Wow, that was a bad one! The weaker ones can be much harder to find, but
still troublesome.
73,
Scott K9MA
On 6/19/2021 4:19 PM, Dave Hachadorian wrote:
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@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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Scott K9MA
k9ma@sdellington.us
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