[BVARC] QRM in new radio setup

Mark Brantana mark.brantana at gmail.com
Sat Feb 6 23:37:34 CST 2021


Tonight I hooked up my little TH-F6A to the same antenna and got the same noise. I do have to test out my radio, but I am 85% convinced that it is QRM from a pole transformer located about 25 ft from the long end of my OFDP. This is a reasonably new transformer, since they replaced it about 5 years ago when the old one blew. Anyone have experience with getting the electric company to do a RFI survey?

On the down side, I carried my AM radio to my back yard and heard no detectable interference. This is turning into a real mystery. 

Mark
N5PRD

> On Feb 3, 2021, at 6:55 PM, Gus Bernard via BVARC <bvarc at bvarc.org> wrote:
> 
> 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 <mailto: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
> ________________________________________________
> Brazos Valley Amateur Radio Club
> 
> BVARC mailing list
> BVARC at bvarc.org <mailto:BVARC at bvarc.org>
> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org <http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org>
> ________________________________________________
> Brazos Valley Amateur Radio Club
> 
> BVARC mailing list
> BVARC at bvarc.org
> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.bvarc.org/pipermail/bvarc_bvarc.org/attachments/20210206/d1bc2059/attachment.htm>


More information about the BVARC mailing list