On Tue, 10 Jan 2006 21:14:40 GMT, Owen Duffy wrote:

On Mon, 09 Jan 2006 15:50:20 GMT, Cecil Moore wrote:

Ricke wrote:
If SETUP right , There the best HF I've ever used.

Maybe the only one? :-) The G5RV, with tuner, is a pretty
good 80m, 40m, 20m, and 12m antenna. If the series section
is varied from 20 feet to 36 feet, it becomes a very good
all-HF-band antenna. With the addition of a parallel 1000pf
capacitor with the series section at 22 feet, on 75m my "G5RV"
has SWR of 1.3:1 and works as well as a 75m 1/2WL dipole.

Is this the antenna described at http://www.qsl.net/w5dxp/G5RV.HTM ?

I have made a mistake during my analysis, let me try again:

In that article, on 75m you model a feedpoint impedance of 36-j324,
28' of 300 ohm ladder line, for a Z of 15+j4 (seems to indicate 48.2
deg length of 300 ohm line with 0.007dB loss (optimistic)).

At that point, were 50 ohm coax connected directly, the VSWR at the
load end of the 50 ohm coax would be 3, however you shunt the 17+j4
with 1000pF to give a new Z of 17.3-j3.0 that results in a VSWR at the
load end of the 50 ohm coax of around 2.9, almost identical to the
case without the capacitor.

Presumably when you say that the capacitor improves the VSWR on 75m,
you mean the VSWR on the coax. Did I miss something, how does the
capacitor improve the VSWR on 75m?

Owen

PS I couldn't make the numbers work for 22' as in your quote, where I
got a VSWR at the load end of the coax of 27. I couldn't see where the
VSWR of 1.3 comes from?
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