[RFI] Fw: Mystery Noise (Aren't they all)

[Michael Carter]

Forgot to send this to the list - only sent
to Wes at first.

73,
Mike, K8CN
________________________________
From: Michael Carter <Mike.Carter at unh.edu>
Sent: Thursday, March 28, 2024 9:36 AM
To: Wes Stewart <n7ws at yahoo.com>
Subject: Re: [RFI] Mystery Noise (Aren't they all)

Thanks for the Radar Engineers screen video, Wes.

I don't see a time scale on that scope depiction
of the detected audio, but the period of reduced
amplitude of the RFI signal may correspond
to what your previous waterfall screenshot
revealed.  The dropout isn't audible in the audio,
but it appears to be present in the scope view.
The envelope modulation is certainly evident.

73,
Mike, K8CN
________________________________
From: RFI <rfi-bounces+mike.carter=unh.edu at contesting.com> on behalf of Wes Stewart via RFI <rfi at contesting.com>
Sent: Wednesday, March 27, 2024 5:01 PM
To: RFI List <rfi at contesting.com>
Subject: Re: [RFI] Mystery Noise (Aren't they all)

CAUTION: This email originated from outside of the University System. Do not click links or open attachments unless you recognize the sender and know the content is safe.


 As promised, a follow up. There has been no improvement in my situation. One major problem is the way the electric coop operates; the RFI guy finds a suspect, contacts someone else who is supposed to dispatch a crew to address the issue.  If the repair people show up, they do something that may or may not correct the problem and then go away.  I wait a few days and then follow up to find nothing is resolved.  Rinse and repeat.
One thing that has happened is that I contacted our water coop that owns the pumps that are supplied by the electric coop.  After several fits and starts I was able to get the RFI on site while a water guy turned off the variable frequency motorized pumps.  The RFI was unchanged.  This is unfortunate, I was hoping it was a pump because I think the water guys would be more cooperative than the electric guys.
So as it stands the RFI guy came to my shack again and hooked his Radar Engineers RX to my antenna.  I took a short iPhone video of what is heard and displayed.
https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dropbox.com%2Fscl%2Ffi%2Frvjv8nf1eoj8w75stltx6%2FRadar_Engineers_Video.mp4%3Frlkey%3Dn5y7ddr8odb7mw4cl68ckmx81%26dl%3D0&data=05%7C02%7Cmike.carter%40unh.edu%7C249eb023dd03427cb72708dc4ea13640%7Cd6241893512d46dc8d2bbe47e25f5666%7C0%7C0%7C638471701505609993%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=ngQTQbhHo1dDC54Qok22U8RaYGPghzsywBext%2BgcFIE%3D&reserved=0<https://www.dropbox.com/scl/fi/rvjv8nf1eoj8w75stltx6/Radar_Engineers_Video.mp4?rlkey=n5y7ddr8odb7mw4cl68ckmx81&dl=0>
Note that the strength indicator is showing -47 dBm.  S9 is standardized to -73 dBm.  So this is 26 dB over nine, which is about what I measure.
Wes  N7WS


    On Thursday, March 7, 2024 at 12:51:51 PM MST, Wes Stewart <n7ws at yahoo.com> wrote:

  Hi Chris,

Thanks for checking this.  I can confirm, much to my chagrin, that your numbers are correct.

Everybody


Armed with this I just got back from walking the line from the corner pole to the west and then south to the pumping station.  I should note that with more attention I saw that the line to the west is three phase all the way, but does seem to carry a neutral.  One phase is feeding "my" line that runs to the north and another phase feeds the line running to the south.

With my Sony receiver tuned to 1705 kHz and the loopstick active, there was plenty of sensitivity, but little directivity, to hear the raucous noise under the pole feeding the pumping station.  Subject to changing my mind, I'm now 99% sure the source is there. Whether it's the power co-op or the water co-op at fault remains to be seen.

More to follow.



    On Thursday, March 7, 2024 at 08:19:16 AM MST, Chris L. Parker <parker601 at earthlink.net> wrote:

 Hi Wes,

To answer your question, experience (been there, done that) and experimenting.
I pulled out the old Wavetek 3001 signal generator to confirm the antenna transition frequency yesterday.
Don's (WD8DSB) very effective flag antenna is now a kit on DXEngineering.
Specified usable for DF down to 1.8 MHz.
The flag will need a preamp for use with the Sony 7600GR (and blocking cap). They sell a preamp as well.
I built a much more "stealthy" 6-inch ARDF loop for my MW DF work. (QST, Sep 2005, Dale Hunt, WB6BYU)
I have an unidentified 160 meter RFI source in a strip mall 1/4 mile away from me.
Noise conducts (not radiates) through the powerlines towards my residence. Very tricky to locate due long wavelength.
I suspect my RFI is HVAC, commercial refrigeration, or similar variable speed drive electric motor.

Hope this helps.
Chris
AF6PX

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