Mark, I had a bad laptop switching supply that caused the same broad spectrum white noise you are describing. It was plugged into the same outlet as the radio. My assumption was that it was a radio problem initially. Wiped out radio receive to S9+20 white noise.
I found it when I used a sw receiver and walked around looking for RFI sources. Turned out to be 6" from radio. 73, Kirk KK2Z > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 31 Jan 2021 19:33:20 -0600 > From: Mark Brantana <[email protected]> > To: BRAZOS VALLEY AMATEUR RADIO CLUB <[email protected]> > Subject: [BVARC] QRM in new radio setup > Message-ID: <[email protected]> > Content-Type: text/plain; charset="utf-8" > > I am reaching out for ideas on a radio issue. I have installed an IC-745 > Icom with an MFJ-2010 offset fed dipole. The power supply is a 20A MegaWatt > switching power supply, which is located right next to the radio. The > antenna is under some high power-lines with the long leg 90 degrees to the > power-lines. I used my nanoVNA to study the band SWR response, and > everything looks reasonable, though some small adjustments may need to be > made. Nothing is grounded as yet. > > Here?s my problem. I am only attempting to receive at this time and I get > consistent QRM white noise across all bands to the point where I can barely > pick out some voices, etc. > > I am confident that the antenna is properly connected due to my antenna > study. > I don?t believe the power lines are an issue, since the problem would > likely be more isolated show up as birdies at certain frequencies. > The radio settings seem to all be correct according to the manual. > Lack of grounding, but again the white noise is generally consistant > across the spectrum. Still, this could be the problem. > I have turned off my computer, so there no QRM from its power supply. > It does not help to have the switching power supply right next to the > radio, but other users give good reports on this model and no QRM issues > are mentioned. > I tried the radio at different times of the day on 20-m voice band, with > the same noisy result. > It could be the net result of a large number of small device transformers, > but I doubt it. > I turned off the wifi, and still no change. > > Hmm? I am a little stumped. Any thoughts or ideas? Personal experiences? > > Mark > N5PRD > >
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