[Elecraft] OT: 20M moving QRM

[Fred Jensen]

QRN, not QRM.  I can't see what the span is on your panadapter, but it 
has all the characteristics of an SMPS ... they're all over the place, 
you're probably seeing more than one.

When we were in CA on 5 acres in a rural area, I hosted the neighborhood 
wireless on my tower in return for free I'net at the backhaul speed [~90 
Mbps].  No problems except a few weak narrowband discrete birdies 
[clocks and LO's], and I learned where they were.

They replaced their equipment with new stuff and a new router powered by 
a Chinese RPOJ** SMPS in our equipment shed with a 24 VDC line up to the 
top of the tower resembling an 80 m Inv-L.  Looked just like your 
picture with a wide span on the P3, only MUCH stronger ... in the -70 
dBm range on 80, a bit weaker on 40 and 20.  Drifted slowly back and forth.

Since they had a number of neighbors as paying customers and really 
coveted the space at the top of the tower, I told them I'd wind chokes 
according to the "K9YC Recipe," and watch them install them.  Otherwise 
they could put in a "real" linear power supply.  The chokes did the 
trick.  If you can find the offending supply(s) which may be nothing 
more than wall warts, you might be able to choke the noise out.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

**RPOJ: Real Piece Of Junk

On Thu, 2016-03-03 at 10:05 -0800, David Ahrendts wrote:
 > Does anyone recognize this moving QRM? Last evening 6:30pm. Band is
 > dead. Ambient noise pretty calm. But notice the slowly moving noise
 > bumps on the K3S SVGA display. Might this be weather radar?   https:/
 > /vimeo.com/157616344
 >
 > David A., KK6DA, LA