There are certain antennas that I have seen where the coax length is
critical - these are either special antenna configurations. One such
configuration is twin or multiple element antennas where the length of the
coax is used for optimal phasing. The other I have seen is for antennas
that are non-resonant and the coax is used as part of the matching network,
making it part of the antenna. I am not even sure why some antenna
manufacturers choose such designs, but I have seen them. This is less than
optimal for many reasons. One reason being, your coax becomes part of the
radiating element. This takes RF power away from the antenna - and puts it
on the coax, inside the vehicle or in the shack with you, where it can only
cause problems you dont need. I have seen a shorted coax (absolutely NO
power at the antenna) match up great to the radio because it happened to be
exactly the right length to the short.

Take a tip from me, if the antenna installation instructions say to cut
the coax to a specific length and it is not a phased, multi-element antenna
then stay away from it.

Hope that helps.

Wade

"Noon-Air" wrote in message
...
Instead of wasting bandwidth on stuff that cannot be changed by the general
populace (CW requirements) or stuff that is just to jerk peoples collective
chains (E-Bay posting in this NG), how about something that might even be
technical in nature??? How about the answer to this question??.....When
cutting the feedline for a dual band (2m/70cm), for maximum performance, it
needs to be cut to multiples of electrical half wave length. Does it need to
be cut for 2m? or 70cm? a combination of both? or split the difference?


--
Steve @ Noon-Air Heating and A/C


When a work lifts your spirits and inspires bold and noble thoughts in you,
do not look for any other standard to judge by:
the work is good, the product of a master craftsman.
- -- La Bruyere