Gary, N4AST wrote:
"Do you know of anyone that has an infinite length of transmission
line?"

I may as soon as the line constructor is finished. Now, I can`t say that
I do, but for some purposes a line of random length which is terminated
in Zo serves as well as an infinite line of the same Zo.

A dissipation line, of course, must have enough length not to overload
the termination resistor at the end of the real line which does have an
end.

Best regards, Richard Harrison, KB5WZI

Someone sed:

" Do you know of anyone that has an infinite length of transmission line? Or
an infinite anything? :-)."

===============

Some of these threads are PRETTY LONG, approaching infinity???

73 de Jack, K9CUN

I've always taken it for grunted

I have often grunted when taking transmission line measurments, but I try to
keep it to a low volume.
Your ohmmeter will budge if you terminate the line with a short, or some
resistance. The Characteristic Impedance (300/75/50 ohms) is an AC or RF
measurement, and can not be done with a DC VOM. The devices that the average
Ham has on hand include, antenna analyzer, grid dip meter, and rf signal
generator. Transmission line measurements with these devices can been found in
the ARRL books or with the instruction books with the instruments.
73 Gary N4AST

As stated in other responses, it is not measured with simple instruments.

Every wire has self inductance. It can be calculated using commonly
available equations.

Every pair of wires has self capacitance. It can be calculated using
commonly available equations.

So, the 300/75/50 ohm term, characteristic impedance, is the square root
of L/C

W1MCE

Dan Jacobson wrote:

Dear antenna pros, I've always taken it for grunted about the
300/75/50 ohms of TV ribbon, coax, etc. But how does one measure it?
My ohmsmeter doesn't budge. Is there some standard formula, like wrap
grandma 100 times, with the far end connected to a cheeseburger in her
mouth, the near end finally displaying the characteristic 300/75/50
whatever ohmses?

Someone sed:

"So, the 300/75/50 ohm term, characteristic impedance, is the square root of
L/C"

This is an *approximation* that is useful when complex arithmetic is over the
capability of your calculator or if the imaginary components of the formula for
Zo are negligible.

At the usual HF through UHF ham frequencies the imaginary components are
negligible so the approximation suffices.

UNITS: 10-pF capacitor. 10-pF is hypenated when used as a modifier, i. e.,
adjective.

Others: 10-ft pole, 5-cent cigar, 2-dollar pistol, 12-V battery, 500-mile
track.

73 de Jack, K9CUN

JDer8745 wrote:

snip


UNITS: 10-pF capacitor. 10-pF is hypenated when used as a modifier, i. e.,
adjective.

Others: 10-ft pole, 5-cent cigar, 2-dollar pistol, 12-V battery, 500-mile
track.

73 de Jack, K9CUN


Partly correct.

The use of "10-picofarad capacitor" is preferred under the standard rules of
English and the NIST style guide. The use of "10-pF capacitor" should be
replaced by "10 pF capacitor" according to NIST.

See section 7.2 in http://www.physics.nist.gov/Pubs/SP811/contents.html

"Even when the value of a quantity is used in an adjectival sense, a space is
left between the numerical value and the unit symbol. (This rule recognizes that
unit symbols are not like ordinary words or abbreviations but are mathematical
entities, and that the value of a quantity should be expressed in a way that is
as independent of language as possible.)"

"When unit names are spelled out, the normal rules of English apply. Thus, for
example, ‘a roll of 35-millimeter film’ is acceptable."

73,
Gene
W4SZ

Jack, with all due respect, you need a hobby...


"JDer8745" wrote in message
...
Someone sed:

"So, the 300/75/50 ohm term, characteristic impedance, is the square root
of
L/C"

This is an *approximation* that is useful when complex arithmetic is over
the
capability of your calculator or if the imaginary components of the
formula for
Zo are negligible.

At the usual HF through UHF ham frequencies the imaginary components are
negligible so the approximation suffices.

UNITS: 10-pF capacitor. 10-pF is hypenated when used as a modifier, i.
e.,
adjective.

Others: 10-ft pole, 5-cent cigar, 2-dollar pistol, 12-V battery, 500-mile
track.

73 de Jack, K9CUN

w4jle wrote:

Jack, with all due respect, you need a hobby...



He was just getting his 2-cents worth in! :-)
--
--------------------------------------
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Beating it with diet and exercise!
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--------------------------------------
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--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

Someone sed:

"So, the 300/75/50 ohm term, characteristic impedance, is the square root of
L/C"
==================

Not always!

73 de Jack, K9CUN

To a first approximation ... YES. In the context of providing a simple
explanation, an introductory level explanation, as in the context of the
original question ... YES.

In the interest of more advanced analysis:

Zo = SQRT[[R + jwL]/[G + jwC]]

In a lossless line that converges to SQRT [L/C].

DD

JDer8745 wrote:

Someone sed:

"So, the 300/75/50 ohm term, characteristic impedance, is the square root of
L/C"
==================

Not always!

73 de Jack, K9CUN