In a message dated 11/12/01 6:31:07 PM Pacific Standard Time,
RCARIELLO@si.rr.com writes:
<<
Legion or fact?
When feeding a tri-band beam I have been told that a length of 125 feet or
multiples of is the best length for your coax to be. This is based on RG213
with a velocity factor of 66.
Another person said there was a chart once published showing what lengths of
coax to stay away from with all the ham band listed. I have not been able to
find this chart. Would anyone happen to have one?
Are there lengths that work better then others?
Rich AA2MF
>>
Rich Try multiples of 45' 7" for 1/2 multiples for .66 VF based on a base
frequency of 7.125 MHz or 91' 2" for 3.562 MHz. It seems to give "clearner
SWR measurements" with all bridges, (some bridges give different values with
different legnths not related to the coax loss) the antenna Z can be measured
at the end of the feedline fairly accurately and it seems easier to match the
loads at its end. Other problems seem to just go away. If you cut all your
coaxes this way as I do it simplifies it when you use your coaxes for phasing
2 antennas.
It works with open wire line also for many more reasons. For .98 VF (spacer
every 3') open wire line use 135'. Use 123' for 450 ohm ladder line of .89
VF. K7GCO
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