In article , highlandham
wrote:

On 28/06/10 13:23, •R. Measures. AG6K wrote:
In , "
wrote:

Hi

I have a 50 ft tower just ready to throw up something to operate.

Cost is the problem but I have a lot of parts to build. I want to put up a
dipole (I have a manual all band tuner) and my question is should feed it
with ladder line or feed it with coax and then run each leg about 68 ft .

Second idea is I have an old aluminum omni antenna that used to have 3 traps
within it, however at that height it will come down quickly as this antenna
is meant to be on the ground (no ground planes) so I want to make this omni
as long as practically possible and tune it to utilize it as best possible.

Any suggestions? This is really all I have to work with. Only want to climb
this thing a couple times and hope its good for the winter.

• RON -- I would install a pulley on a short arm at the top of the tower
so that I could rig a halyard to raise and lower the middle of an
inverted-V antenna wire. One end of the wire is the feed point (fed
against gnd) and the unfed end has an insulator and a tie off to a point
at least 7' above ground. The feed point Z can be up to several
kilo-ohms, so an L-network is used to match the feed Z to 50-ohms. A
remote controlled L-network is a good way to go. When this antenna is a
half-wave, it's called a Hertz antenna and it acts like a plain-vanilla
halfwave inverted V dipole -- but with the advantage that it can be tuned
to work on any frequency for which the wire length is at least 0.2
wavelengths.
- notes - Hertz antennas have an advantage in the Winter since the
feedline is not up in the air. /// The most durable antenna wire is
braided phosphor bronze, #22 will easily carry 1500W. /// when viewed
from above the wire must be pretty much is a straight line and not fold
back on itself.
------Rich, AG6K
===================
Tnx Rich for the above useful advice, which I have filed.

• ur welcome Ron

Frank GM0CSZ / KN6WH

--
Richard L. Measures. 805-386-3734,AG6K, www.somis.org