My neighbor, and good friend (he's not mad at me), says he can hear my code
transmissions on all the phones in his house, including the cordless ones.
No one in my house, on the other hand, can ever hear my transmissions. I
have my phones on a traditional phone line while my neighbor gets his phone
service through his television (buried coax) cable.... Any ideas?

Thanks, Pete

My neighbor, and good friend (he's not mad at me), says he can hear my code
transmissions on all the phones in his house, including the cordless ones.
No one in my house, on the other hand, can ever hear my transmissions. I
have my phones on a traditional phone line while my neighbor gets his phone
service through his television (buried coax) cable.... Any ideas?

My recollection is that cable-TV-based phone service is usually
implemented via digital cable techniques (voice-over-IP or something
similar). It becomes analog when it reaches the house (at the
cablemodem or MPOE) and is distributed over the house telephone wiring
from there.

So, the interference is probably not on the cable side itself.

There might be a couple of ways that the audio could be showing up in
his phones:

- Fundamental overload - each individual phone is reacting to the
high RF voltage levels, and is detecting the RF into audio directly.

- Interface problem - the RF is being detected into audio at one
vulnerable location, and the resulting audio is being distributed
on the phone wiring along with the normal audio of the phone
conversation.

Since your neighbor reports that it's occurring on all of the phones
(including the wireless) I tend to suspect the latter. I'd suspect
the cable-company-provided phone interface... it's probably picking up
the RF floating around on the in-house phone wiring and rectifying it
in its analog electronics.

The remedy I'd suggest is the usual one for telephone RFI - start
adding ferrites and other interference suppressors. I'd probably
start out with a bunch of the little RJ-11 plug-in RFI filters (sold
for this purpose, and also to keep DSL signals out of peoples'
phones). Start by installing one where the house phone line connects
to the cable interface. I'd also suggest getting a ferrite split core
or toroid, and winding the phone wire through it a half-dozen times as
close to the cable interface as possible.

Also, add a ferrite to the cable interface's power supply wire (again,
as close to the interface as possible) and clamp one or more ferrites
onto the TV cable itself.

By keeping your RF out of the cable/phone interface I have a feeling
that you'll probably reduce the problem quite a lot and may eliminate
it entirely.

Adding additional plug-in RFI suppressors and/or ferrite cores to the
wires on the other phones in the household may also help.

None of this is actually your responsibility, assuming that you're
transmitting legally within your privileges, but providing good advice
(and maybe a handful of plugins and ferrites) could be a helpful
gesture!

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Thanks, Dave, for your detailed reply -- lots of good tips. You're right,
of course. It really isn't my responsibility if the cable company is
putting out equipment that can "listen in" on my HF transmissions. I'm sure
my equipment is clean. Actually, before I go out and buy a collection of
ferrites and suppressors, I think I'll just encourage my friend to complain
to the cable company. They should be the ones fixing this.

Or, am I being naive here. Could they make more trouble for me than it's
worth even if I am "innocent."

Pete

Pete Holden wrote:
Or, am I being naive here. Could they make more trouble for me than it's
worth even if I am "innocent."

It's the 'Golden Rule' principle. The guys with the gold make the rules.
--
73, Cecil http://www.qsl.net/w5dxp



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Try the ARRL's RFI website for some ideas:

http://www.arrl.org/tis/info/rfigen.html
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
73! de Andy KC2SSB - WPYI880 (GMRS)
Beachwood, NJ USA! Grid FM29vw
http://vhfradiobuff.tripod.com

Pete,
From your point of view, the first step is to make sure
your transmitter is 'clean'. From your neighbor's point
of view the first step is to complain to the person causing
the interference, if possible. Sounds like both of you have
done that. The second step is to complain to the service
provider (cable, telephone, power, etc.), it's their
responcibility
to provide 'clean' service to the user. (That responcibility
only
extends as far as the service entrance in most cases. From
there
to the modem, TV, whatever, is usually the user's
responcibility.)
RFI isn't ~that~ unusual so the provider should know what to do
about it. If you have 'problems' with the provider, if the
provider
isn't reasonable at all, then the next step is to complain to
your state's utilities commission. It's their responcibility to
make sure the provider is doing what they are supposed to do.
In the mean time, or in addition to what the provider does,
your neighbor can install RFI devices on ~his~ portion of the
cable/power line/whatever. The 'trick' is in knowing where
'their'
portion ends and 'his' portion begins. (I'm sure the provider
will
let him know where that point is! LOL)
It 'sounds' worse than it really is, but doing things
'properly'
is one of the 'keys'. A bunch of us have 'been there, done
that'
so you're not alone. Good luck...
'Doc

Thanks, Dave, for your detailed reply -- lots of good tips. You're right,
of course. It really isn't my responsibility if the cable company is
putting out equipment that can "listen in" on my HF transmissions. I'm sure
my equipment is clean. Actually, before I go out and buy a collection of
ferrites and suppressors, I think I'll just encourage my friend to complain
to the cable company. They should be the ones fixing this.

And, if you're _exceptionally_ lucky, the cable company might actually
send out a tech who has the necessary amount of Clue in his van to
diagnose and fix it correctly.

I'll keep my fingers crossed for you.

Or, am I being naive here. Could they make more trouble for me than it's
worth even if I am "innocent."

Their equipment is almost certainly bearing a Part 15 certification,
which means that they don't have a leg to stand on... it "may not
interfere" with licensed radio services and "must accept" any
interference from same.

One additional thing I'd suggest: have your neighbor disconnect all
of his "inside" wiring from the cable/phone adapter, and plug a single
phone directly into the adapter. Ideally, use an old-style
non-electronic desk phone. Then, have him make a call, and try keying
down CW. If he still hears interference on the line, then the adapter
is certainly responsible.

In this case, he can use the magic words with the cable company:
"Interference is present at the demarc, with all inside wiring
disconnected." Legally, that means "It's your problem, come fix it!"

If the problem is present only when the house wiring is connected, the
issue may be a bit more sticky. It's still not _your_ fault (as the
radio operator), but there may be a question as to whether the fault
lies in the cable-company equipment (which is their responsibility) or
in the house wiring or equipment. Unfortunately, I suspect that the
basic fault lies in the cable equipment, but may only show up when the
inside wiring is connected because the inside wiring is acting as an
antenna. If your neighbor isn't paying for "inside wiring" service -
if he "owns" the inside wiring - then the cable company may try to
argue (lamely) that paying for the repair is his problem.

On the other hand, the cable company may know about the problem in
their equipment (from other cases) and may be willing to fix or
mitigate it without complaint. No way to know for sure unless you
(and he) make the call and try.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Wow... Lot's of good advice here. Thank you all.

Pete