Perhaps you should try wrapping the wires going in and out of each intercom
unit around ferrite beads (chokes)? I assume the communication wires are
thin so you could wrap many turns around each bead. If the wires are
already going somewhere you will have to wrap the slack around a split bead
(since you can't disconnect the wire). Palomar Engineers sells ferrite
beads. RF Parts is another source. I like the RF Parts split beads and the
Palomar rings. I think the addresses are www.palomarengineers.com and
www.rfparts.com. These get rid of (or attenuate) rf travelling on the audio
wires and also ac lines gg into the units. Of course if something is
rectifying your sig. inside the intercoms these won't help.
You don't say if you are interferring with things in your own home. If you
are, then you may have to solve some station problems. You may need a balun
at your feedpoint, a common mode filter and low pass filter at your linear;
you may need to get rid of some ground loops and improve your shack ground
or run the linear into a transmatch (even if you don't need it, it's an
extra tank circuit that will attenuate harmonics below the cutoff on the low
pass filter).
73,
Rob Atkinson
K5UJ
k5uj@hotmail.com
----Original Message Follows----
From: "kb4tcu" <kb4tcu@accessatc.net>
Reply-To: "kb4tcu" <kb4tcu@accessatc.net>
To: <rfi@contesting.com>
Subject: [RFI] M&S Systems intercom RFI where to start
To: <rfi@contesting.com>
Date: Fri, 31 May 2002 01:30:07 -0400
Seeking Help,
I recently got my station on the Air. After a few nights of operating on
the 75 meter band with output around 900watts. My next-door neighbor
informed me I was causing interferance to his M&S systems model 602
intercom.
http://www.mssystems.com/downloads.cfm?file=115755d.pdf install diagram
for the offending unit MC 602
He is not argumentative.My neighbor, while allowing me to to try to
alleviate the problem, He is the curious type. I would like to make some
progress on my first attempts. Today I hooked up my Uhf remote link to Hf
allowing me to transmit inside my neighbors home. The audio from the
interferance my station is causing is showing up on all stations. The audio
level is very low. My neighbor listens to the intercom in his bedroom in the
monitor mode. This allows him to listen to his son's room across the house.
As he prepares for sleep his room becomes very quiet and thus (my distorted
audio becomes audible on his room intercom station).
He is going to allow me to install some bypass caps and or rf chokes.
My station consistis of a icom 746 within alc driving a Ameritron AL 80A
feeding RG8U to a 1/2wave inverted V at 40' to the apex. The antenna has a
very good VSWR
and is 50' from the nearest componet in His intercom system. The antenna is
broadside to his home .
Need help
Victor Vickers KB4TCU
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