John Doe wrote:
2 items
1] I have since found that Hustler did not make a 160m coil, but
Pro-Am/Valor makes this item (VAL PHF160 = VALOR 160M 8' 3/8-24 WHP/PHF
160B) that I might be able to substitute in its stead.
2] I live in a Antenna Restricted Retirement Community (NO I CAN'T MOVE),
and I have a 40ft pine tree in my back yard. I thought that I might try the
above mentioned item in conjunction with lets say a "LDG AT-200 Pro"
auto-tuner or equivalent. (Note - I cannot run any wires from the house to
the tree in the air - they have to be buried. Also I do not have any
fencing and my rain gutters are grounded.)
My idea is to strap either a metal or pvc painted pole near the top of the
tree, with a mount bracket for the whip (of course all painted to look like
the tree). I will have to feed it with RG-8x (painted) run down the tree and
buried in a trench to the house.
As far as radials go - They are out of the question. Instead - what do you
think if I should just roll up say 250ft of 13ga or so of single conductor
wire about a foot in diameter, attached at the base of the mounting bracket
(hung in the tree) and use it as a counterpoise? I might be able to hang in
the lower branches of the tree - a waterproof box with a loading coil and
attach the counterpoise there instead?
Whoa, quite a conundrum there, John. It seems to me that you're best
bet would be to put up as much vertical wire as possible, (probably some
30 feet, and have a loading coil in the circuit, then have a tank
circuit at the bottom to tune the wicked impedances you'll be looking
at. You'd want at least the equivalent of 1/3 wave. On 80 meters, you'd
be looking at around 70 feet or so. 160 meters is looking for more
inductance yet. If you don't have a real pressing need for 160, it would
be a good one to forgo.
The tank circuit will probably be needed even if you use an autotuner.
It is a simple LC with variable cap and coupling transformer. Attach the
lower part of tank to a ground rod, and give it a shot.
Here is a link from Cebik:
http://www.cebik.com/fdim/fdim4.html
You should be able to get fair performance out of this one - nothing
great mind you, but it is after all a compromise antenna.
- 73 de Mike KB3EIA -