Feed Line advice to KAT100

[Nigel-14]

Would welcome advice from the more experienced on a suggested feed line
arrangement.

I am erecting a horizontal loop (more rectangular than square) which will be
95 to 105 metres in circumference, up about 8 to 10 metres.    This is to be
connected to a KAT100 tuner.   The loop configuration has been chosen as the
K2 is on second floor and this enables the feed line length to be only 5
metres in anticipation of high swrs and potentially high feed line losses.
Also for low neighbour visibility.     The loop passes through trees to be
in the clear but it is not possible to reduce the length to 80m, and tune it
to the CW parts of the bands, without hitting tree branches.    I will be
operating 80 through 20m
Thoughts for the feed line are:-

1) Use 5M of RG213 from Ant to tuner

2) Use 3M 450 ohm ladder line to Balun (BL1 4:1) and then 2m coax. (this
gets the balun out of the weather.

3) Balun at the ant (?:1) plus RG213 to tuner

Which of the above is considered preferable and why?   Other suggestions?
Thanks
--
73,  Nigel, ZL2DF

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[Jim Brown-10]

On Mon, 5 Sep 2005 20:23:28 +1200, Nigel wrote:

>3) Balun at the ant (?:1) plus RG213 to tuner

This is a good configuration if the antenna is long enough
to load on all the bands on which you want to use it. BUT,
with a feedline only 5m long, and a transmitter power of
only 100 watts, RG-213 is larger than you need. RG-59 or
RG-8X would work just fine unless you want to run much
more power. Feedlines must be far longer than 5m before
losses or standing waves become a problem, and the smaller
cable will be both more manageable and less visible.

One other consideration though. If you want to load the
antenna as a long wire against "ground" or a counterpoise,
you would not want a balun at the antenna, and would need
balanced line with a balun at the antenna tuner. I use
this configuration for a limited space antenna here in a
Chicago residential neighborhood as my only antenna for
160 and an alternative antenna for 80 (that works better
in some directions than the same wire loaded as a dipole).
See

http://audiosystemsgroup.com/K9YC/k9yc160TopLoad.htm

and

http://audiosystemsgroup.com/K9YC/k9ycant.htm

73,

Jim K9YC


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