Being a physicist I wonder how the mechanism is with this kind of
rectification in bearings and grease which I assume is isolating. Or? 

I am close to getting a skylift and do the shortening of the bearing with a
jumper and see if it helps bit it is winter her. Brr.cold.

73s Kari SM0HRP