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Old September 7th 06, 12:24 AM posted to rec.radio.amateur.antenna
Jim - NN7K Jim - NN7K is offline
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First recorded activity by RadioBanter: Aug 2006
Posts: 86
Default Are all RG8s created equal? appology

Thanks, Owen, and all and sorry to cause so much
grief. I fall on my sword! Have believed 99.44%
of what was in the old VHF'er Magazine, as was
started by a consortium of many engineers ,
originally by Doug Demaw, W8HHS, as editor, and
finally Loren Parks,K7AAD, an ex engineer from
Tektronix, and covered the Gamut of VHF, UHF, and
Microwave-- to early satelites and Moonbounce.
Was instrumental to me getting on air, many
moons ago. Tho much I've learned (and much I've
forgotten!) over the years. I have built tuned
coaxial finals, ect., and from former job,
haveing to use tuned lines (mainly,to couple
cavities together , and then tune them to
use on same antenna. IF those lines changed,
the things detunewhen you remove your test
equipment! Also, I get a little bull headded
after all theses years! Stuck on Stupid, if you
might! Owen- your charts are quite illuminating!
and, finely, The meter referred to , if memory
serves correct, was made by SWAN, just before
they went out of business (made for the "CB"
trade, more than amateur radio. and the lines
used in it were on a Printed Circuit board!
and this probably before they knew how to get
the correct impedence , on a p.c. board!
I shall return to my lair-- Jim NN7K


Owen Duffy wrote:
On Wed, 06 Sep 2006 04:45:57 GMT, Cecil Moore
wrote:

Jim - NN7K wrote:
... but it is
beyond the ability to have MORE power returned
to the source, than the source provided

Did you know a reflection coefficient can be greater
than 1.0?


It is true that reflection coefficient can be greater than 1.0.

The reflection coefficient *CANNOT* be greater than 1.0 where Zo is
purely resistive.

So, where a sampler is calibrated (nulled) on a purely resistive load
(eg 50+j0) as is most commonly done, it should never show a reflection
coefficient greater than 1. A reflectometer calibrated to a resistive
load and that shows a "reflected" reading greater than the "set"
reading is inaccurate / defective / a poor design.

Owen
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