Narrow band noise in lower HF spectrum

  • 1
  • Question
  • Updated 3 years ago
  • (Edited)
I love my new 6500, but it has allowed me to see how really bad the HF spectrum is polluted in my area.  I have NO problems with the 6500, but I figured I'd ask here to see if anyone also has similar pollution.

See screen capture here:

https://www.youtube.com/watch?v=E_r9cO36kho


Both spectrums are centered about 5.3 MHz, with the lower being wide-band.  You can see the bands appears in groups of four, with about 98 kHz separation.  Within each group they do not appear be harmonically related as they drift slowly +/- 1 kHz from one another, though the spectral shapes are nearly identical.  AM demod sounds like electrical noise.

It's not coming from my house as I can kill all power and pick them up with my battery powered KX3.

It's not the street lights as I checked this morning after turn off; still there.  The noise is there 24/7, which I suppose is good since that means it is localized.

I am receiving with an active loop in back yard away from house, and there is a ground mounted HV transformer in the back yard with very wide band noise at 4 MHz, which I can null out, but it is not that strong.  That does not work with this narrow band noise, which I suppose means it is not broadside to the loop; i.e. coming from above.

I plan on building a simple, hand held, loop this weekend with which I can verify transformer noise and get the power company out here.

I have seen similar types of narrow band noise in switching power supplies as the switch transient generates a wideband comb with spacings at switch frequency.  Something similar may be going on here.

Any thoughts?  Has anyone seen anything similar?  I suppose I should first get the power company to check the transformer first, then see if that is somehow related to this, but from what I have read on power line noise, the arcing will generate wide band noise.

The cable company has strung these blasted WiFi APs on the telephone poles along my street.  Maybe it could be those.  I believe there are four noise source, all at slightly different frequencies, that is causing this problem.  The spectral shape being identical leads me to believe it is identical hardware.
Photo of KD4HSO

KD4HSO

  • 52 Posts
  • 3 Reply Likes

Posted 3 years ago

  • 1
Photo of Terry Tankersley

Terry Tankersley

  • 56 Posts
  • 4 Reply Likes
Can u put up a picture of the noise, I think I have the same thing. I will post a picture.
Terry
K7ny
(Edited)
Photo of KD4HSO

KD4HSO

  • 52 Posts
  • 3 Reply Likes
(Edited)
Photo of Terry Tankersley

Terry Tankersley

  • 56 Posts
  • 4 Reply Likes
(Edited)