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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