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Old August 19th 08, 07:50 PM posted to rec.radio.amateur.antenna
Dave Platt Dave Platt is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 464
Default Ham or CB Antenna?

He has been getting louder and louder over
the years to the point of what I described in my earlier post about
the problem with the TV's now.

And even the very first time I approached him, I mentioned that I knew
he was broadcasting illegally, and that we all have our hobbies, but
his was interfering with mine, which at the time was home theater. He
didn't deny that he wasn't illegal, at the time, and he did lower the
power, for a while.

I've approached this guy at least 5 times in the past few yrs, and
every time he has lowered the power, for a while. Not this time,
though, and it is now out of control.


Well, I have some good news and some bad news for you.

Let's do the bad news first, OK?

As others have pointed out, it's entirely possible that your neighbor
is transmitting legally. If he has a ham license, he could be
transmitting with power levels of up to 1500 watts, in most bands, and
still be entirely within the bounds of his license.

The fact that he "didn't deny" that he was "broadcasting illegally"
isn't proof, by any means. He may simply have not wanted to get into
an argument with a neighbor who was making harsh accusations without
proof or evidence (and, sorry to say, I *am* referring to you here).

Unless you have evidence that he's transmitting without a license, or
in ways which violate whatever license he has, you don't have much
legal leverage, and probably won't be able to persuade anybody to do
anything on your behalf.

As others have pointed out... if a stereo amplifier, or loudspeaker,
or telephone starts picking up and reproducing radio transmissions,
then *this* device is defective/broken/badly-designed. This is a
condition referred to as "undesired operation" - the phone or speaker
is reacting to something (a strong RF field) which is irrelevant to
this device's normal mode of operation.

It is the position of the FCC that such "undesired operation" is a
defect in the device in question, and not the fault of a (legal) radio
transmission. It's is technically possible (and not all that
difficult) to shield and filter devices such as amplifiers and phones
so that they don't react to RF fields. Some manufacturers skimp on
this filtering and shielding, in order to save money... and if the
consumer buys such a device (rather than a more expensive, better-
designed one) then any problems which result are the responsibility of
the consumer and the device's manufacturer.

Many, many consumer electronics devices these days come with a "Part
15" label or advisory, on the device or in the manual. Part of the
wording says these devices "must not interfere" with licensed radio
services, and "must accept" interference from both licensed and
unlicensed radio services "including interference which causes
undesired operation".

That's the bad news.

Now, for the good news.

It's usually possible to add some after-market RF suppression devices
to the affected components, and greatly reduce or entirely eliminate
the interference. You can buy such devices over the counter or by
mail, and they're not expensive.

For phones, a small filter which plugs in between the phone cord and
the wall outlet will often do the trick. Plug-in DSL filters are
commonly available and will probably do the job well enough.

For loudspeakers and stereos - in most cases I've seen, the RF is
being picked up by the wires between the speaker and amplifier or
PC... the wires act as antennas, carry the RF into the amplifier
section, and the amplifier "detects" the RF by accident and converts
it to audio and amplifies it. It is often possible to entirely
eliminate such unwanted pickup by adding an interference suppressor
(a.k.a "choke" or "ferrite") to each speaker wire, right before it
enters the amplifier. The commonest variety is a "snap-on" two-part
ferrite - snap it open, wind the speaker wire through it a few times
(leaving a short stub of wire at the end), snap it closed, and
reconnect the wire to the amplifier/receiver. With amplified speakers
(computer or subwoofer), put a ferrite right at the speaker end of the
wire.

Adding ferrites to the AC power cords of the receiver, amplified
subwoofers, etc. is also a good idea.

For TV interference, you may need a "high-pass filter" connected in
the antenna line right at the TV. This will keep the strong RF signal
from your neighbor's transmitter out of the TV set's receiver.

Ferrites and filters are probably available at your local Radio Shack,
or by mailorder from quite a few suppliers.

For further information about actually solving the problem, I'd
suggest that you look at the ARRL's extensive collection of
information about this issue. Start at

http://www.arrl.org/tis/info/rfigen.html

for a table of contents and a good overview of the basic issues
involved. The "Information for neighbors of hams" page is also
worthwhile reading.

Oh... if you want to know whether your neighbor is a ham, you may be
able to find out from:

http://wireless2.fcc.gov/UlsApp/UlsS...rchLicense.jsp

Click "Amateur", then plug in your zipcode and do a search. See if
your neighbor's name comes up.

However, even if your neighbor doesn't have a ham license, and is
transmitting on CB, it's entirely possible that his transmissions
could be getting into your radio even if they were limited to legal
power... and if so, he wouldn't be under any obligation to stop
transmitting or reduce power.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
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