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Old June 28th 06, 03:27 PM posted to rec.radio.amateur.antenna
chuck
 
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gravity wrote:
"Cecil Moore" wrote in message
y.net...
Gene Fuller wrote:
How do you know there is no corona discharge?

Because under passive fairweather conditions, corona
requires 13 magnitudes more current than is available
in nature. Please see my other posting.

And just a comment on your seeming innocent question
above. You seem to be asking me to prove that there
is no corona discharge when proving a negative is
impossible. The onus of proof is upon the one(s) who
assert(s) the positive position.

W8JI asserted that there is a corona discharge and
you agreed with him. Therefore, the onus of proof
is upon you. Please prove that corona can exist
on a receiving antenna under passive fairweather
conditions.

People are free to assert negatives at any time
without any proof. For instance, if I assert that
you cannot dunk a basketball, my assertion will
remain true until you prove that you can dunk
a basketball.


you can restate most negatives as positives. an example of this is a
logical statement, in which case the contrapositive is always true. if P,
then Q. if not Q, then not P.


Afraid you have this wrong, gravity.

Consider:

P=today is my birthday
Q=I will receive a present

If (today is my birthday) then (I will
receive a present).

If (I will receive a present) then MAYBE
today is my birthday and MAYBE it is not.

73,

Chuck


another example is Demorgan's theorem in set
theory and electronics.

if you say that general relativity is wrong, the burden is on you to prove
otherwise.

if the corona discharge theory is held by 90% of physicists and engineers,
then anyone with a charged particle theory (a minority viewpoint) must do
experimental verification or formulate a theoretical model.

in this case, i think that both Cecil and others should cite peer reviewed
articles.

Gravity



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Old June 28th 06, 03:39 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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chuck wrote:
If (I will receive a present) then MAYBE today is my birthday and MAYBE
it is not.


Expanding:

"If I receive a present today, then today is my birthday."

Assuming no present is received today, that statement is
true by definition. :-)
--
73, Cecil http://www.qsl.net/w5dxp
  #353   Report Post  
Old June 28th 06, 03:49 PM posted to rec.radio.amateur.antenna
chuck
 
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Cecil Moore wrote:
chuck wrote:
If (I will receive a present) then MAYBE today is my birthday and
MAYBE it is not.


Expanding:

"If I receive a present today, then today is my birthday."

Assuming no present is received today, that statement is
true by definition. :-)


Sorry, Cecil. I'm not following you on that.

Whether the statement P implies Q is
true has nothing to do with whether P is
true.

My point was that P implies Q does NOT
mean if ~Q then not ~P.

73,

Chuck

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Old June 28th 06, 04:25 PM posted to rec.radio.amateur.antenna
chuck
 
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chuck wrote:


My point was that P implies Q does NOT mean if ~Q then not ~P.




Well, I screwed up again.

Of course it does.

Mixed up converse and contrapositive and
sorry for the diversion.

73,

Chuck

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Old June 28th 06, 06:42 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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chuck wrote:
Cecil Moore wrote:
"If I receive a present today, then today is my birthday."

Assuming no present is received today, that statement is
true by definition. :-)


Sorry, Cecil. I'm not following you on that.


Neither do a lot of other people. Here's the truth table
for an: (If A then B) = C logical statement

A B C

True True True
True False False
False True True
False False True

If the if-portion of an if/then statement is false,
then the entire statement is true, by definition.

For instance, this is a logically true statement.

If I were ever to play in the NBA, then I would be a superstar.

Since the A portion can never be true, the entire statement
is true, by definition.

In your earlier example, *both of these statements are true*
if you didn't receive a present. Only if you actually received
a present can one be true and the other false.

1. If I receive a present, it's my birthday.
2. If I receive a present, it's not my birthday.
--
73, Cecil http://www.qsl.net/w5dxp


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Old June 28th 06, 06:53 PM posted to rec.radio.amateur.antenna
gravity
 
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"chuck" wrote in message
...

you can restate most negatives as positives. an example of this is a
logical statement, in which case the contrapositive is always true. if

P,
then Q. if not Q, then not P.


Afraid you have this wrong, gravity.

Consider:

P=today is my birthday
Q=I will receive a present

If (today is my birthday) then (I will
receive a present).

If (I will receive a present) then MAYBE
today is my birthday and MAYBE it is not.


that's not the contrapositive. that's the converse, i think.

Gravity


  #357   Report Post  
Old June 28th 06, 06:58 PM posted to rec.radio.amateur.antenna
gravity
 
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contraposition in logic.

http://en.wikipedia.org/wiki/Contrapositive

affirmation of the consequent.

http://www.fallacyfiles.org/afthecon.html

Gravity


  #358   Report Post  
Old June 28th 06, 08:34 PM posted to rec.radio.amateur.antenna
chuck
 
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Cecil Moore wrote:
Gene Fuller wrote:
OK, energy exists, and it is even conserved.
Do you feel better now?


That's a good first step. Now where does the energy come
from that supports corona under fairweather conditions?


If the antenna is a vertical,
ungrounded, uncharged wire, it is a
conductor in an electric field (the
fairweather field).

The free charges in the antenna will
move so as to cancel the fairweather
field inside the antenna wire.

At the top of the antenna, there will be
a concentration of negative charge. If a
single strand of wire sticks out, that
concentration could be sufficient to
ionize the air and cause corona.

If the corona starting voltage is
typically 30 kV/cm radius, then a tiny
wire could ionize the air at only
300volts or so for a 0.01 cm radius.

http://home.earthlink.net/~jimlux/hv/corona.htm
Corona

Based on that, it would seem the
fairweather field can support corona
formation by itself.

If a charged particle now strikes the
uncharged antenna, free charges will
redistribute themselves to maintain no
net electric field inside the conductor.

The antenna's charge will increase until
it exceeds some breakdown threshold.
This process seems functionally similar
to that due to the existence of the
fairweather field, although either could
exist independently.

The question then seems to be whether
the redistribution of charges that
occurs when charged particles strike the
antenna causes a current in the antenna
which is detected by the receiver as
noise. I believe this is the question
Cecil has been posing.

It occurs to me that the current due to
charge redistribution could be rather
significant if numerous particles are
striking the antenna in a short time
interval. Even a corona discharge will
cause a redistribution of free charges
that may show up as a detectable current
at the receiver. This would be a
different effect from the noise
generating property of the corona itself.

Any thoughts?

Chuck

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Old June 28th 06, 10:02 PM posted to rec.radio.amateur.antenna
chuck
 
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chuck wrote:


If the corona starting voltage is typically 30 kV/cm radius, then a tiny
wire could ionize the air at only 300volts or so for a 0.01 cm radius.

http://home.earthlink.net/~jimlux/hv/corona.htm
Corona


As an update, I see that Llewellyn (not
W7EL) in 1975 established experimentally
that for a point radius of 0.01 cm, a
corona will be formed with fields of
only 100 V/m. These results differ a bit
from what would be predicted by
Paschen's curve.

73,
Chuck

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Old June 29th 06, 12:12 AM posted to rec.radio.amateur.antenna
Cecil Moore
 
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chuck wrote:
Based on that, it would seem the fairweather field can support corona
formation by itself.


Even though the fairweather current is 13 magnitudes below
the corona current?

It occurs to me that the current due to charge redistribution could be
rather significant if numerous particles are striking the antenna in a
short time interval.


Maybe aggravated by one element of the dipole being grounded
and the other floating?
--
73, Cecil http://www.qsl.net/w5dxp
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