First, I have found the units that are powered by the AC line to be
triggered by stuff on the AC line. For example, other appliances that draw
heavy currents and may have a connection going bad. Unfortunately that also
includes RF which more likely caused by any 'wire dipole band' operation (40
& 80) as opposed to the stuff on your beam (20-15-10). You can continue to
do all kinds of searching for other stuff on the bands but I sincerely doubt
that is the problem or you could/would be facing the same issues.
Unfortunately, this issue will quickly become, if not there already, an
emotional issue and facts and scientific methods will not find much
acceptance by the neighbor. You need to resolve this quickly and in a
manner he/she can clearly see.
That said, I would get a detector that operates on a 9 volt battery and take
it over to the neighbors house and ask him to place the battery unit right
next to the AC powered unit. Explain to him how prone the AC powered units
are to interference of ALL types. It might even be he has an appliance that
has a connection going bad and making a lot of noise on the electric line.
The battery powered unit will not have that problem and that is why he is to
compare the two side by side. Then have him watch and see how the two units
compare. If they both go off, ask him to record the times. If just his goes
off, you have a pretty good demo the problem is the AC powered (junky) unit.
I think it goes without saying that you should also carefully log when you
are on the air.
Finally, if both units go off at the same time and you are not on the air,
he has a Carbon Monoxide problem that he needs to solve!! Gas water heaters
are an unsuspecting source as they randomly come on and off. You indicated
this has been happening for 18 months so it is likely not a furnace or gas
Good luck and keep it simple. Science may explain the problem but the
neighbor will never accept it is his problem until you dramatically show
From: firstname.lastname@example.org [mailto:email@example.com] On
Behalf Of Rick Low
Sent: Tuesday, November 13, 2007 8:48 PM
Subject: [RFI] Non-transmitting tower causes RFI/EMI?
For the past year and a half my neighbor has claimed frequent interference
to his Kidde "Nighthawk" Carbon Monoxide detectors. While we've been able to
prove a few frequency/power combinations that definitely result in false
alarms, a majority of the "alarms" occur when I'm not transmitting at all!
The neighbor's claim is that my tower (and by extension, the yagi on it) is
somehow 'reflecting' another signal in the neighborhood and causing the
I've tried to explain the implausibility of the claim, and even tuned
through the HF spectrum during some of these false alarms, without finding
any signals that to me would obviously be strong enough to cause them. But
the belief remains in my neighbors' mind that I am the cause of the abnormal
occurrences in their house. My house is experiencing zero false alarms
during the same period.
So the question for the community: Is my neighbors' claim valid? How might I
go about helping to prove (or disprove) it?
Many thanks for your candid thoughts. 73 Rick N6CY/4
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