[RFI] Powerline noise question

[Hare, Ed, W1RFI]

Yes, many noises can sound the same.  Also, many noises do NOT propagate for any significant distance from the source.  For the most part, if a noise is conducted onto the AC mains in the differential mode, it decays at nearly 60 dB/distance decade from the source.   Our testing engineer and I recently had a chance to visit a local solar farm.  At the fence, near the inverter electronics, we found S9 noise, but it was inaudible on a portable SW receiver when we were 10 feet away, so noise can decay rapidly with distance.

This is a problem that electric utilities encounter all the time.  They get a complaint, go to the area, find noise and fix it... well... fix most of it, but the noise sources they fixed were not ones the amateur could hear.

There are several ways to get reasonable correlation.

For sparking noise sources, get a noise signature at the affected station and compare it to noises in the field.

For sources that come and go in a regular pattern, ie 1 second on, 3 seconds off, it is reasonable to assume that a similar noise found in the field nearby is the source.

For switching power supplies, the spacing between the noises vs spectrum can be a clue, but many devices could have similar spectral signatures.

If you can clearly hear the noise on a mobile antenna at the ham station and can clearly hear it all the way to the suspect source, that can also be a reasonable correlation.

Ed

________________________________
From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> on behalf of Frank W3LPL <donovanf at starpower.net>
Sent: Saturday, December 31, 2022 6:56 PM
To: Richard <richard at karlquist.com>
Cc: rfi <rfi at contesting.com>
Subject: Re: [RFI] Powerline noise question

Hi Rick,

I never attempt to guess based on the sound of the RFI, I always
use geolocation techniques to discover the location of the source.

Good luck!

73
Frank
W3LPL



----- Original Message -----
From: "Richard" <richard at karlquist.com>
To: "Don Kirk" <wd8dsb at gmail.com>, "Frank W3LPL" <donovanf at starpower.net>
Cc: "rfi" <rfi at contesting.com>
Sent: Saturday, December 31, 2022 9:49:50 PM
Subject: Re: [RFI] Powerline noise question

I have attached an mp3 of the noise to my reply.
I hope it propagates to Don, at least.

73
Rick N6RK

On 12/31/2022 8:55 AM, Don Kirk wrote:
> Hi Richard,
>

> how a conventional Xenon tube flash circuit works in photography.  Can
> you upload a recording of your noise burst so we have a better idea of
> what you are hearing/seeing?  But as others have said I never try and
> guess what the source is other than to try and determine if it is power
> line related noise because if it's not power line noise then I might not
> pack my vehicle with as much VHF and UHF DF gear.
>
> Don (wd8dsb)
>
>
_______________________________________________
RFI mailing list
RFI at contesting.com
http://lists.contesting.com/mailman/listinfo/rfi