Re: S9 Noise in 40 Meter Band - How Can I Track it Down?

Neil Smith G4DBN

Hi Bill, is there any structure to the noise?  Does it have any characteristics which show up in AM mode or FM or SSB? Any periodic changes? Does the noise extend way out of the band? Any difference with an attenuator in line? If you look at the AF spectrum, do you see any peaks/troughs?  Any sign of the PK indicator being hit? Where does the noise start to drop off as you look LF and HF of 7MHz?  Any strong signals anywhere from DC to 55MHz?  Are you close to any TV broadcast stations with 6MHz channel spacing? Could be rusty-bolt mixing product of digital TV?

Any sign of 60Hz or 120Hz components in the noise?  Hae a look at the audio spectrum of the noise in each mode using Spectrum Lab or something to see if it is pure white noise, or has any modulation or periodicity.

Good luck.

Neil G4DBN

On 09/11/2019 17:21, Bill Alpert wrote:
I'm seeing and hearing loud noise sometimes at S9 on 40 meters. Strangely, 80 meters (as well as 20,10, etc.) is relatively quiet. Yes, I'm close to power lines, and yes, my antenna situation is less than optimal. Still, I'd like to understand the source (is it local?) and nature of the noise. Why is it strongest on 40 meters?? Walking the neighborhood with an AM radio didn't immediately point to any obvious source.

Note that I've tested this while on battery power with the main power of my house off. No change. I have noticed that the noise reduces slightly when I orient my magnetic loop antenna horizontally.

Would it be worth buying a cheap portable shortwave radio to try and locate the source. Any other testing ideas? Thank you!

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