Hi Dick. Have had a fair degree of success feeding an older RBZ-66
EZ-Way crankup tower for both 160 and 80 meters. The towers lower
motorized limit is set at @40', which is where it stays most of the
time. Decided to load it at this position due to the potential of some
high winds here in the winter. BTW, it can be run up to 64' if desired.
Use 2 seperate, 3 wire, 18" cages, spaced 24" fron the tower to the 30'
level. At approx the 4' level, all 3 wires start to come together untill
they meet at @ 1' off the ground and then are routed to a matching
device. The cage is made from #10 stranded wire and an aluminum brace at
the top. Plastic 1/2" PVC pipe is the stand off at 4'. 80 meters is
gamma matched with a series capacitor, 160 uses an omega match, series
and a parrallel capacitors. The SWR and resonance point change
dramatically when the tower is raised, so the cable and upper sections
of the tower plus the antennas make it a tremendous effevtive height.
To what degree the stacked beams and cable play is strictly conjecture
on my part. All that I know, is that I can work most everything
on!...only a couple Dxpeditions have slippped through my fingers on
80...have not played with 160 too much because the matching caps are too
small and need replaced, can only take 100 watts! Let me know if you
want more details.
73,
Bob, K3GT
Dick Green wrote:
>
> > Don't forget that a crank-up has cables connecting all the sections.
> > It's one big lump of steel as far as being a conductor is concerned.
>
> Yes, but I'd be concerned that the sections are electrically bonded only via
> the contact area between the steel cables and pulleys. Wouldn't
> dirt/lubricant on the cable and in the pulley grooves tend to make that
> contact unreliable? I've seen recommendations on bonding crankup tower
> sections together for the purposes of improving lightning protection, but
> always felt that was not really feasible.
>
> Has anyone out there had success or problems shunt-feeding crankups on 160M?
>
> 73, Dick, WC1M
>
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