GAP Titan Help

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Jim Harris:
My new Gap Titan seems to have a problem.  The low point of all SWR curves on all bands is near the top of the band rather than near the middle of the band.  As a result the lower parts of some bands have an SWR of greater than 2:1.  Forty (40) meters is the worst with the center at about 7.5 Mhz.  The antenna is mounted seven (7) feet high on a steel mast.  There is no other major vertical metal for about 40 feet.  A different vertical was in the same location and was fine.

I've followed all the troubleshooting in the assembly booklet and have talked to GAP customer service.  The only help they gave was to do some simple continuity checks and assure the feedline is about 82 feet.

I've added 50 inches of wire to the counterpoise and that seems to have solved the problem except for 17 meters.  Now I have a long piece of wire hanging from my new antenna to get in the way or worse to shock someone when I'm transmitting.  This hanging piece of wire to me is not a good solution for several reasons.

BTW,  I've found the feedline must come straight down the mast and across the ground several feet.  Otherwise, all SWR's are above 2:1.  

I've tryed to join the Titan forum on Yahoo but it appears to be inactive.  I would really appreciate any constructive thoughts or help.

73,

Jim, AB0UK

Tom Rauch:
Everything you are observing clearly indicates the Titan has poor feedline decoupling and lacks a proper RF ground.

Whenever moving the feedline, changing feedline length, or adding a few feet to a "ground" or "counterpoise" wire changes the antenna behavior so much it means much of the current that could be radiating and making you stronger (or hearing better) is on the coax, mast below the antenna, and counterpoise or ground leads.

Sounds like an antenna design problem, rather than an installation problem.

73 Tom

Jim Walker:
One comment you made was "BTW, I've found the feedline must come straight down the mast and across the ground several feet. Otherwise, all SWR's are above 2:1."

If I recall, the yellow coax on the GAP Titan runs completely inside the antenna and should exit through an opening in the side of the aluminum about a foot from the bottom. In fact, I was advised at one time by GAP to do this instead of allowing the coax to exit at the bottom of the antenna.  This required me to cut off the SO-239, rerun the coax and re-solder the connector.

I had similar problems with my Titan but thought they were due to my particular location....being right up against the house for the full height of the vertical, custom counterpoise, etc.

I was only able to get my Titan tuned after many, many hours of adjustments including the addition of several feet of counterpoise wire.

I later sold it.

Good luck,
Jim

Ed Brooks:
Odd.  I've had a Titan for eight years, mounted three feet above ground on a steel pipe.  Outside of a serious problem on 75 meters, it has never had any of the problems noted here.  Resonance was achieved at 7.2 MHZ by adjusting the counterpoise as explained in the manual. There are no other adustements for any band unless the Titan has been revised.  There is a changeable capacitor in the top of the antenna which selects the resonance on 80 meters.  

The problem on 80 meters came with the application of 1 KW RF to it and the coax internal to the antenna apparently shorted, blowing, as GAP told me, a pinhole in the coax.  That shifted that resonant freq up to 4.4 MHZ.  GAP sent me a new center section, which is essentially a folded coaxial dipole for 80 meters, and that resolved that problem.

The yellow coax as supplied to me did not have the PL259 installed so I did not have to remove it and reinstall it.  The yellow coax does come out the small side hole in the base of the mast.  There was nothing in my manual about feedline length or angle.  Just connect RG8 and get on the air.  

The  highest SWR was about 2.1:1, at the low end of 40 meters, around 7.025, but that could be adjusted with the string and length of the counterpoise.  I could operate the entire band, though, with an Icom 706 without getting any SWR power foldback.  

It appears from what I'm reading here  GAP has seriously modified the antenna.  I'll have to download their newest manual.  The original version I have was almost Plug and Play.  

I'm in the desert with dry, sandy ground, yet my antenna has performed well.  I have now sold it, though it still has not been picked up by the new owner.  One problem with the Titan is mechanical connections between sections.  Waving in the wind it tends to loosen badly, and the screw holes expand so the screws cannot be tightened.  The solution is to take it down, and put stainless steel hose clamps at every junction and over every screw that holds sections together or wires to the mast.  And to guy the antenna tightly, to avoid shifting in the wind.

Good luck with yours.  I think you are getting bad information, but I have no idea why.

Ed

Jim Harris:
Thanks to everyone who replied.  The coax does come out thru the hole in side of the lower section and NOT thru the bottom of the tube section.  I've got into the Yahoo forum on GAP antennas and have found some ideas there but nothing conclusive.  One recommendation was not to use a lightning arrestor, but to wrap some braid around the feedline insulation and connect it to ground.  We've got 4 inches of snow on the ground right now so it will be a couple of days before I can get back out to the antenna.

Thanks again and 73.

Jim, AB0UK

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