harnessing lightning, or not

[BlindBaby]

This "reverse lightning" might possibly
be of some value if you want to harmess
atmospheric static electricity.

ALL lighting, and certainly any that you would end up capturing,
regardless of what direction it was shot or where you caught it at, is
'atmospheric static electricity', silly man.

 

[BlindBaby]

Not as BIG as a full blown strike, but
it seems that if you put up a tower
this (invisible) lightning takes place
much more frequently.

Yes. A pointed object makes for a high voltage gradient.

I have seen 'dull tipped' HV probes probe 50kV in a bath of dielectric
fluid, and arc a half inch through the fluid, to the tip, as the 'probe'
approached the HV node.

I have then seen that probe tip get changed to a sharply pointed tip,
and then seen the subsequent arc flash right through the fluid, and jump
2 inches through the air as well, to get to that 'probe tip'.

The fluid gets 'perturbed' in the first case as the tip approaches. In
the second case, it looks like an over-modulated ultrasonic bath, right
up until the arc jumps up and out of it!

 

[[email protected]]

ALL lighting, and certainly any that you would end up capturing,

^^^^^^^^
Lighting? What a putz, DimBulb.

 

[Archimedes' Lever]

G > This "reverse lightning" might possibly
G > be of some value if you want to harmess
G > atmospheric static electricity.

Archimedes' Lever 72.197.137.141 Cox Oceanside

Even your new client is lame, as is your method of quoting.

You and gmail should all take a fucking hike out of Usenet until you get
a brain on your shoulders.

AL > ALL lighting, and certainly any that you
AL > would end up capturing, regardless of
AL > what direction it was shot or where you
AL > caught it at, is 'atmospheric static electricity',
AL > silly man.

Then what are you arguing about?

Who is arguing, idiot. You stated that as if the downward firing
'type' was of some 'other' nature, not me. And the topic IS about
"harnessing" it, which infers doing work. Your remark suggests that you
think that the cloud level stuff is incapable of doing work and that the
ground strikes are capable of it. So, it is you that needs to clarify
what YOU think static is, and what you think large accumulations of it
can be used for. All that, long before you go talking about actually
storing some of it. You are the one that needs to tell us what YOUR
definition of static electricity is.
snipped link to primer that was not needed.

Beside the fact that your links carry little credence with me.

Like I said... a giant Leyden jar. That is what one ends up with.

 

[Joerg]

You rate 3 "good" answers out of 14. That site has very high
standards!

Why not use the lightning to heat water? The impedance match is
potentially better, and it's easy to store hot water. We could throw a
neighborhood hot-tub party after every strike, every 40 years or so.

We don't get lightning here. I kind of miss it.

I don't miss it, seen to much electronics come to grief from it. Hey,
why don't engineers at RF module manufacturers get it into their heads
that the first part after the antenna jack has got to be an inductor to
ground? Anything else will eventually go *PHUT*.

 

[Archimedes' Lever]

^^^^^^^^
Lighting? What a putz, DimBulb.

Why yes, you are, Williams. Mainly for bringing up an obvious typo.
Obvious to anyone that has seen any of my previous posts, where it is
spelled correctly.

Obvious to anyone with an IQ over 40. Most likely why you ruled
yourself out with your 'pussy boy wants to be in the group but isn't'
idiot mentality. Please, take your senile stupidity and go away.

 

[[email protected]]

Why yes, you are, Williams. Mainly for bringing up an obvious typo.

You're a hypocritical putz, too, DimBulb.

Obvious to anyone that has seen any of my previous posts, where it is
spelled correctly.

Then why do you insist on doing the exact same thing, AlwaysWrong?

Obvious to anyone with an IQ over 40. Most likely why you ruled
yourself out with your 'pussy boy wants to be in the group but isn't'
idiot mentality. Please, take your senile stupidity and go away.

AlwaysWrong is always wrong, as everyone here knows.

 

[Joerg]

Yawn.

T'is what I did when I just encountered the umpteenth module where that
was done wrong

 

[Joerg]

Yawn, as in: WHAT ABOUT ALL THE RF EQUIPMENT WITH A DC VOLTAGE AT THE
INPUT CONNECTOR?

Gear out in the field typically never has that. I've done a lot of RF
designs and even more re-designs by now. The number of units that would
be DC-fed or have to provide LNA power was zero. Fact is, units deployed
in the south or on the island won't even live through the first year
with a nice big inductor to ground. Lightning strike into some fence out
there, voltage surge, somewhere above 100V the input cap decides it's
had it ... *POP* ... preamp and final TX amp are goners.

Of course, if you design sat-gear that's different.

 

[Paul Keinanen]

Some filtering would be required to keep out strong out of band
signals (such as broadcasting radio and TV or radar) from overloading
the front end. The inductor to ground would come naturally as part of
a parallel LC filter.

