Change the wiring of smoke detectors with ftp (foiled twisted pair)
cable. As Jim says in his paper, twisted pair cables are better
protected by RF. Have in mind that UTP (unshielded twisted pair) is good
(as twisted pair). There are UTP5, UTP6 and UTP7. Bigger number is
better. Also FTP and SFTP (shielded foiled twisted pair). The best cable
you can use is SFTP. I am sure that you will not have problems after
replacing the cabling.
73 Kostas SV1DPI
Στις 28/7/2018 06:14, ο Dave Cole (NK7Z) έγραψε:
Stan,
Add a decent. (as high an impedance as you can build), choke at the
feedpoint of the antenna right after any impedance matching device,
then add another at the point where the coax enters your home.
If you are still having issues, see if your alarm systems are tied
together to a central unit, you might want to look at that as well.
Take a look at Jim's, (K9YC), papers on suppression using chokes. See:
http://k9yc.com/publish.htm
under "Hum, buzz, and RF Interference"...
73s and thanks,
Dave (NK7Z/NNR0DC)
https://www.nk7z.net
ARRL Technical Specialist
On 07/27/2018 10:49 AM, Stan Zawrotny wrote:
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@Gmail.com
Real radio bounces off the sky.
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