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Author Topic: noise problem  (Read 757 times)
WB0MNW
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Posts: 15




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« on: August 28, 2007, 01:36:18 PM »

I was going to attach a .wav file with the noise I’m experiencing but I can't seem to get it done. The noise comes and goes with the heat of the day.  It’ll be quiet in the morning but as the heat builds up the noise will pop in and out until finally stays in. In the evening as it cools, the noise will drop out and then back in until it goes away for the night. During a night when it does not cool down the noise will be there all night. If the high for the day doesn’t get above 80, the noise will not be there at all. The worst is on 20 but also on 17, 15 and somewhat on 10. I use a Yaesu FT-747GX. I have operated it on battery power and killed the service to the house but the noise is still there. I use a vertical and a tri-bander with the noise on both of them. I can lower the noise by a couple of  S units by rotating the beam so there is a directional aspect to the noise. When the noise starts in the morning it will be S 5 but increase to S 9+ by midday.
It may be commercial power related as our town suffered a severe ice storm in January with much of the power infrastructure requiring a rebuild but I‘m not sure. If it is a power problem how would one begin to track the source down?
Any help or ideas will be greatly appreciated.
Bob
WBØMNW


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KE3WD
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Posts: 5689




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« Reply #1 on: August 28, 2007, 04:06:48 PM »

Sounds like somebody's air conditioner.  

See if you can hear the same noise on an AM receiver.  

If you can, then find the lowest freq. on the AM radio that you can hear the noise, use its loopstick antenna as a direction finder, odds are good that the offending thing is close to you somewhere.  

Also, see if you can pick it up on the AM radio in the car or truck, then you can drive around and locate the area where to get out with the portable AM receiver.


.
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K1CJS
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Posts: 6055




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« Reply #2 on: September 04, 2007, 07:00:10 AM »

From your description, it is temperature related--but without being able to hear the noise it is hard to tell what it may be.  It may be an air conditioner, but I doubt it because that noise would usually hold to a certain level and not increase or decrease depending on the temperature.

From your descriptions, it may be something to do with the extra power being drawn from the power grid when the temperature goes up.  It could be in a substation or a grid monitoring point if the power grid in your area uses them.  The monitor is a pole mounted device with a radio antenna above it.

Another place to look is a factory or business that uses temperature dependent manufacturing techniques.  It could be in the controls or equipment for an industrial refrigeration unit, or a water pumping station.

The AM radio detection method discussed is the best way to find the problem.  Good luck!  
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WB0MNW
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Posts: 15




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« Reply #3 on: September 06, 2007, 08:11:08 AM »

Thanks all for the ideas. I'm sure I'll find the problem eventually.
73's,
Bob
WBØMNW
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N1UK
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Posts: 1572




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« Reply #4 on: September 20, 2007, 12:25:09 PM »

Is it the noise coming from the power lines. I have/had power line noise and it starts in the afternoons as it get's hotter and goes away in the evenings. In my case I believe it was the metal pins that hold the insulators together in a row. The new insulators are one piece and don't have this problem. The power company have been very good and recently replaced the insulators on the pole near my hoise. The noise doesn't occur on wet days as the water tends to short the small arc gap on the insulator pins


Mark N1UK G3ZZM
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