Jim Brown wrote:
> On Mon, 12 Apr 2010 21:07:25 -0400, Steve Bagley wrote:
>
>
>> I am putting up a tower and will need to run about 500 feet of coax.
>>
>
> http://audiosystemsgroup.com/Coax-Stubs.pdf
>
> 500 ft is a LONG run. You can easily burn half your TX power (3dB) in the
> coax. Many of us try to keep feedline loss under 1 dB. 500 ft of LMR400 is
> 3.3 dB on 10M, 2.3 dB on 20M. Half-inch heliax is 1.1 dB on 20M, 1.6 dB on
> 10M. To get under 1 dB on 10M you'll need 7/8-inch Heliax. :)
>
and with some hunting you should be able to find 7/8" removed from
commercial service at reasonable prices and quite possibly with 7-16
connectors. New connectors for 7/8" as well as LMR 1200 are expensive.
If I could find some locally I'd run 7/8" for the VHF/UHF runs on my
tower with LMR-600UF for the pigtails, or even Davis BuryFlex(TM) as
they are relatively short. OTOH the run for 160 should be larger as well
for ohmic losses.
I don't happen to like 1/2" heliax as I've found the LMR-600 to be more
rugged and easier to handle so I gave away most of the 1/2" I had along
with connectors. The half inch stuff is just too easy to kink.
When it comes to purchasing new, I'd go with LMR-1200 over 7/8" although
I've used a lot of 7/8" over the years and I can often find it at very
reasonable prices.
But as others have said, 500 feet is a longggg run.
73
Roger (K8RI)
> Another option to consider is CATV hardline. It's pretty low loss, it is 75
> ohm cable, so there will be a bit of mismatch, but that's why God made
> antenna tuners. It's often possible to get it free or cheap. You'll have to
> buy or scrounge connectors and a tool.
>
> Study the data on W3LPL's and K1TTT's website and save your pennies.
>
> 73,
>
> Jim K9YC
>
>
>
>
>
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