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Re: [RFI] Non-transmitting tower causes RFI/EMI?

To: n6cy@earthlink.net
Subject: Re: [RFI] Non-transmitting tower causes RFI/EMI?
From: "Larry Benko, W0QE" <xxw0qe@comcast.net>
Date: Wed, 14 Nov 2007 07:44:38 -0700
List-post: <mailto:rfi@contesting.com>

Since the neighbor is not too cooperative I would try a different 
approach. Why not go to the store and buy the exact same model as your 
neighbor has and put it in your house.  I  believe this model is a 2 
wire AC powered (no ground connection) detector with no other 
connections to anything.  If this is not correct then the following does 
not apply.

Perhaps it will work properly but if not I would put a AC line filter in 
front of it such as one of the TrippLite units which has both common 
mode and differential filtering and see if that fixes the false alarms.  
If it does I would then try an AC rated capacitor across the AC line 
with a value of .047uF or .01uF.  A device which has no connection other 
than the AC is probably not suffering from any common mode current 
issues since there is no place for this current to go.  The capacitor 
across the line will help differential noise issues.

I have an old AC powered CO detector which never gave false alarms 
unless I was transmitting.  After mounting the capacitor inside the unit 
right at where the AC connects it has never complained since.  If this 
fixed your unit, you then could say to your neighbor that his unit must 
be defective and that you would give him your unit (fixed of course) 
since you are such a nice guy.

Good luck,
73, Larry  W0QE

Rick Low wrote:
> 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
> false alarms.
> 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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