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[TowerTalk] Interference Problem (long)

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Subject: [TowerTalk] Interference Problem (long)
From: (Dave Hachadorian)
Date: Fri Jan 31 20:59:35 2003

On Thu, 30 Jan 2003 17:59:28 -0600 "N9EN@VOYAGER.NET" <>

> The noise is always present. It doesn't matter what the
> weather is, whether windy, rainy, snowing or clear.

This could be an important clue. Whenever I've encountered
this type of 24/7 interference, it has turned out to be
a defective lightning arrestor on a power pole. These are
extremely noisy sources, and can cause interference over
a radius of a mile or two. You need to go mobile to find
the general vicinity of the source. For starters, try tuning
your AM car radio to an unused frequency, such as 1720, and
drive around. A 2 meter rig in AM mode is even better.

> have done a little investigating and found out a few things.
> The first thing that I did was to turn off every circuit breaker
> in my house, except for the one that feeds my radio equip-
> ment. With all the other breakers turned off, the noise is
> still present, just as loud as always. My rig is not capable
> of being operated on 12 VDC so I have to leave the one
> circuit breaker on that powers the rig.

Temporarily run an extension cord to your rig from another
circuit. That way you can turn off the one breaker you haven't
tried yet.

> The next thing that I found out is that if I rotate any of my
> yagis to the direction where the wires cross the road from
> my property to the other side of the road, the noise level
> peaks when the antennas are pointed at this direction. When
> the antennas are pointed away from this location, the noise
> level drops to its lowest value.

You can get a better direction indication by turning the yagis
sideways to the noise. Yagis have a sharp null off the side.

> The third thing I did was to take a battery-powered AM
> radio and walked out to the pole in my yard where the
> wires cross the road. When I approach the pole in my yard,
> the noise level that the radio is picking up begins to get much
> louder. When the radio is placed next to the pole, it gets
> even louder still.

I think you are hearing noise variations at the micro level.
Think macro. Get in the car and drive.

> I then called the cable TV utility

If it sounds like power line noise, it probably is power line
noise. I would turn my focus away from the cable system.

> I guess when it warms up a little, I'll try to find someone
> who has either a 2 meter rig with AM capability or a re-
> ceiver that can receive the AM aeronautical band and
> try to use a 2-element yagi to try to pinpoint the location
> of the noise.

That's the way to go. You can even start with the car radio
on 1720 kHz. If you can find even the general vicinity of
the source, then the power company should be able to zero in on
the defective device. 

Try also the rfi reflector,

Dave Hachadorian, K6LL
Yuma, AZ

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