On 05/23/2010 07:05 PM, WA4VZQ wrote:
"Bill wrote in message
...
On 05/22/2010 01:40 PM, Bill M wrote:
What sort of antenna are you using? You might be able to configure
something, although I'm not exactly sure what, that can provide more
directivity and maybe escape from some of the junk noise.

I have a sort of long wire, 25 feet, and the other side is grounded to
a chain link fence. There is not enough room to put up much else unless
I run a wire to the house behind me. Yup, two rental houses on one lot.
My stepdaughter lives in the back and I don't even know if she could
figure out the concept of radio DX noise. She is a cable TV addict and
not at all inclined to radio. I do have a radio direction finder that I
can run with a solar cell I picked up, so I can walk it around in the
sun and try to find the major noise source that way. When I scoped it,
it looked like a lot of SCR's triggering at various points so I kind of
figure it may be SCR light dimmers.

I think I will get my RDF and go hunting tomorrow.
Thanks,
Bill Baka

To add to what Scott Dorsey said, the chain link fence may be a problem
in itself. The zinc galvanizing protects the steel below from rusting,
but it provides a nonlinear junction with any other metals touching it,
especially copper. Your radio needs a good ground with the shortest
ground lead possible. Get a good copper-clad ground rod at the home
improvement store. Locate it below the window closest the radio and run
a short, heavy gauge wire from it to the radio. Your radio should also
be grounded to the power line ground for safety.

Good advice but this house is old and does not have a third wire ground
line. There is one at the junction box, but only two lead wire feeding
the house. It may be time to sink a ground rod under my window.

The preamp must be very linear and have an exceptionally high dynamic
range to not cause problems. If it does not, RF interference at one
frequency will mix with all other signals to produce a cacophony of
noise. Your receiver should be more than sensitive enough on the lower
bands to not need a preamp. If you must use it on the higher bands,
consider using a high-pass filter ahead of the preamp. It will attenuate
the lower frequencies (where the noise is the strongest) yet allow the
higher frequencies to pass with little to no attenuation.

I try to DX on anything from 540KHz to 31 MHZ, so it is a mixed bag. The
noise waveform on the scope is the same with and without the preamp in
the loop. If it is power line I could always hook a scope probe to the
high (hot) side of the 110 VAC and take a look. I can easily build a
simple filter to take out the 60 Hz power line and just look for spikes.

The Timewave (formerly JPS) ANC-4 and the MFJ 1026 noise cancellers work
quite well if you have a single noise source or if one noise source
dominates. With multiple sources, they do not work nearly as well. For
a homebrew version, see the article by W7XC in the July, 1994 QST. Note
that there are several subsequent corrections and additions to this
article (9/1994, 1/1995, 9/1996).

I'm thinking that one of these or something I design would be synced to
the power line and just take out a piece at a time. A one shot for the
delay to the biggest noise pulse (variable by me) and another one shot
with variable width to cover the width of the noise pulse. A double
section one shot and a digital switch like a DG411 could take out the
worst pulse. Depending on my ambition I could make another few for the
next biggest pulses, but at some point all the chopping of the signal
might make the actual signal un-listenable.


Be persistent with the power company but do not get your hopes up. I
once called the power company and they sent a crew out. They listened
with their truck two-way radio and said they could not hear any noise.
Of course, the truck radio was FM! :-(

73, Barry WA4VZQ



The only thing I have ever gotten out of the power company was an extra
transformer due to overload from one transformer feeding about ten
houses, all with A/C going. They finally gave in and put in another so
that only 5 houses per transformer was the end game. I tried the noise
thing a while back and they just asked if I had power, and I said yes,
then they said 'NO'. With so few of us non-internet addicts around these
days they could care less about radio reception.
About ten years ago I located a noisy pole and told them but they did
nothing until it arced over and burned off the top of the pole. Only
then did they respond, and it was way more expensive than fixing it in
the first place would have been.
Thanks,
Bill Baka