Re: belkin power conditioner for my Samsung LCD - is it worth it???

Of course coax can carry more current. But current capacity is not
relevant. That says nothing about minimal leakage to the center
conductor even with poor shielding. Disappointing is why this basic
concept is unknown here. This was discussed in many places including
rec.radio.antenna. amateur - maybe in posts from Richard Harrison. I
have long since forgotten.

Even a coax cable with minimal and leaky shielding permits minimal
current into center coax. A concept even demonstrated in a first year
EM Wave course.

Cable companies say same thing. piggy was told that a $90 belkin
was best not used. Obviously. As explained here repeatedly and made
so obvious in 1st year EM Wave course, as well as evident in
parameters in the telegrapher's equation - the coax center core is
shielded from surges outside the cable. Then cable TV cable has
better shielding. Then that cable has double layers of shielding.
Then both ends of that cable have surge protection.

If radios do not routinely contain RF amp protection, then every car
radio and cell phone in the vicinity of a lightning strike would be
destroyed. Those RF transistors can be damaged by only volts.
Therefore static electric discharges would routinely damage all radios
and TVs. Just because one radio fails (a defective design) means
routine protection does not exist?

The cable guy is correct. That $90 belkin does nothing useful. The
cable is earthed meaning that surges should not enter the building.
Anything that might leak through double layered shielding is made
further irrelevant by protection routine in RF amp circuit designs.
This protection was integrated even inside 1950 TV tuners. Then made
even better when tuners used semiconductors.

Why do cable companies now properly install (earth) that cable?
Cable must provide service equivalent to or exceeding reliability of
POTS (phone service). If that $90 belkin did something useful, then
cable company would install those same $0.10 parts. Reliability is
that necessary for the same reasons telcos install a protector at each
subscriber interface - where their wires enter a home. If
differential surges existed as assumed, then cable companies would
waste no time installing those $0.10 parts to make it irrelevant.
But that protection is already inside cable amplifiers and in
household cable appliances.

Notice how massive that profit margin on a $90 belkin. Add some
$0.10 parts and sell it for how much more? Just another reason why a
plug-in promoter will post anything here to deny technical reality.

Why do you completely ignore all car radios and cell phone destroyed
by nearby lightning strikes - zero. Zero because RF amp circuits
already include protection. I even remember it in a *** Tracey wrist
radios - a CB radio toy. Why ignore shielding even found in a poorly
shielded buried coax cable? Why ignore protectors already installed
at both ends of every coax cable? Why ignore what cable companies -
most concerned with reliability - say about that $90 belkin? Why make
claims that contradict what was even discussed in
rec.radio.antenna.amateur?

Protection is defined by a single point earth ground. Whereas other
utilities must earth every wire in every cable via a protector - a
shunt mode device - instead, cable needs no such protector.

If a coax wire terminates at an antenna where its center core
connects to exposed antenna elements, then an earthed center core
protector might be useful. But that exposure does not exist in cable
service. In cable TV service, cable center core connects to
protection even inside cable amplifiers.

On Aug 20, 11:20 pm, phil-news-nos...@xxxxxxxx wrote:
,,,
This doesn't make any sense. Coax can carry a _lot_ more current than
that. It can carry massively _huge_ amounts of current if you don't
mind destroying it in the process.
...

Voltage is important when dealing with differential mode. If a surge
is in common mode up to a point where the shield is connected solidly
to ground via a short wire, from that point on it can be mostly
differential mode. The voltage that would be developed with depend
on the current, of course. But the maximum voltage you could get is
the voltage the insulation would still hold back against a breakdown.
...

My first experience with lightning destroying a radio was when I was
about 13 years old. I was listening to a portable radio inside during
a thunderstorm. The telescoping antenna was up about 2 feet long.
A lightning strike occurred at the far end of the back yard, which was
about 80 or 90 feet away. The radio just went dead and never worked
again, other than being able to produce some hiss to the speaker at
full volume.

Such protection is not routinely in radios. I can't say there is no
radio that has it. But none of the dozen or so I have taken apart
had any.
...

Earthing only the shield of the coax and providing no other protection
is only partial protection of the coax.

BTW, I'm tiring of this repetition. We don't 100% disagree or 100%
agree. It appears we shall have to leave it at that. It takes quite
some time to post these extensive replies, and we aren't getting anywhere
at all with this.

.

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