Gear out in the field typically never has that. I've done a lot of RF
designs and even more re-designs by now. The number of units that would
be DC-fed or have to provide LNA power was zero. Fact is, units deployed
in the south or on the island won't even live through the first year
with a nice big inductor to ground. Lightning strike into some fence out
there, voltage surge, somewhere above 100V the input cap decides it's
had it ... *POP* ... preamp and final TX amp are goners.

Of course, if you design sat-gear that's different.

With microwave gears, in the cavity resonator, use a magnetic probe
(not capacitive probe) to connect to the amplifier input, since the
other end of the magnetic probe is connected to the case.

 

[Joerg]

Some filtering would be required to keep out strong out of band
signals (such as broadcasting radio and TV or radar) from overloading
the front end. The inductor to ground would come naturally as part of
a parallel LC filter.

Most of this stuff is nowadays wideband so you'll find low/highpass
combos. Or sometimes nothing. Lightning typically has most of its
spectral energy under 1MHz. Easy to muffle but many if not most
designers of RF module fail to do so.

[...]

 

[Joerg]

If they won't survive, why are there hundreds of Dish and Direct
satellite companies around here? Or line powered TV preamps? The only
RF equipment I've lost was due to a direct strike that scatter pieces of
the amplified TV antenna over about 1000 square feet. This is the
highest lightning strike are in the US.

Because the LNAs protect them by dying in their place

I've had a 5 meter sat dish hit by lightning. I lost all of the LNAs,
but not one sat receiver. The biggest risk is poorly grounded systems.
Its amazing to see MATV or other head ends and equipment rooms with a
piece of 14 gauge wire looped around the room and connected to an
outlet. Then they think they are protected. You need a good, heavy
duty rack and a good grounding system. One head end ended up with a
ground rod for each rack, and bare 8 AWG solid copper wire. All of
antenna lines were rerouted to a 1/4" aluminum ground plane. It was
tied to the new grounding system. From what I heard, they never had
problems from lightning again, even though the tower has been struck
several times.

When I was repairing CATV headend equipment it was amazing how poorly
designed some equipment was. The best had a rf transformer at the input
for isolation. Some didn't even have a resistor across the input
connector to bleed off a static charge. The typical value was around
4.7K.

See? That's the stuff I also find and I bet your experience is more than
a decade ago. That would mean in a decade or more almost nothing has
been learned about lightning effects. What really irks me is that they
still don't seem to teach this sort of practical stuff at universities.

Another problem was thin steel chassis, held together by sheet metal
screws. The spot welded aluminum cases were better, and used PEM nuts
to secure the cover. The heavy case had a lot lower impedance to ground
than the cheap steel cases.

I usually have to deal with <gasp> PVC or ABS :-(

 

[Spehro Pefhany]

If they won't survive, why are there hundreds of Dish and Direct
satellite companies around here? Or line powered TV preamps?

Active antennas (powered through the signal coax) are quite common on
aircraft navigation systems too, so splitters etc. have to be
specified with some care.

 

[Archimedes' Lever]

Active antennas (powered through the signal coax) are quite common on
aircraft navigation systems too, so splitters etc. have to be
specified with some care.

They are usually NOT exposed. ie under a sheath, nosecone, or dome.

 

[Joerg]

They are usually NOT exposed. ie under a sheath, nosecone, or dome.

How's that going to help against lightning effects?

 

[Archimedes' Lever]

How's that going to help against lightning effects?

An antenna under a dome or sheath will not be an attractor for
lightning like a raw, exposed stick would, so the strike will be upon the
craft, not the antenna. The only effect after that are the induced EM
effects, if any.

 

[Joerg]

What are they going to teach? It costs money to design hardened
equipment, and some bean counter is always saying NO!!! Companies that
are good at building hardened equipment treat there methods as
proprietary information.

Nowadays an inductor can be had for 2-3 cents. At least in China. Most
of the time the cost change is zero because all you need to do is swing
a filter architecture for T to Pi. Same number of parts but no more
phhhht ... *POP*. Bean counters really like that

Sorry, but I don't work with crap.

There are applications where plastic isn't crap at all. Or do you think
radio-translucent dome caps on aircraft are crap?

 

[Joerg]

An antenna under a dome or sheath will not be an attractor for
lightning like a raw, exposed stick would, so the strike will be upon the
craft, not the antenna. The only effect after that are the induced EM
effects, if any.

It is not about a direct strike, it is about coupled voltage spikes from
strikes in the vicinity. If you don't have a conductive path right from
antenna to GND that typically means more field failures. A lot more.

 

[Spehro Pefhany]

An antenna under a dome or sheath will not be an attractor for
lightning like a raw, exposed stick would, so the strike will be upon the
craft, not the antenna. The only effect after that are the induced EM
effects, if any.

Not much of a "stick" at L1, L2, or the frequencies used by the
geostationary sats for WAAS, as well as sat data/voice (eg. Iridium).

 

[Archimedes' Lever]

It is not about a direct strike, it is about coupled voltage spikes from
strikes in the vicinity. If you don't have a conductive path right from
antenna to GND that typically means more field failures. A lot more.

What part of the word 'induced' did you fail to learn in your study
years?