[RFI] Telephone Interference - blowing out phones?

Dana Roode Dana Roode <k6nr@arrl.net>
Sat, 18 Dec 1999 22:37:39 -0800

[Originally written 12/13/99, second try at posting]

Hi all,

I've been a ham for 30 years and have only been involved in a few
interference situations.  Unfortunately, I've got one now, and I'd
like your input and ideas.

I've lived at my present location for about 11 years, without any
interference complaints (other than a odd burglar alarm case from a
house a block away).  There have been three different neighbors in the
house next door - the first two had no complaints, but the current one
does.  I received a letter from her today, after thinking things were
OK after a conversation and a visit several months ago.  At that time
the main complaint was with regard to her TV, I found a poor cable
connection, and added a toroid on the cable.  She doesn't mention TVI
in the letter, so maybe I made some progress there.

She has several complaints, but the most serious appears to be with
regards to her telephone.  She says that there is constant
interference on her phone lines, completely disrupting conversations. 
She claims that "at least three phones have been blown out in the past
year".  I don't yet know what kind of phones she means, but I will be
asking.  I had previously given her a filter for her phone, and she
says that she has contacted the phone company and paid to have filters
installed, all to no avail.

I was on 10 meters this weekend, running 400w into my vertical on my
roof, base at about 30'.  No interference to my phones or anything
else in my house.  My neighbor's house is 10 feet away from mine,
about 30' from my vertical.  My equipment is grounded to a set of 8'
copper grounding rods right outside the window; I run with a low pass
filter.  (I'm wondering if those transmitting common mode chokes are
necessary or helpful, since I don't use one).

Anyone ever hear of phones being blown out due to RFI?  If the phone
company has installed filters, what's left to try in resolving the

When I last spoke with her, she said she had problems with both
cordless and wired phones.  What are folks experiences with cordless
phones?  Are the current variety pretty sensitive to nearby
transmitters?  We have a 49mhz cordless, but don't use it enough to
know if it works when I'm transmitting.

Are there professionals out there that deal with cases like these? 
What's the best way to get good help from the phone company?

Any input on any of this will be appreciated.  Meanwhile, QRP is
looking better all the time,

    Dana Roode
    Irvine, California

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