[TowerTalk] Coax Type

[Pete Soper]

Hi Roger,

You wrote:
> I am installing two antennnas (402CD and an A4)  in two different trees
> that are about 50 feet apart and 250 feet from the shack.  Total length to
> each of the antennas will be 300 and 350 feet.  My questions are 
> 
> 1.  What type of coax should I use?  Is 350 feet to far for RG213 or RG8?
> 
> 2.  If I use a switch box any suggestions on a manufacturer?

I recommend you get Dean Straw's transmission line modeler program "TL"
from the ARRL download site. It's called "tl.zip" and can be gotten from here:
      http://oak.oakland.edu:8080/pub/hamradio/arrl/bbs/programs/

It will let you do "what if" type things and see just how many watts will
get into your antenna with different types of line. There is a really nice
follow-on version of this program called "TLA" that Dean includes with the
current ARRL Antenna book. Once you've gotten a feel for how the program works
you can put the data in for various commercial lines that the program doesn't
have in its menu and zero in on the price/performance point that is right.

Both programs do more than just calculate loss too. You can get quite an 
education about L and T networks and develop a feel for what kinds of mismatch 
scenarios are OK and what types present serious challenges. 

Anyway, the quick answer is that in my opinion using RG213/RG8 with a 350 foot
run would be like dropping the antennas several feet in height or knocking 
off an element or two.

Regards,
Pete
KS4XG

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