[TowerTalk] Problems with the KT36XA

[Larry Schimelpfenig]

I certainly agree with what Tony has said. Seeing the severity of the 
situation, my first inkling is to think it's probably a problem with one of 
the feed log cells.

Bill, if you have both antennas on the ground, I would suggest this. 
Individually pull the driven elements off of the good antenna. Raise each 
element 20 feet or so off the ground and measure the vswr on each band. Now 
do the same thing with the one that's not working right.

Once you identify the element that's out of kilter, you can start looking 
for the problem (probably in the outer trap - possibly an aluminum shaving 
shorting the inner 3/8 inch tube to the exterior capacitor tube).

Once you get it down to an individual element, I'd recommend removing the 
shorting bars and do a resistance check beetween the innter tube and the cap 
tube.

Knowing how good the new design with the machines shorting bars is, I 
seriously doubt your problem relates to the problem with the KT34 series 
where the shorting straps develop crud leading to resistance.

One last thought, is there any chance that water got into one of the tubes? 
That leads to a question to satisfy my own curiosity. Assuming you built the 
KT34XAs you used in Fla, you know how tough it was to pull the capacitor 
insulators over the 3/8 inch tubing. Did you find it equally difficult to do 
this when you built the KT36XAs?

The reason I ask is because when I did the KT36XA upgrade to my 34, I found 
that the caps on the newly dimensioned rear driven element and reflector 
easly slid onto the 3/8 inch tubing. When the antenna first went back up it 
looked great, but aftere the first rain the vswr curve went to heck. I found 
water in at least one of the cap tubes on the rear driven element. It almost 
seemed like the 3/8 inch tubing supplied for those new rear elements was not 
quite spec. I tried a few different things to seal them with no success. 
Ended up punching drain holes in the bottom of the tubes and haven't had  a 
problem since.

In general I'd look for either a short or water in one of the cap tubes.

73 de Lar K7SV