Well, I didn't see loops mentioned, and, there is a chapter on those in the
ARRL antenna books too.
And I don't mean full-wave loops necessarily either, as I use a 1/4 wave
vertical loop on 160 m meters (it functions as a 1/2 wave loop on 80m and FW
loop on 40m) about 20 feet from the house and the PC speakers do not bark like
they do with a dipole over the house on any band.
"Open frame" antenna s like OCF and dipoles are notorious for E-field
induction of displacement currents into anything nearby from the high voltages
appearing at each open end.
de Jim WB5WPA
From: Stan Zawrotny <k4sbz.stan@gmail.com>
To: Wes Attaway (N5WA) <wesattaway@bellsouth.net>
Cc: "<Rfi@contesting.com>" <rfi@contesting.com>
Sent: Friday, July 27, 2018 3:17 PM
Subject: Re: [RFI] Smoke Detectors Beeping
Wes,
I am aware of my options for antennas - fan dipoles, slopers, G5RV, EFHW
antennas, etc. - some with less RFI, but I choose OCF dipoles for their
performance.
I think I have read almost every article and blog written on-line about
feed systems. I am getting desperate.
Thanks for your recommendation for the BRK, Model 41208. I will check
them out.
Stan
___________________
Stan Zawrotny, K4SBZ
K4SBZ.Stan@Gmail.com
Real radio bounces off the sky.
On Fri, Jul 27, 2018 at 2:19 PM, Wes Attaway (N5WA) <
wesattaway@bellsouth.net> wrote:
> 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@contesting.com] On Behalf Of Stan Zawrotny
> Sent: Friday, July 27, 2018 12:50 PM
> To: <Rfi@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@Gmail.com
>
> Real radio bounces off the sky.
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
>
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