Don,
I have a TH6DXX that is very old now. 30+ years and I am the second owner.
I also have another that is in the barn that was up for 26 years. I rebuilt
both of them before putting them up.
To do the traps, you have to [almost] beat the aluminum cover off, as they
are not made to take apart. I was successful in redoing all the traps on
both antennas. One issue is that they tap a punch on the cover into the
insulators.
Basically what I did was replace the screw that connects the coil to the
element on both ends with stainless steel, clean well and coat with a clear
lacquer. I also put new black plastic end caps on the traps and covered
them with good electrical tape to help preserve them, which worked very
well. I also used just a small amount of silicone glue where I installed
the black end caps to keep moisture out especially if the end cap
deteriorates.
Around here we have spiders or other bugs that build grass nests in the
traps and when it gets moist it starts fires in the trap and eventually the
insulators turn into a big carbon path to the element.
There is a method to putting them back together, and I may not recall all of
it after all these years, but the problem is getting the insulators back in
the right spot inside the trap for mechanical support. As I recall, I
somehow used a long round piece of wood (doll rods) to tap the inner
insulators into their correct place from each end, and then follow up with
the outer most insulators and finally the end caps.
I wish I would have installed the TH7 upgrade kit when I rebuilt them for
the bandwidth. My Alpha 87a doesn't like the VSWR at the band edges and the
solid state amps likely don't either.
I do have an NEC model of a TH7 if you are interested; I got it from someone
else some time ago, so I can't vouch for its integrity.
Jim - KR9U
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>>> If this is NOT the appropriate site let me know. I?ve some technical
questions re this antenna I asked HyGain and the answers appear to be
guesses. Since they did not design it but only manufacture and sell it I
probably should not be surprised.
Is there a blog or reflector dedicated to this antenna or does anyone know
of someone that has done an engineering or technical analysis of the
antenna? If so, I?d appreciate passing this along to me.
Also would like to connect with someone who has pulled and repaired TH7
traps. While I had to do this many years back, I have a couple of questions
(poor old brain doesn?t remember a couple of the details).
Don W7WLL
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