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Author Topic: RFI on all HF bands  (Read 9176 times)
N6DIY
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Posts: 10




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« on: October 05, 2015, 10:34:40 AM »

I am experiencing rfi that is repetitive across all HF bands.
I unplugged everything to see if the QTH was the problem and answer is no.
I checked the transceiver (ICOM 7800) and it is not the problem.
I am seeing lines going left to right at approximately 45 to 50 degrees periodically across the whole band via waterfall display (estimated spacing at this time is max. of 3.33 KHz).
Sometimes it is double lines.
There looks to be some modulation on the noise that now rides at approximately -70 dBm.
A friend of mine lives 60 to 65 miles from my QTH and he is picking up the same thing on his ICOM pro III.
Any ideas or suggestions from the community?
Thank you.
Tim  
N6DIY
« Last Edit: October 05, 2015, 11:08:52 AM by N6DIY » Logged
K5LXP
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« Reply #1 on: October 05, 2015, 07:27:40 PM »

Quote from:  link=topic=105539.msg873540#msg873540 date=1444066480
I am experiencing rfi that is repetitive across all HF bands.

This is significant.  160 through 10M?  Or higher?  What kind of antenna do you have?

Quote
I unplugged everything to see if the QTH was the problem and answer is no.

But did you try turning off the main circuit breaker or service disconnect?


Mark K5LXP
Albuquerque, NM

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N6DIY
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Posts: 10




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« Reply #2 on: October 05, 2015, 09:30:30 PM »

I have not checked 6m, but will when I get a chance later this week.
I have pulled the main breaker with no change. I am using a vertical at this point in time.
In discussing this today, I did discover that I need to pull batteries on some remote weather systems.
I have acquired an ICOM R1 and plan to walk the fence lines and check power poles, etc. later this week. I will report my findings.
Another amateur in Ft. Worth suggested checking for ATT Uverse nodes.
Thank you.
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K2OWK
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Posts: 1279




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« Reply #3 on: October 05, 2015, 09:54:11 PM »

Check for electric fences in your location. Some put out signals on all the bands if not properly installed.

73s

K2OWK
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N6DIY
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Posts: 10




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« Reply #4 on: October 05, 2015, 10:14:41 PM »

I run electric fences, but I powered them all down with no change seen on the transceiver.
I do see the fence pulse, but it is not even close to what I am seeing now.
When I am working a rare station I do turn the fences off.
Thank you.
« Last Edit: October 06, 2015, 03:55:53 AM by N6DIY » Logged
N6DIY
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Posts: 10




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« Reply #5 on: October 06, 2015, 09:49:22 AM »

What ever was causing the RFI has disappeared this morning.
I will verify later tonight that it is indeed really gone.
Maybe the FCC field office got wind of this. They are very active in Dallas.
Thank you all for your comments and suggestions.
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N6DIY
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« Reply #6 on: October 06, 2015, 04:21:42 PM »

It is back tonight and several more amateurs are picking it up around Dallas. Still being picked up about 65 miles from me North of Denton.
I do see it still on all HF bands including 6m.
Thank you.
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K5LXP
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« Reply #7 on: October 06, 2015, 07:37:31 PM »

I do see it still on all HF bands including 6m.

It must be very close to you then - line of sight.  Something this strong and high in frequency should be straightforward to DF.


Mark K5LXP
Albuquerque, NM
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N6DIY
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« Reply #8 on: October 07, 2015, 03:34:41 AM »

I received a call late last night from an amateur about 10 miles from me in town where it s even stronger and louder in the noise floor. I have received reports where it seems to go down and then back up during the day.
We are putting gear together to try some DF this weekend.
Use on HF around this area of the country is a disaster at this time.
I will report what we find.
Thank you.
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N6DIY
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« Reply #9 on: October 10, 2015, 06:34:58 AM »

I have proved that the house and shack are not causing this.
Talked to FCC field office and they believe it is a switching power supply.
In fact the last time they saw this was an AT&T uverse power supply that was bad.
They are highly interested in this since several amateurs in the area are picking up the same interference.
The other comment made by FCC was that the new generation of fence chargers are not the old pulse type, but are a pulse to an rf circuit that radiates. They have had to investigate quite a few if these.
I tried df with a portable receiver in am mode, but was getting to much broadcast station bleed through.
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N6DIY
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Posts: 10




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« Reply #10 on: October 12, 2015, 08:38:22 AM »

I placed a 102" whip on a mag mount yesterday, connected an ICOM 706 to it and drove around to see if we could find the RFI source. We used the hottest frequency from the QTH that was 18.189 MHz.
While driving in front of the local elementary school the noise jumped and sounded exactly like what I am hearing on my transceiver at my QTH.
It turns out it is the ATT distribution boxes. I could not tell if they added a Uverse node here, but it is highly probable that they did.
The interesting thing we noticed is the close proximity of the source to the power lines.
We suspected coupling to the power lines which is why other amateurs in the area 60+ miles away are picking this RFI up. Power lines can make for a great HF antenna.
FCC has been notified.
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NK7Z
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« Reply #11 on: October 12, 2015, 09:09:53 AM »

I placed a 102" whip on a mag mount yesterday, connected an ICOM 706 to it and drove around to see if we could find the RFI source. We used the hottest frequency from the QTH that was 18.189 MHz.
While driving in front of the local elementary school the noise jumped and sounded exactly like what I am hearing on my transceiver at my QTH.
It turns out it is the ATT distribution boxes. I could not tell if they added a Uverse node here, but it is highly probable that they did.
The interesting thing we noticed is the close proximity of the source to the power lines.
We suspected coupling to the power lines which is why other amateurs in the area 60+ miles away are picking this RFI up. Power lines can make for a great HF antenna.
FCC has been notified.
Did you notify ATT?  That might be the best way to get faster corrective action.
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Thanks,
Dave
Amateur Radio: RFI help, Reviews, Setup information, and more...
https://www.nk7z.net
QRP4U2
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Posts: 262




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« Reply #12 on: October 25, 2015, 03:02:16 PM »

Not unusual.

A friend of mine in Texas and myself (here in Iowa) have both seen this signal which appears to have about 50% digital and/or tone modulation at times.

We figured it's the Guvment.

Phil - AC0OB

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AC0OB - A Place Where Thermionic Emitters Rule!
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N6DIY
Member

Posts: 10




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« Reply #13 on: October 30, 2015, 08:52:25 AM »

FCC has verified my finding.
AT&T is coming out when it is not raining which is probably late next week.
They are going to shut the box down and run it directly off batteries bypassing switching power supplies.
This should determine if is them or the new remote reading power meters.
We are keeping our fingers crossed that it is not a wifi extender using the house wiring.
FCC is interested in finding out if this problem is being seen elsewhere, i.e. a bigger problem.
Stay tuned.
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NO9E
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« Reply #14 on: December 15, 2015, 05:12:02 PM »

N6DIY:
Did ATT come?
Ignacy, NO9E
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