[ADXA] noise issue - take 2

[w5znjoel at gmail.com]

Jussi,

That is NOT power line noise. That is a noise being generated from another source likely from inside your home and could be a number of things but I can tell you that is NOT power line sparking noise.

You are correct, power line noise will occur over a broad range of frequencies and one in one isolated small segment. Start turning things off inside your home and shop and see if it disappears.

73 Joel W5ZN/ZF2ZN

-----Original Message-----
From: adxa-bounces at mailman.qth.net <adxa-bounces at mailman.qth.net> On Behalf Of Jussi Eloranta via ADXA
Sent: Monday, March 23, 2026 3:45 PM
To: 'ADXA' <adxa at mailman.qth.net>
Subject: [ADXA] noise issue - take 2

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)