[RFI] advice wanted: finding the source of mixing products

[Jim Brown]

On 2/24/2020 1:03 PM, Matt NQ6N wrote:
> Thanks much for the tips, Jim.  Do you know if the wall warts can cause 
> mixing when they are not plugged into the wall or if the circuit breaker 
> is turned off?

They can cause mixing if connected to wires that can function as RX and 
TX antennas. And when operating, they produce noise which gets radiated 
and received by your antennas. SMPS are noise generators, which the 
major reason for a search out and destroy mission.

> In my testing the other day I did not see any difference in the 14.786 
> MHz mixing product when turning off all of the breakers in the breaker 
> box. Does that test eliminate any warts on those circuits as culprits 
> for the specific mixing that remains present at 14.786?

No, power is not required for them to cause mixing -- it's passive 
device in that regard.

> My next test will be to power down the entire house and transmit with 
> the KX2 on battery, connected directly to the antenna, and confirm that 
> the mixing product is still there (eliminating anything in the shack 
> itself).

As noted above, that is NOT a meaningful test.

73, Jim K9YC