[ADXA] noise issue - take 2

[Stan Stockton]

Perhaps try making a small, 2-3 foot diameter loop antenna that has a sharp
null and then use it from 3 locations on your property to pinpoint the
source?

Stan, K5GO

On Mon, Mar 23, 2026 at 4:07 PM EJ Jones via ADXA <adxa at mailman.qth.net>
wrote:

> I’m certainly not an expert of noise, but I had something similar with an
> SDR receiver. I put a high pass filter on it to block the a.m. band and it
> got a lot better.   Wish you were a little bit closer and I’d lend you a
> high pass filter to stick on there and see what happens.
> EJ
>
> Get Outlook for iOS <https://aka.ms/o0ukef>
> ------------------------------
> *From:* adxa-bounces at mailman.qth.net <adxa-bounces at mailman.qth.net> on
> behalf of Jussi Eloranta via ADXA <adxa at mailman.qth.net>
> *Sent:* Monday, March 23, 2026 3:45:28 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)
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