[RFI] Smoke-alarm Interference - not TVI but SAI

Mike Ryan mryan001 at tampabay.rr.com
Wed Oct 22 10:47:16 EDT 2014

I don't know anything about your issue with the smoke alarms but just after 
I moved to Florida and set up my station, I began getting into my next door 
neighbor's alarm when it was turned on.  ANY amount of HF rf would set it 
off.  I discussed this with a friend lives in Virginia where I had just 
moved from. We did a few tests and it appeared that the problem could be 
solved by putting bypass caps at the ends of the leads to the KEY PADS 
located just inside the front door, inside the laundry room off the garage, 
and on the master control box leads to the sensors.  This worked and I have 
never had a problem since.  If the issue is with some kind of a wireless 
system, the results may vary or the fix might not work at all. But it did 
here.  '73, -Mike

-----Original Message----- 
From: Kenneth G. Gordon
Sent: Monday, October 20, 2014 8:35 PM
To: RFI at contesting.com
Subject: [RFI] Smoke-alarm Interference - not TVI but SAI

OK, Folks, I can use some help here, not for me, personally, but for some
fellows on another forum (600 Meter Research Group) who are having
problems getting into hard-wired smoke-alarms.

Their frequency of operation is at or near 500 KHz. One fellow is setting 
his own smoke-alarms, and another fellow is getting into a particularly
difficult neighbor's alarms.

The second fellow's neighbors called the FCC and complained to them. The
FCC contacted the ham, and when they were told what and how he was
operating, they told the neighbors to go to Radio Shack and buy some
filters....which didn't particularly satisfy the neighbors.

Anyway, might you people have some suggestions as to solutions for this
problem? What sorts of filters would work to keep from setting off the
smoke-alarms? The only really effective one I can think of is an ax...

(Why must we be constantly plagued by this sort of crap, anyway?)


Ken Gordon W7EKB
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