On Tue, 7 Jun 2005 15:01:23 -0400, "Fred W4JLE"
wrote:

My 132 foot dipole is fed by lengths of 450 Ohm line of lengths depending on
frequency. The first part acts as a matching section to achieve 50 Ohms.
This feeds an electrical 1/2 wavelength 450 Ohm section the 50 ohm
impeadence is seen by the rig, while maintaning a 9:1 swr on the 1/2 wave
section. 450/50=9:1


Because you see 50 ohm (more or less) at the input of your "450 ohm"
(more like 400 ohm) line with an arbitrary impedance at the other end,
you incorrectly conclude the 450 ohm, variable length line is
operating at 9:1.

It appears that you've copied Cecil's design (ingenious BTW) but even
he admits to anywhere from 6:1 to 13:1 on his line.

For discussion purposes let's say that a 132 foot dipole, 50' above
average ground operated on 3.5 MHz has a feedpoint Z of about 61 -j63.
That's about SWR = 7.5 using 450 ohm as a normalizing factor.

Except for the effects of loss, the SWR *everywhere* on the line is
7.5:1. You don't get to say that 1/2 wavelength of it is operating at
9:1 and some other part is operating at something else.

Change the frequency to 7 MHz and the SWR is ~10:1 and so forth.