[BVARC] QRM in new radio setup

Gus Bernard gnelnard at gmail.com
Wed Feb 3 18:55:39 CST 2021


What Rick says.  Then try taking it portable, away from the QTH and power
lines.

Gus, K5GMB

On Sun, Jan 31, 2021 at 7:33 PM Mark Brantana via BVARC <bvarc at bvarc.org>
wrote:

> 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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