Cecil Moore wrote:
wrote:
If you don't want to modify the tuner, then
feed the 130' dipole with 11.3' of 450 ohm line and then go 50 ohm
coax
to the transmitter. Don't need a tuner. Or if you could lenghten
to
ladder line to 56' that would give a good 50 ohm match, no tuner
needed.

There's a DOS BASIC program on my web page that allows one
to enter frequency, dipole length, and type of ladder-line
to obtain the length of feedline that will resonate the
entire antenna system. Your 56' is pretty close to what my
BASIC program says (54' for 10.125 MHz, 130' dipole, 450 ohm
VF = 0.9). As you say, this length gives a virtually perfect
SWR of 1:1 on 30m - no matchbox required.

The DOS BASIC program can be downloaded from:

http://www.qsl.net/w5dxp/imax.exe
--
73, Cecil, W5DXP


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Hi Cecil, thanks for the info, I will take a look. BTW I used one of
Reg Edwards programs to get 56'. I'd say 2' is close enough for
engineering approximations. Have you bumped your program with his to
see how they compare?
Gary N4AST

wrote:
Hi Cecil, thanks for the info, I will take a look. BTW I used one of
Reg Edwards programs to get 56'. I'd say 2' is close enough for
engineering approximations. Have you bumped your program with his to
see how they compare?

Reg once compared them and they were close enough for
government work. I assume a VF of 0.9 for 450 ohm window-
line. Reg may assume something different or allow the user
to enter the VF. In any case, it won't be exactly 54' or
56'. Some adjustment will always be necessary.
--
73, Cecil http://www.qsl.net/w5dxp

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Cecil Moore wrote:
wrote:
Hi Cecil, thanks for the info, I will take a look. BTW I used
one of
Reg Edwards programs to get 56'. I'd say 2' is close enough for
engineering approximations. Have you bumped your program with his
to
see how they compare?

Reg once compared them and they were close enough for
government work. I assume a VF of 0.9 for 450 ohm window-
line. Reg may assume something different or allow the user
to enter the VF. In any case, it won't be exactly 54' or
56'. Some adjustment will always be necessary.
--
73, Cecil http://www.qsl.net/w5dxp

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Good enough!
Gary N4AST