*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@bvarc.org
<mailto:bvarc@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@bvarc.org <mailto:bvarc@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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