[RFI] Finally located my RFI

[Dave (NK7Z)]

Howdy,

I have been chasing an RFI source that comes on and goes off on about a 
7 minute cycle for 3 months now, I have suspected it was HVAC related by 
it's behavior... and timings of changes I have seen...  Runs different 
at night, if an abrupt temp change occurs, a corresponding change in the 
cycle times, and lengths...

It consists of broadband noise from 17 MHz, to 29 MHz.  Worst at 24 MHz, 
not bad on 28 and 17 Mhz.  It did not do this when it was installed, it 
has recently changed...  He has had a lot of electrical work of late as 
well.

Anyway, my neighbor had his vents cleaned, and let me know in advance... 
  I started my S Meter logger last night, and ran it all night, and this 
morning...  Seven Minutes after the HVAC people arrived, the RFI 
ended...  I asked the tech about this, and he said he had just shut off 
the units...  BINGO!!!!!!!!!!!!!!!!  I asked him to text me as he 
brought up each unit...  He did, and I now know what unit it is causing 
the issue...

He also indicated they were having issues with the Mitsubishi inverter 
unit getting into people's LED lights, and cycling them...  Sounds like 
it is really noisy on the power grid...

Does anyone have any experience or a contact at Mitsubishi, or any 
suggestions on mitigation of this?  I may start by having the HVAC 
people install some ferrites on the power to the inverter, at the 
inverter...  But I want to contact Mitsubishi as well and see if they 
have an RFI kit...

The unit model is SUZ-KA12NA, Service Ref: SUZ-KA12NAR1.TH

-- 
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources