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Author Topic: Strange noise issues, anyone else have this?  (Read 736 times)
WB4IUY
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« on: January 28, 2009, 03:10:24 PM »

Ths first problem was easy...power line noise popped up. I poked around the area and identified 4 poles. I had the local EMC come out and fix problems on 4 poles, and that helped. Great guys, and were quick to help!

Now I have a cluster of 3 spurs that appear every 60khz, from below the AM broadcast band, through 10 meters (strongest from 160-20). The spurs have a stronger center frequency, and a spur on either side of it +/- 6khz of lesser amplitude. I've been all over the area and can't find it...still looking. Anyone see this sort of problem (3 spurs, 6khz apart, every 60khz) before?

Lastly, I have a wideband noise that brings the baseline on the IC-756 scope up quite a bit from the direction of NW (around 310 or so degrees), and seems to be constant now, all day, all night. Still looking for that one, too.

Dave WB4IUY
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WB4IUY
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« Reply #1 on: January 29, 2009, 04:04:44 PM »

Boy, I feel like one dummy-de-dum-dum... After the powerline noise was corrected, I had the wideband noise w/spurs I mentioned. I could rotate my yagis, and find it at about 330 degrees. Yet, when I loaded my Escape wih receiving gear and cruised around, I couldn't find it. I set up some portable gear, and walked NW from my QTH, still couldn't find it...couldn't even HEAR it!  

I came back to the shack, and noticed I could hear it around my home. I traced it back to a new computer, right in my own shack! I failed to follow the first rule of turning the house off first, to determine if it was local. When I killed the computer, it was beautifully quiet on HF!

It was a crappy switch-mode supply in the PC. I put torroids on the power cord and nearly killed the noise. Gonna work on it more, when I get over feeling so stupid, hehehehehe...

Dave WB4IUY
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WA9UAA
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« Reply #2 on: February 02, 2009, 01:47:49 PM »

Dave,
Thanks for being brave enough to post your experience.
73,
Rob WA9UAA
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WB4BYQ
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Posts: 179




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« Reply #3 on: February 06, 2009, 05:37:17 PM »

I feel your pain.  I have cruised the streets also.  I have found that noise will come from switching mode
battery charger on a boat, wide band noise that will move up and down the band from vcr/dvd players of the low cost type, and heating pad for a dog, the walking
tredmill across the street, and aa battery charger from
Durcell, lights around the house with loose connections, my own ht battery charger from ( MH-777plus), computer power supply that did not have the power line filter installed on the circuit board.

Walking up and down the streets during the day with my
Yeasu FT-897D with a battery and very short dipole on
a stick lay on the neighbors house power meter to find
which house the noise was coming from.  All the neighbors have been very helpfull and allowed me to install Amidon FT-240-77 cores on the power cord.  The cores fixed all the problems except the computer (better power supply), and the heating pad for the dog (ower purchase new heating pad).  I would use my truck and FT-897d to located the noise with the Hustler on the bumper.  Then I would take the resonator off, use the RF ATT on the rig to cut the signal level down, so I would have to be on top of the noise to hear it.  Use
the RF Fox Hunt ideas.  Now the bands are petty clear.
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WA3SKN
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« Reply #4 on: February 11, 2009, 10:00:38 AM »

"And yet another educational experience!"
Contratulations of finding the culprit.
73s.

-Mike.
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OLDSWAB
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« Reply #5 on: February 18, 2009, 06:22:58 PM »

Before I retired. We would have a problem show up in the office snd not just ours. We were in the copier repair business. I won't mention the name of the Copier but. When it started to warm up the fuser lamp it was a slow turn on.Sound familiar? Right , from zero hertz to 120 hertz real slow causes a lot of problems in just about everything from dictation machines to the telephones ,PA systems,etc. It is very hard to repair since the manufacture wouldn't cooperate.  We dropped that brand and went to a diffferent brand that turned the lamp on at a reduced voltage and then on full.  I know where you are commming from with noise!
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N8DV
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« Reply #6 on: February 20, 2009, 05:13:35 AM »

Boy I wish my RFI problem was that easy to find and fix. I lose the 15 meter band when the noise starts. I have located in generally to a neighbors furnace blower motor! Every time the blower motor kicks on the lines of interference comes across the waterfall (I'm using digital modes) and the noise is a buzzing sound. Not much I can do. I located it to around 4 houses near me but that's all I can do. Luckily the way the bands have been, 15 meters has not been active. Any one have any suggestions? Thanks es 73
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OLDSWAB
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« Reply #7 on: February 20, 2009, 05:19:54 PM »

I hate to say this but the problem we had with the copier is basically the same. Most of the new fans and burner blowers are runing on stepper motors. Some are D.C. motors but both are controlled by frequency.
The controller is an oscillator type circuit and can produce R.F. I'm not sure how to approch this problem.  Problem here is you may cause more harm than good.You know how some neighbors can be towards any type of communication problems that they don't think they cause. On the other hand if you can come up with a freq. trap that can be attached to the furnace, maybe you can get a patient.
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