I'm seeing a bunch of birdies on my 2 meter radio receivers. On the Airspy HF+ SDR it looks like a bunch of bright lines. On the roll-up J-pole antenna the overall noise floor is high (S7 or even S9) which makes working simplex stations very hard, as I discovered at the last simulated repeater failure test for our weekly ARPSC net.
I was able to make a contact with Steve N8AR via the South Lyon N8SL repeater from Ann Arbor. He could hear me just fine with my Kenwood sending, but I didn't hear him on that rig. So I tuned up the Airspy receiver to hear him.
I think I figured out some of it - I have a lot of ethernet ports on a switch in the attic, and I'm seeing a very strong signal on 125 MHz which am pretty sure is gigabit ethernet modulation leaking out of the unshielded (cheap) ethernet cables.
There is also noise at home on the AM band very distinctly in front of our house under the overhead lines. Ah, city life. I will bring my radios to the park in the summertime and not have these problems.
Looks like Andy G7UHN has some suggestions with ferrite cores
http://alloutput.com/amateur-radio/ethernet-rfi-noise-reduction/
based on this presentation from Joel W5ZN
https://w5zn.org/wp-content/uploads/2024/12/Noise-The-Grim-Reaper-of-Weak-Signal-Reception.pdf
Wes N8QM had a tip for inexpensive EMF sniffers, which can be used to measure field strength. I see some of them are specially designed for ghost hunting too (!)
