[RFI] 160 Meter RFI

Ray rayk9rs at gmail.com
Thu Dec 6 16:41:30 EST 2018

Thanks Dave and everyone else who responded.
To answer your questions:
It does change sounds right at the end and sounds like a few tones before
it disappears.
It seems to be on every 20 to 45 minutes and stays for 5 to 10 minutes. I
kept data all last weekend and can't see any more of a pattern than that.
It is always the same as far as I can tell
It does not show up on any other bands that I can tell but I don't think
it's confined to exactly 160 meters. I will try to be more definitive on
that when I look tonight.
I am fairly certain it is not in my house. I have pretty directive RX
antennas on 160 that are pretty well decoupled and 200 feet from my house
and it is definitely strongest to the North East of my house. There are 10
or 15 houses in that general direction although I am not sure yet if that
is the area or it is further. One of those has a solar system (still not
sure why solar cells on your roof are OK but antennas are not).
I am in a no antenna HOA area but manage to put up some impressive stealth
antennas in the woods. For the recent ARRL 160 contest I managed 1228
contacts and 47 countries but could have done much better without this
I will work on hunting it down with a loop but if anyone has any ideas of
specific equipment I think it would help in my discussion with the
Thanks again & 73,
Ray K9RS

-----Original Message-----
> From: RFI <rfi-bounces at contesting.com<mailto:rfi-bounces at contesting.com>>
> On Behalf Of Dave Cole (NK7Z)
> Sent: Wednesday, December 5, 2018 5:29 PM
> To: rfi at contesting.com<mailto:rfi at contesting.com>
> Subject: Re: [RFI] 160 Meter RFI
> Hi Ray,
> Trying to guess the source from looking at captures can be tough...
> That said, here are a few questions:
> 1.  Does it ever change sound?
> 2.  Does it run on a schedule?
> 3.  It is always the same?
> 4.  Is it just on 160?
> If it runs on s schedule, kill your house power at one of the run times
> for it to test if it is in your home...
> It looks like a SMPS.  Once you get proof it is not in your home, buy or
> better yet, build a loop.
> Look over Jim's paper, it does make a difference for the better, if you
> follow his steps for quieting down your RF environment.
> Take a look at my page at:
> https://www.nk7z.net/sdr-rfi-survey-p1/
> That is part I of a two part series on getting to know your RFI
> environment using an SDR.  There are several other links on the right
> dealing with RFI as well...
> 73s and thanks,
> Dave (NK7Z/NNR0DC)
> https://www.nk7z.net
> ARRL Technical Specialist
> ARRL Volunteer Examiner
> ARRL OOC for Oregon
> On 12/5/18 9:10 AM, Ray wrote:
>  I have this 160 Meter RFI :  https://youtu.be/QI08sE2FS40 It shows up
>  once or twice an hour for 5 to 10 minutes. Any ideas what it is?
>  Thanks,
>  Ray K9RS

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