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Re: [RFI] Help finding a source

To: ny9h@arrl.net
Subject: Re: [RFI] Help finding a source
From: Michael Martin <mike@rfiservices.com>
Date: Thu, 05 Dec 2019 05:20:24 -0800
List-post: <mailto:rfi@contesting.com>
The mfj with the beam is probably the cheapest most convenient and best little 
RFI locator I've ever come across. I bought one back when they first came out 
and decided to do a little modifying. I added an amplifier between the radio in 
the antenna and an attenuator and then an external speaker. It was quite a good 
locator. The beam is quite fragile but for someone who just needs to find one 
noise every now and then I think this is about as good as you can get.

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On Dec 5, 2019, 4:52 AM, at 4:52 AM, Bill Steffey <ny9h@arrl.net> wrote:
>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
>   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)
>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,
>> 8.3 ms.
>> Don (wd8dsb)
>> On Wed, Dec 4, 2019 at 7:19 PM Michael Martin <mike@rfiservices.com>
>>> your noise is caused by loose hardware on the power line equipment.
>>> the three spikes you see per group represent three discharges per
>>> cycle
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>>> On Dec 4, 2019, 5:07 PM, at 5:07 PM, David Eckhardt
>>> wrote:
>>>> I give up.        It's power line discharge.
>>>> Dave - WØLEV
>>>> On Wed, Dec 4, 2019 at 11:24 PM Michael Morgan <michael@aa5sh.com>
>>>> wrote:
>>>>> I was hoping to get some help identifying a potential source for
>>>> RFI
>>>>> that started a few weeks ago.  I posted some pictures and audio
>>>> from
>>>>> 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
>>>> Blanker
>>>>> does  a decent job of removing the noise but on 40M it is a bit
>>>> random.
>>>>> I have tried turning the main breaker off to my house and use a
>>>> portable
>>>>> radio (Recent RS-918) off a battery and the noise is still there. 
>>>> did
>>>>> 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
>>>>> stopped for a minute while I've been typing this email for a
>>>> or so
>>>>> then started back up.
>>>>> Then at lunch today I took a break and remoted home since I saw
>>>> 10M
>>>>> 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
>>>>> wall-wart or battery charger.
>>>>> 73
>>>>> Michael, AA5SH
>>>>> _______________________________________________
>>>>> RFI mailing list
>>>>> RFI@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>> One very last try:  Copy to Word.  Eliminate image.  Copy test with
>>>> image.  Paste to email.  If this doesn't work, I give up:
>>>> In your third image, the audio spectrum, the groups (first peak of
>>>> first
>>>> 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
>>>> clip
>>>> also sounds suspiciously like 60 Hz discharge from the power
>>>> distribution
>>>> 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
>>>> in
>>>> this case.  In the time domain, I also usually detect an
>>>> decaying envelope for each discharge.  No so in this case.  But,
>>>> considering the period and sound, I'd guess its due to power
>>>> distribution
>>>> discharge in you area.  Walk the power lines with your
>>>> radio.  When you find a pole that is particularly, kick the pole
>>>> and
>>>> observe any change in the character of the sound on your radio.  If
>>>> change, its not at that pole.  Continue searching.  Also, damp
>>>> usually exacerbates the discharges as does dusty conditions.
>>>> Dave - WØLEV
>>>> --
>>>> *Dave - WØLEV*
>>>> *Just Let Darwin Work*
>>>> *Just Think*
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