[BVARC] QRM in new radio setup

[Steve Agee]

*Since you live in Missouri City, you are in the near field (relatively) 
of the high power transmitters for TV and radio. Have you tried a window 
filter in the coax to attenuate out of band signals?

N5ZUA
*
On 2/6/2021 11:37 PM, Mark Brantana via BVARC wrote:
> 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 
>> <mailto: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
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>
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