Will,
The key to building an efficient and reliable repeater is to put the
majority of the money and effort into the components that are the most
difficult to install and the most costly to repair or replace. That
means that your antenna and feedline should be the best that you can
buy, and should be installed expertly with the appropriate hardware.
You can always replace or upgrade the equipment down in the radio room,
but safe access to the antenna and feedline may require shutting down
other transmitters or may (and probably will) be on the coldest or
windiest day of the year. So, don't scrimp on the tower stuff!
Belden 9913 is a good low-loss cable, but it is inappropriate for
antenna feedline. One "rule of thumb" is to select a feedline that has
no more than 1.0 dB of loss at the higher of the two frequencies in the
repeater pair. Based upon that rule, you should use at least 1/2" foam
(such as Andrew Heliax LDF4-50) for a 2m repeater and at least 7/8" foam
(such as Andrew Heliax LDF5-50) for a 70cm repeater. This is based upon
your statement that your feedline will be 100' long.
73, Eric Lemmon WB6FLY
n2odw wrote:
>
> Hello to the group,
>
> I'm new to this group and also new at trying to build a repeater
> system. My main question is about line lost. Could anybody tell me how
> to figue out line loss out for the purpose my repeater application and
> for the use of the antenna cable I have? The cable is Bendel 9913 @
> 50ohm, planning to use 100ft. Thanks
>
> W4WWM / Will
>
>
> Yahoo! Groups Links
>
>
>
>
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