Re: Interesting phenomena or has something changed?

Allan Isaacs

That brings back memories of the early 60s when we were operating G3OUL in the Students Union at Liverpool University.

We kept breaking through into the Tannoy system.

It turned out to be diode-like corrosion in the lead roof of the building if my memory serves me right.

Allan G3PIY


From: [] On Behalf Of N8CVW
Sent: 05 February 2021 13:47
Subject: Re: [SDR-Radio] Interesting phenomena or has something changed?


just a knee jerk advice ...


maybe listen with a low sensitivity wide band antenna, eg youloop, maybe short a whip, straight into the receiver, no preamp, nothing to IMD


to find out what actual signal is present 


from what (little) i know the culprit could be corrosion acting like a diode 




On Feb 5, 2021, at 8:36 AM, Kriss Kliegle KA1GJU <kliegle@...> wrote:

I've noticed in the last few weeks that my server (KA1GJU @ PCARC) is getting QRM from a nearby 5KW AM BC station on 1540 kHz 5.2mile (8.4km) miles away. This installation was relatively QRM free until recently. I've noticed this station creeping in all over the bands, and it's not just the Airspy, it's also on the SDR-iq. The antenna is an EFW of ~200' long, with a 9:1 unun, grounded at the unun and long length of 1/2" 75 ohm CATV hardline to shack.

Right now, at 1311z it's slowly fading in and out on 14230 kHz (9.24 harmonic of 1540kHz?). There is some SSTV under it giving false S-meter readings, but the waterfall shows the slow fades, images are ~ one minute apart. Slow QSO is normal for this time of day since the Sun rose up just over an hour ago.


Do you think the issue is on my end with something in the antenna/feedline or does the AM BC station have issues?
Open ground connection perhaps? I would have to trudge out in snow shoes to check the antenna, recent storm dumped on us few days ago.

73 Kriss KA1GJU


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