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TH6DXX Issues

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Subject: TH6DXX Issues
From: (Don Gaikins)
Date: Mon, 06 Jan 1997 17:50:58 -0600
At 08:52 AM 1/6/97 -0600, Lee Buller wrote:
>Ladies and Gentlemen...
>I just purchased a pristine TH6DXX for $150 dollars that included new trap
>caps, and stainless hardware set still in the bag.  The beam has been in the
>garage for the last ten years and was up in the air for about eight years.
>I would like to know the following.
>1.  What are people using now for a substitute to the BN86 balun?  I've
>never like these baluns since they have a tendency to fry.
>2.  Being a CW, RTTY and SSB operator, what is the best setting to use?  Low
>3.  Does Hy-Gain still sell the TH7 conversion for it?  I've done this once
>back in the early 80s for $140 bucks.  But the thing broke in an ice storm
>and I sold it off and got a smaller antenna.  This might answer qustion 2.
>4.  I have a Ham III rotor which I have used before with the TH6.  I am
>sending it off to have it reworked and a heavier brake installed.  I'm don't
>want to mount the rotor ten foot down in the Rohn 25G tower like I did
>before.  (The tower is 60 foot, guyes at 35 and 55 feet with a pointy-top.)
>I had to cut the rung in the tower to fit it in, I don't want to do that
>again.  Can the rotor be place high in the tower where it fits using a
>shorter mast?  I do not plan to place a 40 meter beam ontop of the TH6.  I
>plan to put up a small six meter beam and a KLM two meter beam for SSB and
>CW.  The TH6 will be about 12 inches above the top of the "pointy-top" tower
>section.  I know that some of you have placed the rotor ant the next section
>down and used a thrust bearing where the rotor usually sits.  Comments on
>the above would be appreiciated
>Please respond directly to me, so minimum bandwidth is taken.

Lee, I had a TH6DXX for many years and loved the antenna.  One thing that
you must remember about that antenna is that the traps and the BN86 balun
were designed when the legal power limit was one killowat dc INPUT, not 1500
watts OUTPUT.
When I used the antenna, I had an SB220 amplifier.  The beam was tuned for
low phone.  That gave an acceptable swr over all of 20 meters and most of 10
meters.  But on 15 meters the swr was over 2.5 in the bottom of the cw
portion of the band.  In the phone section it was under 1.5

I then got another amplifier that would output the current limit of 1500
watts.  One evening when trying to work a dx station, while loading the new
amplifier, the swr went to infinity!  Well that was the burning of the 15
meter traps on the driven element.  I found when I took the antenna down
that the cores were like charcoal!

I had replaced the BN86 balun with a W2DU balun.  It was unharmed.  But I
think that I would rather fry the balun (which you can replace with out
taking the antenna down) then the traps.

As of 1989 Telex High Gain still sells an upgrade kit for the TH6DXX to make
it a TH7DX.  It was very expensive when I was looking into it.  My solution
was to purchase a used KT34XA that I found localy, for less money then it
would have taken to up grade the TH6.

Good luck

Don Gaikins

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