Re: Topband: GAP Vertical Question

[DAVID CUTHBERT <telegrapher9@gmail.com>]

Don,

a 36" helium balloon filled to 32" is enough to lift 130' of #26 wire in no
wind. It doesn't take much wind to blow it horizontal. A half wave vertical
suffers more as it is blown down so I think it's best to fly 130' at the
most. Flying the balloon from a 40' or taller mast would allow the 130'
vertical to become an inverted-L as the wind picks up. Mounted 100' out
from  the shore at the Salt Lake the ground loss is virtually zero. The
water depth is 6" at that point.

In the ARRL 160 meter 'test this year the balloon blew into a sharp bush
and perished. That may be the last balloon I fly at the lake and a 50' base
loaded vertical will take its place.

Given that a half wave vertical has a base impedance of over 1000 ohms and
a single ground rod in dirt is 100 ohms at most not a single radial is
needed to obtain close to 100% radiation efficiency.

     Dave WX7G
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