[SADXA] RFI

[Wes]

I haven't been too active lately, so I can't pinpoint when this started but I 
discovered it on Field Day when I was plagued with an intermittent noise that 
made me give up.  Trico has been quite good about working these issues, but the 
intermittent nature didn't bode well for it happening when they were looking.  
So I did some sleuthing of my own.  My tribander is about 120 feet from the 
house and my power line is to the west of it.  The house is NE of the tower.  
The noise actually went down when pointed west but peaked when pointed at the 
house.  I could hear it everywhere from 160 to 6 meters on my Sony ICF-SW7600, 
even inside the house when it was on.  The problem was it was off more than on.

I had a previous issue with my Internet system causing a problem when the 
Ethernet cable hooked to the rooftop Wi-Max receiver wasn't plugged in 
completely by the service guy after an antenna change.  So I went up on the roof 
(it was 106 deg) with the receiver to sniff around.  Of course the noise was 
gone by then.

I have a 13-year old, rooftop packaged Trane heat pump model WCZ060F100BD near 
the Wi-Max system and while I was on the roof, it turned off and the noise 
erupted.  The heat pump was the source, but not while running.  I could hear an 
audible buzzing sound inside the box.  I pulled the fuses and all was quiet.  
Plug them back in, noise, both audible and RF resumes.  Heat pump turns on to 
cool and noise is gone.

Investigating inside I determined that the potential relay was chattering when 
in standby.  When cooling it pulls in, disconnects the starting capacitor and 
the unit runs normally.  No one but a ham would ever know there was a problem.  
Looking at a generic schematic 
(https://www.achrnews.com/articles/93735-potential-starting-relays) I don't see 
how this can happen.  Clearly, there is more to this.

Unfortunately, Trane (American Standard) guards their schematics like gold in 
Ft. Knox and I've been unable to find one for further troubleshooting.  I'm open 
to any and all ideas.  Links to a complete schematic would really be appreciated.

Wes  N7WS