[TowerTalk] KT34XA

[Jeff Singer]

Hi Rod,

You might try adding random lenghts of coax to the existing coax. It's
amazing what a "bad" length of coax can do to your swr.

I once bought a used 'xa too. The thing was one of the very early ones,
maybe fifteen or twenty years old or more. It had been converted from a
kt34-A. The owner sold it because he couldn't get the swr to be
acceptable.

When I started to work on it, I found MANY of the dimensions off by
"only" a half-inch or so, not to mention that some sections were
actually fused together from time. The antenna was actually black from
soot and weather.

So as not to take up too much bandwidth, I'll just say that I had this
antenna up and down the tower more than a dozen times (conservatively)
before I got it to work right. In the end, all sections and connections
had to be scrubbed and polished (no getting away with anything here),
all tubes had to be cleaned out (they are notoriously desirable insect
nests), and the whole thing re-spec'd.

It became a wonderful performer, just had to be treated right. The swr
was perfectly flat EVERYWHERE, and then some. And it had the best set of
ears I've ever experienced. Unfortunately it eventually came down in a
windstorm and was badly damaged. It has since been resurrected
(repaired) and today it is only a '34A, but still performs beautifully,
low on the tower, fixed to Europe.

I hope the balun solves your problem, but I'll guess that there's
another problem, like water droplets in one of the tubes, or, again, the
length of coax. You might also try creating a coax "choke" by wrapping 6
- 8 turns of coax into a loop around 6 - 8 inches in diameter, and
taping it all together. You can do this on the shack end. Might make the
difference.

Good luck.

73 de Jeff K2KV
k2kv@netusa.net 
--------------------

Roderick M. Fitz-Randolph wrote:
> 
> Jeff, I have virtually the same sort of SWR problem with a KT-34A.  I
> have checked, double-checked, and rechecked.  I have a test balun on
> the way because both Bruce Scott and I believe that it may be the problem.
> To wit, the MFJ-259 indicates (by way of the SWR changing dramatically
> when my hand gets close to the chassis of the MFJ-259) that the coax in
> some way is radiating.
> 
> I've tried changing the coax and I've duplicated the SWR that the MFJ-259
> indicates when I've hooked up the TS-940S to the antenna and checked it
> for SWR with 5 watts feeding it..... same-same.  It is really baffling.
> I'm hoping that the balun is the answer.  Then I'll be able to put it up
> and use it for the upcoming contest weekend.
> 
> By the way, it was a used unit that I bought for $250 (it have been up for
> 3 months) and I found many dimensions wrong and even the spacing of the
> elements was incorrect, however, I changed all dimensions and spacing to
> that of the manual's specification and still rotten SWR.  I'm baffled.
> 
> Rod, W5HVV

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