Any coincidence between 1/4 wave in free space and the actual length of
the 1/2 wave line is purely an accident of the numbers. The line is best
modeled as an inductor to with caps at each end that resonants at 144
MHz. A line less than 1/4 wave long appears as an inductance that
depends on its length and impedance.
jeff, wa1hco
craxd wrote:
John,
I read that and your correct, 53 cm is 20.86614173". I'm thinking they
may have just rounded off the number to that, I'm not sure. It's very
likely that's what they done as it happens a lot when folks are to
lazy to type the whole number length.
From the website, the dimensions was, quote;
"The plate line is a 55mm dia. copper tube 53cm long, from bottom of
cooler to top of line."
Best & 73's
Will Matney
JMLTINC@aol.com wrote:
Hi Will-
Yep, just checked it, PA3CSG's site is down.
There is another pix at http://www.nd2x.net/PA3CSG-2.html
Sorry for the confusion, the 3/10" is the difference between the
actual length of the line (20.8") and 1/4wl (20.5" at 144MHz). That
is to say the line is 3/10" longer than a true 1/4wl line. How does a
line that is 3/10" longer than 1/4wl line become a 1/2wl line?
Thanks-
John, N9RF
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