Telephone RFI Help Summary
Ocker at KD5PJ.dseg.ti.com
Thu Aug 19 09:45:41 EDT 1993
First of all, I would like to thank all who responded. Your suggestions
and ideas are greatly appreciated.
The RFI problem has been cured. It was not as bad as I thought. I took
the time to read and digest all the responses, especially the ARRL RFI
info packet (tnx KA1CV and all at the League).
I originally had the ICE filters mounted on the wall face plates, which
meant there was a length of cable (read: antennna) going to the
telephone. Moving the ICE filters to the base of the telephone (tnx
N6TV for the suggestion) fixed the problem.
However, another problem arose. My wife complained about the rfi filter
mounted on the telephone. I had to agree. It really didn't fit well
and looked cluttered. I decided to remove the filters and instead try
wrapping 7 or 8 turns of the telephone cable through a toroid, making
sure that the toroid was as close to the telephone as possible.
It worked. Even with the answering machine in line.
What did I learn? Biggest lesson was to keep it simple. Second lesson
was the distinction between differential-mode and common-mode
propagation paths of unwanted junk. Wrapping the cord through the
toroid created a common-mode choke. Case solved.
For anyone else out there who is wrestling with these problems, a good
place to start is to arm yourself with as much information as possible.
A great place for that is the ARRL. They have an Automated Mail Server
(info at arrl.org) and can e-mail you the EMI/RFI Package courtesy of their
Technical Information Service.
Once again, thanks to all for helping with what I thought was going to
be a real pain in the rear but turned out to be a piece of cake.
73 es CUL,
Charlie KD5PJ ocker at kd5pj.dseg.ti.com
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