[ADXA] noise issue - take 2

[Jussi Eloranta]

Hi,

Just recorded the 160m noise on the panadapter. I was expecting it to be 
wide and all over the place. However, see attached. Bog is beverage on 
ground (wideband resonant) and invL is my inverted L (narrow resonant; 
SWR only OK at the bottom of 160m). You can see that both spectra are 
surprisingly narrow. They have center around 1.840 MHz (FT8 160m 
frequency, of course!) and extend to the sides by about 100 KHz. I was 
initially looking at this with my inv L and thought that, OK, that must 
be just the antenna response I am seeing. But now that I see the same 
thing with the BOG, I am not so sure what to make of this. If I scan 
more to the AM band, it seems that it is clear over there but then going 
further down in frequency I find another similar spot that is noisy.

So, is this power pole noise after all? And if not, what on earth could 
it be? It has the characteristic raspy tone with multiples of 60 Hz in 
it. On AM it sounds like the typical power line hum. All that fit power 
pole noise but the spectrum does not - I think. Furthermore, I do not 
hear this noise at all on 80m. This is not from my shack as I have 
turned off power and used the radio on battery power. I do hear 
something weak on 6m from far away but I have no idea if this is the 
same thing as what I see on 160m.

Jussi (aa6kj)
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