since your antenna will be close to ground, there may be interesting swr
issues.  Using 75 ohm coax will probably make them worse, not better.  You
would only use 75 ohm coax if your feed point impedance was less then 50
ohms.  This is most common with a vertical or directional type antenna.
Dipoles, or random wires, or long wires usually exhibit much higher feed
point impedance.  I suppose if you have a tuner you could use 75 ohm coax if
that is all you have for the time being, but try to use 50ohm if you can.
for random wire, or end fed resonant wires, or long wires, 300 ohm, or 450
ohm latter line works better because it is actually closer to the feedpoint
impedance of the antenna.
73
\Colin, V A6BKX
----- Original Message ----- 
From: "Shaun Oliver" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, July 12, 2008 10:38 PM
Subject: antennas


> HI all, considering I'm going to mount my antenna aprox 15 foot off the
> ground, is there any difference as to whether or not I choose to use 50
> ohm coax or 75 ohm coax? if so, how big a difference is there?
>
> -- 
> Shaun,
> vk2fese,
> web sites:
> http://www.myspace.com/blindmanshaunoliver
> http://blindman.homelinux.org/~blindman/
> skype: brailledude
>
>
> -- 
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