[TowerTalk] Antenna

[K8RI]

On 5/20/2012 12:10 PM, Bill Ogden wrote:
> <snip>
>
> Half slopers are well known to be unpredictable. You may do better or
> worse. Even doing worse, I expect it would be better than the little mobile
> antenna you are thinking about.
>
> Except for a loading coil for 160, you can easily make your own. The
> antenna feed is simply a coax connector on a small metal plate. The plate
> is attached to the tower. The center conductor goes to the two sloper wires
> (one for 80m and one for 160/40).  The wires slope to somewhere near the
> ground, at something like a 45 degree angle with the tower. Part of the
> tuning is simply moving the wires around (to a greater or lesser angle) and
> playing with the lengths a bit.

This is what I made up. I would suggest mounting in with the coax coming 
in from the top so if the water seal gives out you won't get water in 
the coax.  It's a ready made drip loop.
http://www.rogerhalstead.com/ham_files/tower44.htm
http://www.rogerhalstead.com/ham_files/tower45.htm
http://www.rogerhalstead.com/ham_files/tower46.htm
http://www.rogerhalstead.com/ham_files/tower47.htm  Just a hose clamp or 
two to hold the bracket to the leg.  Even better would be a remote 
mounted tuner at this spot.

I mounted the feed point about 6 to 8 feet below the tribander.  There 
appeared to be no interaction, or I should say it didn't appear to 
bother the tribander. OTOH I'm assuming the tribander helped the half 
sloper.

As Bill says, they are unpredictable. Cut it to length, put it up and 
try it.  It may work great, and it may have been a waste of time.   I 
have the 160 half sloper to the S, a half wave, center fed,  75m sloping 
fan dipole to the WsW, and a half wave, center fed sloping dipole to the 
NE on 40.

Right now the coax isn't hooked up, but I hope to have it the coax back 
up before fall.

73

Roger (K8RI)