I can't stress enough the value of listening to the noise received by
your HF receiver at the home QTH while you are listening to tracking
receivers.There is always a pattern to the noise; when you find a source
that matches, you have the right one.
I do this by re-transmitting the audio from the home receiver either on
a VHF radio (with control operator) or to my cell phone.There are
expensive instruments which will record a noise "signature", but I doubt
they work any better than just listening as above. It's important that
the receiver be in AM mode, AGC off, RF and AF gain adjusted so nothing
is getting overloaded.
73,
Scott K9MA
On 1/12/2020 19:01, Kenny Silverman wrote:
Hi Lee, thanks for your story! KC4D has the DX Engineering vertical array
laying on the ground so we may look at that as the sense antenna. The current
project we were looking At was a better 2m detection system just in case...
but I really like the SDR in a truck Which Jim is also strongly advocating
looking at the spectrum
Not sure if you or others asked about turning off the house power, and yes
that’s been done. The noise does not go away.
We’re regrouping on our test equipment and process. We are really appreciative
of all the great input on our quest
Regards , Kenny K2KW
On Jan 12, 2020, at 1:14 PM, Lee STRAHAN <k7tjr@msn.com> wrote:
Kenny and All,
I have a noise here in Central Oregon that sounds very similar to the one you
are chasing. There is a wood products plant about 2000 feet from my shack and
antennas. The noise is worst on 160 meters and extends up to about 5 MHz and
not detectable above that range as far as I know. It is a raspy sizzling noise
that changes all its sidebands as you travel along the power lines. I tried low
frequency loops and VHF etc with no success of any antennas pinpointing the
problem. Even a professional locator group paid by the power company tried with
no success. I knew I could easily hear the noise on my car AM radio at the top
of the AM band and multiple trips right out my driveway toward the plant gave
indication but no actual hotspot. I make high impedance antennas (you could
call one an e-probe) so I put a 4 foot converted vertical on the back of my
pickup truck with a wideband high impedance amplifier and the suitable power
injection. I fed this to an SDR-IQ radio and laptop combination. What I could
see of this interference was astounding. The computer display showed hundreds
of signal peaks that varied by a very large amount as I moved along the power
lines. This may be the reason you cannot pinpoint (in my case) the exact
location because of the many varying sidebands included in the interference.
With the wide band display I was able to drive 1 1/2 miles down the road where
I could still see the interference, turn around and drive right to the business
with a peak of wide bands of noise right at the power pole feeding that
building. These power lines also feed my property. At first I thought it was
their 100 HP air compressor but when they shut it off the noise remained. I now
suspect another commercial device they have which is a large glue pot with a
continuous temperature controlled heater. At least the company is working with
me and allowing me to help pinpoint the offender. I first gave them the
introduction letter from the NK7Z site or ARRL I cannot remember which. They
actually consulted with someone that gave them the opinion that they indeed
needed to fix the problem. They did not share with me whom they spoke with.
The point to all this is try looking at the noise with a SDR radio that
should give you a wider bandwidth picture. It sure worked for me under very
similar circumstances.
Lee K7TJR OR
-----Original Message-----
From: RFI <rfi-bounces+k7tjr=msn.com@contesting.com> On Behalf Of Kenny
Silverman
Sent: Saturday, January 11, 2020 8:03 PM
To: jwin95@yahoo.com
Cc: RFI <rfi@contesting.com>
Subject: Re: [RFI] Guidance on finding noise?
The noise is mainly on 160. Slight to no noise on 80/40, and no detection at AM
VHF.
Regards , Kenny K2KW
On Jan 11, 2020, at 10:16 PM, AA5CT <jwin95@yahoo.com> wrote:
Kenny,
Did you whip out your VHF and UHF beams with an AM rx mode receiver
once close to the suspect poles? That is the only way, and it is a
conclusive way, that I have found to ID noisy power poles once the HF
DF loop gets you in the area of the noise source.
de AA5CT
.
.
On Saturday, January 11, 2020, 9:03:04 PM CST, Kenny Silverman
<kenny.k2kw@gmail.com> wrote:
KC4D,N3AC and N3CW went hunting with a KX3 and a DX Engineering Amplified RX loop and again
didn’t find anything conclusive. Basically they said the loop performed about the same
as one of the AM radios we have that’s fairly directional.
We’ve been looking so many times that we’re getting frustrated. There
are a few noisy clusters, but we can’t find a specific pole or house.
Nor can we assess if the noisy areas are actually the key offender(s)
Do we call in the clusters we found ? Or do we really need to pinpoint the source(s)
better before we ask for crews to come out? We’re concerned about crying wolf
and/or giving a list of more than a dozen poles for the power company to look at.
Regards , Kenny K2KW
P.S. the only success so far is fixing my subject line typo 🤓
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Scott K9MA
k9ma@sdellington.us
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