nasty power line related hash in Loudoun (Dominion territory)...

[Rob Seastrom]

Greetings Tacoistas,

Within the past month, there has been an annoying signal taking a bite out of 80m here at the AI4UC QTH.  It's strong enough to be disturbing 40m as well as a whiffo on 20  (screen shots below).  Doesn't change much if at all day vs. night (or with the weather) which is causing me to partially discount the notion of solar panels causing it, but read on...

Check-ins with a friend down in Northern Neck and closer didn't find anything there, so I figured it was local.

Hoping that it was something in the house so I could kill it, I tried sniffing around the house with a TinySA with a short antenna on it.  Didn't find anything except that my offline 3kw UPS will put out a decent amount of hash when I pull the house's main breaker.  Disconnected the antenna from the radio - problem went away.  Connected the antenna to the TinySA and I could see the haystack, though the TinySA is not nearly as sensitive as the Flex 6400.

Hooked the TinySA to a 75m Hamstick on a magmount on the roof of the truck (which is a mechanical diesel - it is an AF noise generator not an RF noise generator).  Went for a drive.  Signal strength occasionally drops to -80 but sometimes as high as -57 dBm, and seem correlated with the 19kv feeder that we're on.

I'm wondering if someone got a new set of solar panels with a noisy inverter(s), or maybe Dominon is trying to pull a fast one with BPL-like technology for SCADA.

Would welcome commentary and advice on next steps - I'm thinking that doing some driving around with a GPS and NanoVNA-Saver reading from the TinySA to create a heat map may be constructive.

80m screen shot (the yellow stripe right at the marker is expected; it's the FT8 watering hole).  The cadence of the horizontal bands to the left changes periodically to as low as one every few seconds.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: PastedGraphic-1.png
Type: image/png
Size: 3919546 bytes
Desc: not available
URL: <http://lists.amrad.org/pipermail/tacos/attachments/20241130/73392aef/attachment-0004.png>
-------------- next part --------------


40m harmonic issue:on 40:

-------------- next part --------------
A non-text attachment was scrubbed...
Name: PastedGraphic-2.png
Type: image/png
Size: 4061983 bytes
Desc: not available
URL: <http://lists.amrad.org/pipermail/tacos/attachments/20241130/73392aef/attachment-0005.png>
-------------- next part --------------

30m appears to be clean, there is a hint of the harmonics on 20m...

-------------- next part --------------
A non-text attachment was scrubbed...
Name: PastedGraphic-3.png
Type: image/png
Size: 4293368 bytes
Desc: not available
URL: <http://lists.amrad.org/pipermail/tacos/attachments/20241130/73392aef/attachment-0006.png>
-------------- next part --------------


-------------- next part --------------
A non-text attachment was scrubbed...
Name: PastedGraphic-4.png
Type: image/png
Size: 4057094 bytes
Desc: not available
URL: <http://lists.amrad.org/pipermail/tacos/attachments/20241130/73392aef/attachment-0007.png>
-------------- next part --------------


Any thoughts would be greatly appreciated.

73 de AI4UC