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bad qrm

normd

2E0FAS
Mar 4, 2013
3
0
11
England
I am having a really bad problem with interference on every HF band exept 10 meters. See youtube vid, I think it's a neighbours plasma tv or something but not sure as it's constant all day, i know it's nothing in my house so wondering if changing my antenna or something will help, i am using an off center fed dipole with a 4:1 balun at the feed point which i have read can be noisy. I have seen this sites review of the MFJ-1025 Noise Canceller so maybe an idea but thats expensive if it does not work. Any thoughts?

Terrible QRM - YouTube
 

That sounds like a plasma TV for sure. The noise canceller can work. You will have to play around with the pickup antenna to find an optional sweet spot.

Noise cancellers work, but take patience to master. I had an ANC-4 that worked like a champ at my last QTH. MFJ makes a noise canceller, but I am unfamiliar with that model. I believe there is a review of it on this site.

EDIT: MFJ-1026 Review:

http://www.worldwidedx.com/product-...6-noise-canceling-signal-enhancer-review.html

Both models have a telescopic antenna for local noise and and external antenna connector to pick up noises that are farther away. The external pickup antenna needs to be tweaked and positioned so it is broadside to the source. It may also need to be positioned horizontal or vertical depending on the offending noises polarity. Most people get frustrated by the unit because they don't fidget with it enough to obtain the optimum settings.

Depending on how well you know the people and how large the TV and it's price...maybe you can convince them how shitty a plasma TV really is and buy them an equal size LCD TV.

Many HAMS immediately cry part 15 interfence rules. In reality. harmful interference from part 15 devices do have allowable distance and microvolt signal levels. If the offending device is very close, like the next room away in an apartment, you might have to suck it up.

The noise I had was from a leaky powerline insulator that was eventually fixed by my utility. I had another source that was coming from a vacant house that was for rent. The doorbell transformer went bad and was sending a 2-3 second buzzing sound every few seconds. It was about 300' feet away. I called the landlord and he came out and disconnected it for me. I thanked him and shook his hand, lucky for me. Those doorbell transformers will drive you absolutely crazy. Plasma interference will completely demoralize an operator.

The ARRL has all the rules regarding RFI and harmful interfence regulation on their site. You can also call Mike Gruber @ ARRL for help.

http://www.youtube.com/watch?v=AzgmH6Zsohg

http://www.youtube.com/watch?v=fd9BD0fFuv0

Plasmas are the scourge of amateur radio.
 
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Thanks for the reply and info m42duster

Many HAMS immediately cry part 15 interfence rules. In reality. harmful interference from part 15 devices do have allowable distance and microvolt signal levels. If the offending device is very close, like the next room away in an apartment, you might have to suck it up.

Not sure what the rules are here in the UK but i do know that the licensing authority OffCom will track down and take action against interference but where you stand with a plasma TV I don't know. And there TV is very close in fact it's on the same wall as my shack (back to back) but i don't know if it's just there's or several as the noise never goes away, I have checked between 6.00 and 24.00 Hrs so it is looking like i will have to try a noise canceller.

At least i now know it is a plasma <can not stand it> because i was not sure
 

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