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:
>Hi,
>
>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,,,
>
>https://www.mfjenterprises.com/Product.php?productid=MFJ-852
>
>
>
>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
>>> cycle
>>>
>>> Get BlueMail for Android
>>>
>>> On Dec 4, 2019, 5:07 PM, at 5:07 PM, David Eckhardt
><davearea51a@gmail.com>
>>> 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
>some
>>>> RFI
>>>>> that started a few weeks ago. I posted some pictures and audio
>clips
>>>> 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
>two
>>>> 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.
>I
>>>> 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
>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
>>>> 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
>to
>>>>> 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
>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
>>>> 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
>sound
>>>> 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
>not
>>>> in
>>>> 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
>>>> distribution
>>>> 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
>>>> and
>>>> 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*
>>>> _______________________________________________
>>>> RFI mailing list
>>>> RFI@contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>> _______________________________________________
>>> RFI mailing list
>>> RFI@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>
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