[RFI] Broadcast station RFI Mixing - RESOLVED

john at kk9a.com john at kk9a.com
Thu May 29 07:23:44 EDT 2014

I had a very similar situation when I had my 160' tower loaded with ring
rotators near Chicago. It had a homebrew 80m rotating dipole on top and I
heard a mix of local broadcast stations on this band.  40m was fine. I
never found a solution except for using a separate RX antenna. I assume
that my rings are grounded though the motor and from touching at least one
of the side bearings however I never verified this and there are many
variations of TIC rings. This would have definitely been worth trying!

John KK9A

To:	 "rfi at contesting.com" <rfi at contesting.com>
Subject:	 Re: [RFI] Broadcast station RFI Mixing - RESOLVED
From:	 Rich Hallman - N7TR <rich at n7tr.com>
Date:	 Mon, 26 May 2014 17:52:43 +0000

After several months of looking for the broadcast mix I finally purchased
a HF
Direction Finder from http://www.nationalrf.com/type_hfdf_vector.htm.  This
really helped me pinpoint where the noise was generating from.  What I found
was with the HFDF unit and listening to the loud mix on 3.900, I tracked it
down to the new HDX689 tower I installed last year.  I just have a single M2
rotatable dipole up and figured it has to do with that antenna.  After
completely disconnecting the antenna and grounding parts of the elements, it
didn't help.  I then began moving the M2 15M6 that is mounted on a new model
TIC Ring and noticed the noise would get real bad when I rotated the ring.  I
then grounded the rotating platform on the Tic-Ring to the tower and the
went away!

I reinstalled the 80 meter rotating coax and all the cabling while keeping
rotating ring part of the TIC-Ring grounded, and I have no problems.   I
removed the ground to the tic-ring rotating platform and the noise came back.

Next question....Anyone have a Tic-Ring that they have had this problem with?
Im just glad at this point I found my mixing issues.


-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Rich Hallman -
Sent: Saturday, April 19, 2014 6:13 PM
To: rfi at contesting.com
Subject: [RFI] Broadcast station RFI Mixing

Over the past year I have been hearing a local broadcast station on 80 and 40
meters.  80 meters is the worse.  Filters will not help, and sounds like
is something rectifying.  I think I may have a problem on the power pole
it seems to go away for a day or so after it rains.  Also...I have not
eliminated that there may be a problem at the broadcast site.  The station is
KKOH and is about 10 miles from me...but line of site.

I did a YouTube video of what I am hearing...and for the most part I can hear
the carrier every 10 khz...so places like 3900 is real bad.  With the
intermittent connection as it sounds like...it messes up the entire 80 and 40
meter band.  Sounds like a bad connection in my antenna...but I have already
confirmed my antennas are fine and I confirmed I can also hear the mixing
on a
mobile 80 meter whip in the truck as well as other antennas.  On 40 its lower
signal...but also can be heard every 10 khz or so and the mixing is very
intermittent / scratchy.  Seems like its also more intermittent with wind.

Here is the video...   http://youtu.be/rZ8gXRKGkxE

I just emailed my power company the video as well.  Will get the KKOH station
engineer to listen as well to make sure they don't have an issue with an
insulator or ground on their tower.

Any other thoughts?

Rich N7TR
Telnet: dxc.n7tr.com N7TR DXCluster

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