[AMRadio] Antenna question... simple but I've never used a very long wire...

[W7QHO at aol.com]

In a message dated 7/9/02 6:01:37 PM, ka1iic at prexar.com writes:

>I want to set up a long wire antenna for standby purposes...
>
>I am considering a 500 foot end fed type...
>
>What I need to know (I've read the handbook but...) is 'real' information
>that deals with the loading of one of these on 75m and the practical tuner
>that could be used...
>
>'practical' information welcome hi hi...

Vince,

Well, 500 ft. would be close to two wavelengths long.   Would be voltage fed 
so a simple "L" network should do the trick.  You can find a description of 
one of these in just about any ARRL Handbook and/or Antenna Handbook.  You 
will need a modest ground system at the feed end (couple of ground stakes, 
half a dozen short radials, etc.).  Keep the ground lead to the tuner as 
short and direct as possible.  I currently use a remotely controlled tuner 
out in the yard setting right on top of the ground point.  If you're trying 
to operate with the tuner in a second story shack or otherwise far removed 
from mother earth you may have to use a quarter-wave counterpoise to keep 
from getting "bit."  Once, though, I operated from the top of a four story 
building successfully with a similar antenna by using the heating system as a 
ground.  As to component values, I usually use a 30 - 40 turn roller inductor 
and a 150 - 200 pf variable to match to a 50 ohm line on 75M.

A 500 ft wire on 75 M will start to get directional off the ends.

Good luck.

Dennis D.  W7QHO
Glendale, CA