FWIW, I built a 136-MHz Moxon from a QST article <QST_Mar_2001_p32-36>
to use with an Icom handi-talkie which covers the AM aircraft band. The
idea is that the Moxon has a deep dip in the rear which can be used for
precise DFing. Works fine, and I got 144/430 MHz transceive coverage
as a bonus ( though not with that antenna) for around $100.
73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.
On 12/5/2019 8:20 AM, Michael Martin wrote:
The mfj with the beam is probably the cheapest most convenient and best little
RFI locator I've ever come across. I bought one back when they first came out
and decided to do a little modifying. I added an amplifier between the radio in
the antenna and an attenuator and then an external speaker. It was quite a good
locator. The beam is quite fragile but for someone who just needs to find one
noise every now and then I think this is about as good as you can get.
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On Dec 5, 2019, 4:52 AM, at 4:52 AM, Bill Steffey <ny9h@arrl.net> wrote:
Hi,
mfj still sells a #852 which is nothing more than a VHF am receiver
with a dipole integrated onto the case.. .. Bought one new 14 years
ago
then found another at a hamfest for 40$ .
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
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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
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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*
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