[RFI] RF into home alarm system

Tim Duffy k3lr at k3lr.com
Sun Oct 18 21:46:47 EDT 2015

Hello Mike:

I know you may not want to hear this - but with a WIRED system and your
antennas close at 1.5 KW - you are asking for trouble - that wired system is
a huge antenna.

Wireless detectors are the only way to make sure you have a fighting chance.
I have 31 wireless doors, windows, motion, heat detect, fire detect, etc.
here at K3LR - no problems with RFI falsing what-so-ever.

Tim K3LR

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of W5JR Mike
Sent: Sunday, October 18, 2015 9:35 PM
To: rfi at contesting.com
Subject: [RFI] RF into home alarm system

As the subject line says. 

For the past two years, I've not caused any issue to our home alarm system.
The typical 4 wire JK style wire run all over the house. Lots of doors and
windows. And 13 smoke detectors. I run 1.5 kw, 160 to 10 (less on 30m) and
nary a peep. 

Last eve, wanting to play a bit in the Pre-Stew on 160m, but as yet not
having my 160 antenna repaired, I was able to get the tuner to find a match
on the 80m OCF. Even with just 100w, folks were answering my CQ's. I'm sure
there was lots of stray RF floating around. 

My wife came rushing over to the shack in a panic. It turned out the alarm
was in full on,  every annunciator sounding simultaneously. Fire, intrusion
- one big mess. I knew there wasn't a fire as the control panel told me
there was a fault condition. Nothing on the control panel would clear it.
Only by removing all power was I able to cleared it. 

Now that I've prepped you with the setup, the question is if anyone has had
to tame their alarm system to reduce its RF susceptibility and what steps
did you do to get there?

I don't expect the installer to have any useful input, nor the manufacturer,
but they may have dealt with this for a neighbor to a ham. 

I'm anticipating the recommended solution will be lots of Mix 31. Can I wind
all or several of the wires together on donuts? Am I better off using  one
on each wire (yes, still multiple turns)? Would adding bypass caps be of any

Mike / W5JR
Alpharetta GA
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