[RFI] Noise located and FIXED

[Dave Hachadorian]

Hi Don,

The pole is 2.1 miles from my QTH.

When I tried unsuccessfully to use the flag in the end-game, it turned out that I was only about 100 yards from the offending pole. I wanted to remove the preamp, but didn’t have the correct connectors to bypass it, so I had to leave the preamp in and add the attenuator.  I didn’t think of using the flag at a higher HF frequency.  I’ll keep that in mind for next time.

Now that I have one success under my belt, it has given me hope and confidence that I can lower my noise floor even more!

Thanks for your work in designing the flag, and for all of your postings on the reflector!

73

Dave Hachadorian, K6LL
Yuma, AZ

From: Don Kirk 
Sent: Saturday, June 19, 2021 1:53 PM
To: Dave Hachadorian 
Cc: reflector RFI 
Subject: Re: [RFI] Noise located and FIXED

Hi Dave,

Thanks for sharing and great story.  How far from your QTH was the bad pole and how close to the pole when you had to switch to VHF?

The more you use the portable flag the more comfortable you will become with how it works.  You probably could have moved up to 14 or 21 MHz as you approached the pole using the portable flag (if you did not do this) as an example to get closer before having to switch to VHF.  You mentioned using 30 db attenuation with the portable flag when you got closer to the pole and wonder if you also removed the preamp at some point?

I do use the null on the portable flag but if I notice slight differences in direction between the peak and null I then trust the peak because nearby objects can alter the backside of the antennas pattern (might create a minor lobe where the null should be as an example and then you will notice 2 nulls, one on each side of the minor lobe that has developed).  I really only notice this when standing very close to my house as an example (like 10 feet from the house).  I have never found the main peak to be altered, and it’s therefore very trustworthy.  I normally just stand out on the sidewalk in front of homes or out at the street curb and this really works well (peak and null work great).

73,
Don Kirk (wd8dsb)


On Sat, Jun 19, 2021 at 4:09 PM Dave Hachadorian <k6ll.dave at gmail.com> wrote:

  About 10 days ago, a big noise started up on 80 meters, S9+15 dB with the preamp off and attenuator off on my K3. The noise was present 24/7.

  Today I found the source, reported it, and two hours later, it is fixed!  Here was my tracking procedure.

  I started out with the portable flag antenna from March 2021 QST.  The flag fed a 20 dB HF preamp that I have had for years (ARR P1-30/20VD).  The preamp fed a Tecsun PL-660 Shortwave Receiver.  I could hear the noise easily on 80 meters with that combination, and took a bearing on the null.  I drove in the direction of the null, and stopped to take additional bearings along the way, which told me that I was going in the correct direction.  The noise kept getting louder.

  Finally I got to a point where the noise was so loud on 80, even with a homemade 30 dB attenuator inserted in the line, that the flag was not giving me a good null.  At that point, I switched to my old 2 Meter mobile rig, which can receive on AM mode (Kenwood TM-261A), and for an antenna I used the back four elements of an old 2 Meter 11 element beam, lashed to a broomstick.  Unfortunately, the S-Meter on the TM-261A does not work in AM Mode, but I used the loudness of the audio signal to guide me.  I soon came to a pole where I could hear audible arcing with just my ear, without even listening to a radio!  At that point I hooked a Tiny SA Spectrum Analyzer to the 2 Meter antenna, just to use it as an S-Meter.  The Tiny SA is not very sensitive, but it showed a very raspy signal of –80 dBm all across the 2 Meter Band when the beam was pointed toward the pole.

  I called the power company and reported it as “arcing on a pole.”  I didn’t mention anything about radio noise.  They gave me an incident number, and said they would get on it.  Two hours later, I happened to look at Panadapter on the home station, and saw the noise disappear!  I zoomed back to the pole, and talked to the lineman, who told me that it was a bad connection.  He said he was going to put in an order to replace all of the hardware on that pole, which includes two transformers, lightning arrestors, and some other stuff.  A picture of the pole is attached, unless the reflector strips off attachments.  Incidentally, this pole is 2.1 miles from my house.

  Many thanks to all of the contributors on this reflector who have provided a valuable education on noise locating!

  Dave Hachadorian, K6LL
  Yuma, AZ



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