[TowerTalk] Feeding wire yagis (Slagis?)

[Ron DeBry]

Having gotten a rope up near the top of my ~110' pin oak tree, I want
to hang a 3-el inverted vee yagi for 40 meters. The catenary will run
to the top of a 60' tree about 80-90' away (will this be a "Slagi" for
"sloped yagi" ? - sorry, Tom).

I'll be lucky to get the V angle any above 90 degrees, so I'll be
looking at a feedpont impedance down around 20 ohms. Any suggestions on
how best to feed it? My ideas include a beta match (but how would I
physically construct it?). This would also mean a balun and coax,
adding weight and sag. Alternatively, I could run ladder line. I've
used my Johnson Matchbox on lots of high-impedance antennas - anyone
have experience matching 450 ohm line connected to a very low
impedance?

Thanks for any ideas.

BTW - I got the rope up in the tree using a method I've not seen
before. Up to ~70 feet I'm pretty accurate with a slingshot, but I need
either a stronger slingshot (maybe - I only have the 1) or longer arms
(not quite so likely) to get higher. Also, lots of my tree fishing is
too near the house, the neighbor's house, or cars, to risk flinging
lead weights around. Throwing a hard rubber ball works OK, but my arm
tops out around 60 feet. I've never shot a bow and arrow (sounds like
highly increased risks, compared to the lead weights, as well).

But, over there in the corner is my tennis racket. Hmmm... Memories of
whacking a ball straight into the air after netting yet another easy
volley.....  A couple of practice whacks without fishing line convince
me that it should work. My first real shot  (at a different, 70' tree)
was low, but long (cleared the next yard cleanly, and about halfway
into the yard beyond that). A quick attitude readjustment about
elevation adjustments, turn to the pin oak, and bam - there I am about
100' up. Next warm spell I'll try again to see if I can catch the very
top of the big oak.

73, Ron


Ron DeBry   K8KM       (ex WA6DGX)

Department of Biological Sciences
Box 210006
University of Cincinnati
Cincinnati, OH 45221-0006

(513) 556-9743                       ron.debry@uc.edu


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