[RFI] 160m sets off CO Detector

Scott Neader KA9FOX ka9fox at qth.com
Tue Nov 29 00:15:36 EST 2005

I have a 160m inverted vee that is about 300 feet from the house.  When I 
run 1.5kw into it, I occasionally set off our AC Powered Nighthawk CO 
Detectors in the house.  They are wired together, so when one goes off, 
they all go off.

Needless to say, the family doesn't find this humorous.  In fact, it scares 
me that the kids may think that they can ignore alarms like this.  It 
happened twice in one night until I realized what was going on.  If I keep 
it at 500 watts or so, it's fine.

I wrote to the company (Nighthawk is owned by Kidde) and they wrote back 
with the following advice:

>      I am sorry to hear about your problem.  We have heard of this problem
>and do have a solution.  Try purchasing snap on Ferrite beads.  You can get
>these from Digikey (www.digikey.com).  Place a bead on the white power cord
>of the detector as close to the detector as possible.  If your units are
>made before 2004 it would be best to replace them for maximum results.  The
>website www.arrl.org will also offer some tips.
>I hope this helps,
>William Slawter
>Kidde Safety Customer Service
>1394 South Third Street
>Mebane, NC 27302
>800-880-6788 ext. 8417

I immediately wrote back asking about this "made before 2004" business.  If 
they added or improved on the RFI supression since then, I am going to push 
hard to have them replace mine at no charge.  That is BS in my opinion, as 
we purchased them in early 2004, but indeed they were made in 2003 
(probably sat in some warehouse before I bought them).

Anyway, assuming I don't get any satisfaction from Nighthawk/Kidde, can 
someone recommend a specific type of bead given my situation?

I also did go to www.arrl.org as he suggested and tried some site searches 
but never found anything useful on searches of "RFI" and "detector".

Thanks in advance!

- Scott KA9FOX 

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