Reg Edwards wrote:
R.L.Varney himself never gave a value to Zo. He didn't need to. He
was
concerned mainly with 14.15 MHz. It would be unfair to accuse him
of
not understanding the serious effects of Zo on other bands.

However, in The ARRL Antenna Compendium #1, he did describe the
matching section well enough to calculate his Z0. It is #14
copper open-wire separated by 1.75 inches. I'll bet that's
an improvement over 300 ohm twinlead.
--
73, Cecil
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Cec, the facts are, G5RV never mentioned Zo, either because he never
attached any importance to it, or he didn't understand its relevance
to other bands.

When considering other than 14.15 MHz perhaps he should have done. In
any event, everybody else has followed suit.

Now we have the situation where dozens of people are busily seriously
comparing all-band versions, one with another, and unknown to each
other they are all using different value Zo transmission lines.

Many of those who purchased the antennas, or just copied G5RV's
construction, havn't the foggiest idea what their particular Zo is.
Yet, from an analysis point of view, which you are involved with, it
is a crucial matter.

Your own Zo is a non-standard 375 ohms because you measured it. Yet
you describe its performance to others as if everybody else's Zo is
the same, whereas there is no hope of anybody else reproducing your
particular results.

Its all a load of nonsense!

If anybody, at this very late stage in the art, should still wish to
acquaint themselves with the less than mediocre performance of a G5RV,
then download program DIPOLE3 from website below.

DIPOLE3 is a general purpose program which deals with a dipole of any
length, at any frequency, plus balanced-twin feedline of any length
and any Zo, plus balun, plus coax line of any length and Zo, plus
L-tuner. So it happens to include a G5RV.

All the data for the original G5RV can be inserted in the program by
depressing one key. Modifications to the system, such as changes in
Zo, can easily be done and changes in performance immediately seen.

The final important output figure is overall loss between transmitter
and radiated power. Individual losses in the antenna, in the two
transmission lines, and in the tuner, are reported seperately. Even
the tuner L and C settings and their circuit locations are predicted.

It is very easy to sweep over the HF frequency range to check when low
swr happens to fall into amateur bands. (Unfortunately it doesn't do
this very often.)

It is also easy to change the length of transmission line (as Cecil
recommends and advertises) to try to obtain an swr of less than 2:1.
But you can use any dipole length other than 102-feet to play with
this useful aspect.

Accuracy is better than needed for the intended purposes and is
generally as good as the accuracy of program input data. There is only
one known trivial bug which occurs when dipole length is extremely
short compared with wavelength. But clearly this is not of
consequence.

What more could you want from a G5RV? There's nothing to do but erect
it and then compare it with a dipole of any other length with an open
wire feedline of thick wire, of no particular length, all the way to
the shack. Plus a choke balun.

I'm still on Red, South African, Western Cape.

Download DIPOLE3. Its free to USA citizens.
----
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Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
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