On Mon, 25 Apr 2005 23:24:49 -0400, "BobC"
wrote in :


"Frank Gilliland" wrote in message
.. .
On Mon, 25 Apr 2005 18:50:33 -0400, "BobC"
wrote in :

Well Jade,
That's pretty much the drill.
You have no proof that this guy is running anything illegal.

The fact that he's transmitting enough power to drive a pair of
speakers at a distance is a pretty good indication that it's a bit
more than 4 watts.

Frank, you'll need to do beter than that.
I've got a stock cobra in my pickup that can do this to telephones from 2
driveways away.
Stop to consider the circuitry in front of the speakers.
A high gain audio amp of dubious quality, connected to a few feet of
unshielded wire?
Easily overloaded DAC's on a sound card?
Little or no rf filtering on the hi level outputs / inputs to the sound
card?
Cheap, hi gain front ends on a scanner? (My assumption is he uses a scanner)
Gimme a break.
_________________


Ok, let's consider the circuitry in front of the speakers: Assuming
the speakers do not have their own power amps, the amps are enclosed
in a fully (or almost fully) shielded case. The only unshielded lines
into the case are pairs; i.e, only common mode currents can enter the
case. Excluding the power line (filtered by the power supply) and the
phone line (filtered by the modem transformer), the only means of
entry is through the speaker wires connected to a very low impedance
power amp. And assuming the power amp uses feedback (and that
rectification of the RF occurs at the power amp stage), it would take
just as much power to distort the amps' intended output (and therefore
cause audio feedback of the demodulated RF) as it would to drive the
speakers directly. That also assumes an efficient antenna -- resonant
lengths of speaker wire.

Now if the speakers are amplified externally (amp in the speakers),
they are more than likely driven by a shielded cable. Regardless,
almost all low-level preamps are designed for high common-mode
rejection (we're talking 60-90 dB+ at each stage); and since the low
impedance of the power amp is no less suseptible to RFI than if the
amp was enclosed in the computer case, it would -still- take a
considerable amount of RF power on the lines to drive the speakers.

This is not just theory but fact -- they are designed this way for the
specific purpose of eliminating that annoying AC hum and digital RFI
that permeates most houses, -especially- the horrific noise generated
by computer monitors and light dimmers. "Overloaded DAC's"? I don't
think so, Bob. How do you overload a DAC? YOU will have to do better
than THAT.


You might keep saying it, but that doesn't make it true.
You have the obligation to ensure your consumer electronics are not at
fault.

Only if the station is operating legally.

It's the other way around chief.
You make sure the consumer devices are protected first.
Those devices must accept interference from licensed transmitters.
And yes, even cb's are licensed to transmit even though an operator's
license is not required.
__________________


Authorization to transmit with a CB is automatically revoked when the
station is operating illegally. Shall I cite the code?


That means adding whatever filtering is needed on your end.
If adding the proper filtering doesn't fix things, then you might have an
issue.
The Fed's already know all about cheap, unfiltered consumer gear.
When you call them, they'll make you aware of it.


The Feds also know about cheap, unfiltered, Class-C "linears".

Which is all well and good but until you've satisfied the feds that
your consumer grade stuff is properly filtered, they aren't going to bother
sending anyone out to check.
_________________


They won't send anyone out regardless. They don't care about the CB.
But they do suck up to the ham community, and if it turns out that
this guy has a license they may indeed take action if they find he is
operating illegally (i.e, using power on the CB).


Your Dell & speakers are not filtered for this interference.
This goes for your scanner, your toaster and whatever else.

Get your act together and then go after whomever.
Before you can even get someone else involved, they're going to
ask if you applied the correct filtering first. If not, they'll advise you
to
do so and call them back if it doesn't work.

Those are your rights.
Now stop whining & do your part.


Quit making excuses for irresponsible CBers.

Right after holier than thou, know-it-all's step down from their hi horses
& get a grip on reality.
____________________
So far, I've not read from Jade anything that remotely suggests he or she
has
a serious interference complaint involving another radio service. I read
"fire service"
radio and I invited Jade to tell me what he/she considers a fire service
radio.
Scanners don't count.


Actually, they do. If someone is causing interference to a scanner,
it's very possible..... nay, -likely-..... that he will also cause
interference to an emergency service radio that happens to be in close
proximity. This is a problem because while the cops chase the killer
with the gun running through the neighborhood, Andy the Amphead keys
up and the guy gets away (or worse) because the cops lose comm.


I haven't seen any real proof that the neighbor is running an illegal
station.
Jade has not indicated other neighbors are complaining of similar events.
Such complaints might induce me to think the cb'er is running power.


Then that would be a good question to ask. So ask it.


Unless or until someone brings more convincing proof of the allegations,
I'm going with the notion it's a singular complaint due the quality of the
consumer electronics invloved.

You'll excuse me if I happen to believe in "reasonable doubt" &
"due process" instead of conjecture & unfounded finger pointing.
bc


How about "civic responsibility"?





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