[TowerTalk] Gap Vertical

[Bill Frede]

I have owned a GAP Challenger (80m-10m) for 3 years now.  For a vertical it's a pretty good performer and on 40m it is an excellent antenna for DX.  On 80m it is worthless.  On all bands except 20m the antenna exhibits good SWR curves for the full band.  On 20m it runs around 2:1 and I just can't seem to change it.  But it does perform well on 20m and I have received great reports from Europe and Russia on SSB.  On 15m and 10m I haven't had too much success with it.  I mainly use the GAP for (S&P)contesting and go over to someone else's station if I want to be competitive.
Some things to remember about the GAP.  It is fragile antenna that is very top heavy.  They pack a bunch of folded up coax in the top section to make it almost work on 80m.  What a waste of coax.  It is all held together by sheet metal screws that will work loose over time.  I replaced all the screws that are used for mechanical support with SS bolts that go through the antenna.  The screws that are used to make the electrical connections were replaced with the next larger sheet metal screw.  No problems now.  
The antenna must be guyed.  I use Kevlar cord to tie it down.  A 4 guy system works much better than 3 guys.  I made a plexigless collar to fit around the antenna to tie the guys to.  Place the collar about 2/3s the way up the antenna.  Any lower and it will shake itself to death in a windstorm.
You need 3 counterpoise wires to make it work properly.  The SWR curves can be changed by adjusting the wire lengths.  I have had this antenna up at 5 locations with similar performance at each spot.  I see no difference in performance in ground versus roof mounting.  On the roof, the counterpoise wires need to be lengthened about 5 feet. 
I have no experience with the other GAP antennas but I have read comments that make me believe they are similar.
My advice, try to find a used GAP.  There are a lot of people that hate them so you could probably find one at a good price.
73 es GL,
Bill Frede  W7II
Pocatello, ID

----------
From:  Martin Gary[SMTP:n3hrt@eagle1.eaglenet.com]
Sent:  Friday, August 01, 1997 8:11 PM
To:  towertalk@contesting.com
Subject:  [TowerTalk] Gap Vertical

Hi all,

I'm afraid that I'm going to start a big thread with this one... I'm
sure this has been talked to death, and in my defense I DID look in the
archives before posting this. 

Here's the deal. I have about $300.00 to spend and I want to buy an
antenna that will cover 40-10 meters. I considered a tri-band beam, but
then I would still be looking for something for the WARC bands. Besides,
getting a beam is just the tip of the iceberg. You still have to buy a
rotor, and everyone knows how expensive they are. So, after looking thru
all of my catalogs, I decided that one of the Gap verticals might be a
good choice. I think the Titan DX is the one that  would work best for
my needs. I have a 40ft. telephone pole that I could mount it on. 
snip

Martin, N3HRT.



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