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[TowerTalk] Vertical?

To: <>
Subject: [TowerTalk] Vertical?
From: Dick Green" < (Dick Green)
Date: Thu, 11 Jun 1998 14:23:35 -0400

Here's a copy of a message I sent to someone else on the GAP Titan. Hope
this helps.

73, Dick, WC1M

I've been using a GAP Titan for the past three years while planning my new
"hidden" antenna farm. It's an OK antenna, particularly for a temporary
solution or when you've got space restrictions or need a "view friendly"
multiband HF antenna (other multiband verticals are probably more
attractive, however.) On the other hand, the antenna has some definite

Advantages: 1) covers 8 bands pretty well, 40M-10M; 2) good SWR bandwidth
40M-10M (always under 2:1, typically about 1.5:1); 3) handles legal limit
power 40M-10M; 4) no radials; 5) fairly easy to assemble; 6) pretty rugged
when properly guyed.

I've worked 15 all-time new countries on this antenna. That may not sound
like a lot, but it was from #285 to #300, many of which were rare like Heard
Island (and the sunspots have been on vacation for the past two years.) I've
done OK in contests, but only when running 1500 watts. I chalked up 600 QSOs
in 10 hours on the GAP during CQ WPX and was able to hold a frequency for
some extended runs at 120+ per hour (it helps to have a semi-rare prefix.)

The GAP has lasted through three NH winters, which says a lot.

Disadvantages: 1) poor performance on 80M; 2) can't run more than 800 watts
on 80M or 75M (less if continuous carrier); 3) Counterpoise for 40M must be
free of snow and ice; 4) poor coax connection design; 5) poor standoff
insulator design; 6) self-tapping metal screws used to secure joints; 7)
difficult to install alone; 8) a  guy kit is not included.

1) As others have pointed out, it's basically a dummy load on 80M. It's just
a bunch of coax coiled up inside the upper tubing, connected to a
transmitting capacitor (factory selected to match your desired center
frequency.) Bandwidth on 80M is rather narrow and an antenna tuner is not

2) When I bought my GAP, the ads and manual did not say that you can't run
1500 watts on 80M. The manual does say you can't run legal limit in a
continuous carrier mode like RTTY, but it says nothing about intermittent
modes like CW or SSB. After I burned a hole in the internal coax, the
factory told me that you really shouldn't run over 1000 watts on 75/80.
However, they were very helpful in tracking down the cause of the problem
and replaced the entire center section and coax for free (it was a bear
to install.)

3) It's best to get the 40M counterpoise well off the ground. Mine was only
about two feet off the surface and used to get covered with snow or ice in
the winter, driving the SWR batty. In the summer, wet weeds touching the
counterpoise will cause SWR shifts and arcing.

4) The internal coax (thin stuff) is brought out the bottom of the tube and
just snakes across the ground to your main feed. Every year the critters
chewed through this tasty yellow coax just far enough so the antenna would
work on low power -- until I cranked up the amp and melted the last few
strands of shield braid. I finally got sick of repairing it on the fly
during contests (I used a crimp-on 'F' connector and F-to-UHF adapter in the
dark and snow once.) I fabricated a plastic box with a female UHF connector
at the bottom of the antenna which eliminated the dangling coax.

5) The tuning element standoff insulators could use some redesign. I had
problems the first year with SWR suddenly varying wildly. It turned out that
there had been some arcing between the antenna and one of the tuning
elements. It started via a stainless steel hose clamp that held the standoff
insulator. I had positioned the clamp's tightening screw inside the standoff
insulator (instructions were unclear on this), and that made it stick out
just enough to occasionally arc to the tuning element. Eventually, a
permanent carbon path was burned through the insulator, allowing the arc to
jump from the antenna to the tuning element. GAP tracked that one down very
quickly, too, and provided me with a free replacement insulator. All I had
to do was reposition all the hose clamps to get the screws out of the

6) As someone else mentioned, the cheap screws used to connect the elements
are for the birds. Once you use one, the hole is permanently reamed out. If
you have to unscrew the elements or the screw works loose, you have to put
in a bigger self-tapping screw.

7) The antenna is heavy and unwieldy enough that it takes two people to
mount it (it's dangerous otherwise.)

8) It's easy to guy, but no kit is provided -- even though it's an absolute

All in all, it's what it is -- a good temporary solution, backup, emergency
antenna, WARC band antenna, restricted space antenna, etc. If you don't
expect too much from it, it will please you.


Here's an update as of 12/97:

I recently augmented my antenna farm with a TH7 tribander on a 70 foot
crankup tower, a full-size 40M vertical with 60 radials (to be one element
of a 40M 4-square when the snow melts), and an 80 meter vee at 60 feet. As
you might expect, comparisons with the GAP are ludicrous. The beam is
anywhere from 10db to 40db louder on receive (and presumably on transmit.) I
get lots of reports now that I'm "LOUD!". Sometimes, the GAP barely keeps up
with the rear of the beam, which is about 22 dB down from the front. What's
more surprising is that the 40M vertical exhibits an improvement of 10dB to
20dB over the GAP. I would have thought it would be closer. Of course, the
80M vee kills the GAP, with 20dB or more being typical.

I've discovered another construction problem with the GAP. After I relocated
it to a new position in the woods, insects moved into the counterpoise
standoff insulators. The first time we had a good rain, the insect bedding
got soaked and when I then transmitted at high power, there was an arc
between the counterpoise wire and its metal supports. The arc made a
permanent carbon track in one of the standoff insulators. I was totally
unable to remove the track, even with sandpaper and a file. I ended up
ordering a complete set of replacement insulators and new counterpoise wire
(the old wire barely lasted two years -- it's ready to disintegrate.) It all
came to less than $20. Still, it's a poor design. Next time, I'll plug the
holes in the insulators with coax seal.

Hope this helps.

>Greetings, TowerTalkians --
>     I've got a local ham who can only install an HF vertical in a kind of
>restricted spot. He can only put a couple of radials out but they'll have
>be bent, shortened, etc. in order to get them in so he's looking at the 'no
>radials required' vertical antennas. He's looking at the Gap Titan, Hy-Gain
>DX-77 and Cushcraft R-7000. If you had to make this decision, which one
>you buy and install? All comments welcomed. Tnx.
>Cheers,  Steve  K7LXC

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