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
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