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Re: [RFI] Help finding a source

To: rfi@contesting.com
Subject: Re: [RFI] Help finding a source
From: Bill Steffey <ny9h@arrl.net>
Reply-to: ny9h@arrl.net
Date: Thu, 5 Dec 2019 07:52:52 -0500
List-post: <mailto:rfi@contesting.com>

mfj still sells a #852   which is nothing more than a VHF am receiver with a dipole integrated onto the case.. ..  Bought one new 14 years ago   then found another at a hamfest for 40$ .

After showing Commonwealth Edison rfi guy my panadapter and the beam heading stuff, I took him into the neighbors back yard with this little box with a meter & headphones. Straight to the bad pole. He said it worked better than the Radar Engineers equipment ...( not quite) ....and at that price his boss could get a few MFJs rather than passing around the expensive boxes... at least till need was indicated.  For powerline noise it is nothing but an aircraft AM receiver with a dipole ...which you retract for attenuation as you approach the suspect.  WORKS GREAT....   They sell the same meter with a beam for more money,,,


On 12/5/2019 4:24 AM, Don Kirk wrote:
Hi Michael,

You mentioned three discharges per half cycle, but looks like it would be
three discharges every other half cycle (if it is indeed power line
equipment) since the period between the groups of 3 is around 16.7ms, not
8.3 ms.

Don (wd8dsb)

On Wed, Dec 4, 2019 at 7:19 PM Michael Martin <mike@rfiservices.com> wrote:

your noise is caused by loose hardware on the power line equipment.
the three spikes you see per group represent three discharges per half

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On Dec 4, 2019, 5:07 PM, at 5:07 PM, David Eckhardt <davearea51a@gmail.com>
I give up.        It's power line discharge.
Dave - WØLEV

On Wed, Dec 4, 2019 at 11:24 PM Michael Morgan <michael@aa5sh.com>

I was hoping to get some help identifying a potential source for some
that started a few weeks ago.  I posted some pictures and audio clips
20 and 40 meters on my webpage.  Thought it may be easiest there I
hope it
is ok.  https://www.aa5sh.com/?p=328

I tried to get some screenshots from my 7610.  On 20M the Noise
does  a decent job of removing the noise but on 40M it is a bit two
I have tried turning the main breaker off to my house and use a
radio (Recent RS-918) off a battery and the noise is still there.  I
walk around my property and noticed no real differences.  The odd
thing is
it's kind of random.  It has been going to 30 Mins or so and it just
stopped for a minute while I've been typing this email for a minute
or so
then started back up.

Then at lunch today I took a break and remoted home since I saw where
was open and there was no noise for that 30-40 minutes.

I appreciate any guidance you can provide.  In my years of radio
anytime I
have had noise problems I have always been able to narrow it down to
wall-wart or battery charger.


Michael, AA5SH
RFI mailing list

One very last try:  Copy to Word.  Eliminate image.  Copy test with no
image.  Paste to email.  If this doesn't work, I give up:

In your third image, the audio spectrum, the groups (first peak of
group to first peak of next group) is 17.5 ms.

The period on one cycle at 60 Hz is 16.67 ms.  Very close.  The sound
also sounds suspiciously like 60 Hz discharge from the power
somewhere in your vicinity.  I usually detect this at 120 Hz as the
discharge occurs at both the + and - peaks of the sine wave.  But not
this case.  In the time domain, I also usually detect an exponentially
decaying envelope for each discharge.  No so in this case.  But,
considering the period and sound, I'd guess its due to power
discharge in you area.  Walk the power lines with your battery-powered
radio.  When you find a pole that is particularly, kick the pole hard
observe any change in the character of the sound on your radio.  If no
change, its not at that pole.  Continue searching.  Also, damp weather
usually exacerbates the discharges as does dusty conditions.

Dave - WØLEV


*Dave - WØLEV*
*Just Let Darwin Work*
*Just Think*
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