[RFI] Guidance on finding noise?

[K9MA]

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 at 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 at contesting.com> On Behalf Of Kenny Silverman
>> Sent: Saturday, January 11, 2020 8:03 PM
>> To: jwin95 at yahoo.com
>> Cc: RFI <rfi at 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 at 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 at 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 at sdellington.us