[RFI] Smoke Detectors Beeping

[Wes Attaway (N5WA)]

Stan .... you will probably get a lot of different responses.  Here is one.

I use some smoke detectors made by BRK, Model 41208.  I think I bought them
at Home Depot.  They have never shown any sign of being susceptible to RFI.

I use two OCF antennas.  One is 40-10 and the other is 80-10).  The
impedance of OCFs is nominally around 200-ohms and the usual practice is to
use a 4:1 balun at the feedpoint to get close to a match with 50-ohm
feedline.  I also use a 1:1 choke just below the 4:1 balun and another
inside the shack.  The chokes are 17-turns of RG8X cross-wound on FT-43 2.5"
core.  I have never experienced any RFI anywhere in the house (my shack is
in my office inside the house).

Fan dipoles are popular and are probably better than OCFs but they have
their own set of mechanical and installation problems.  I use OCFs because
the fit the tree layout in my yard, whereas fan dipoles won't fit without
cutting down some trees.

In any event, I think you should change your feed system.  There are plenty
of articles online about this.


   -------------------
Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
AttawayForensics.com
   -------------------
-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Stan Zawrotny
Sent: Friday, July 27, 2018 12:50 PM
To: <Rfi at contesting.com>
Subject: [RFI] Smoke Detectors Beeping

I have been troubled for quite some time with our smoke detectors
frequently beeping (two beeps) when I am working HF. It is worst on 80 and
40, but also occurs frequently when I am on 15 and 20 meters.  The beeping
will be intermittent at intervals of 1-3 minutes and will last for a couple
of minutes after I am through transmitting.

I has happened with several rigs. Yaesu FTdx5000, Flex-6600M and Icom
IC-7300, at power ranging normally from 50-100 watts.

Of course, the antenna system is likely the culprit. It consists of several
OCF dipoles: one 160-10 M and two 80-10 M. (I know OCF dipoles are bad for
RFI). All have 1:1 baluns at the antenna and at the shack.

I have tried clip-on ferrite beads on the power leads of the smoke
detectors without luck.

I just bought a DX Engineering Feedline Current Choke (DXE-FCC050H05-B)
that is supposed to suppress RFI on antenna leads. That is ineffective.

I am now considering replacing the entire smoke detector system. We share a
house with my daughter and there are 9 units tied together in the system,
so the cost will not be small.

Are there other solutions?

Are there brands of smoke detectors that are less susceptible to RFI than
others.

Any other thoughts?

Stan
___________________
Stan Zawrotny, K4SBZ
K4SBZ.Stan at Gmail.com

Real radio bounces off the sky.
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