[TowerTalk] Gap Voyager gotchas

[Rob Atkinson, K5UJ]

I bought a Voyager for 160 m.   Before I put it up, some people I trusted 
advised me to put up an inverted L instead.  That I did, and sold the 
Voyager to a friend, new in box for about 1/2 what I paid so I think he got 
a pretty good deal.   I've heard one Voyager on 160 and the signal was 
lousy.  OTOH the inverted L with 101 radials (so far) is working quite well 
considering its height and location (only 25' up 180 deg., then another 25' 
at 135 deg. and the rest horiz 90 deg.).

The Gap "radials" are extensions of the bottom half of a vert. off center 
fed (i.e. asymetric) dipole that has a feedpoint matched to ~50 ohms with 
coax stubs, caps, and linear loading.  Since the extensions are very close 
to the earth's surface in terms of wavelength on 160 m. I think there is a 
lot of rf lost in coupling from them to earth.   If you were able to elevate 
the whole thing quite a bit so the 3 extenstions were around 30 feet away 
from ground surface that loss might be lowered.    The top part above the 
insulator is significantly small at 1.9 mhz and therefore not very efficient 
on 160 even with the top loading.  You have to ask yourself--if this were a 
wonderful medium wave design, broadcasters would be using something similar 
and saving $$$ on paint and aircraft obstruction lamps.

If you want to just have a taste of 160 it may be okay as it seems to work 
pretty well on 80 and 40.  If you want a good antenna on 160 I'd advise you 
to go with something at least 60 feet (~45 degrees) tall, base fed on an 
insulator over a lot of radials.  You can run a wire off the top (inv. L),   
   or ground the vertical with a metal arm at the top sticking out to hold a 
wire hanging down to your feedpoint to make a folded 1/4 w. monopole (what 
hams call shunt feeding which I think is a confusing and nondescriptive 
term).    If you don't care about the swr, and want to run qro, use robust 
feed such as 213 or 1/2 inch heliax and tune in the shack.  If you want to 
be picky, put a matching network at the feedpoint.  hope this helps you or 
others in ur position decide what to do.

73,
rob / k5uj

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