Fujinaka-san,
The TH6 is a great antenna! You should definitely try to use it. But beware of
a couple of things:
1. It's a big one for roof mounting . . . be careful of obstructions and do
your best to BALANCE the antenna at the boom to mast clamp. This will make life
much easier on your roof mount and rotor and it will make it easier for you to
install.
2. The U-bolts may not be easy to find locally in stainless steel. There are
several sources out there - I use a company called FARMTEK for some. See
http://farmtekcatalog.com/c/g8/p/fullpage.php?page=t272&session=1001992 right
there on the page under Hog Brackets and Accessories. You can also order
replacement hardware from HyGain, but you will probably have to find out the
equivalent part number in today's TH7DXX manual, and you might have to wait for
delivery. Be flexible about the U-bolt sizes. Your trusty electric hand drill
may help you accommodate a slightly different U-bolt that's easy to find. Oh,
yes, when using stainless steel, be aware that the nut and bolt can seize when
tightened down. This is a common problem and best remedied with "anti-seize"
compound - easily available at your local Home Depot. It is silvery paste, a
bit messy, time consuming to apply, but it is well worth the time and effort
when you take that baby apart in a few years.
3. Do you have the manual and all the dimensions? I'm sure you can find an
electronic version of the manual from a friend here on TowerTalk.
4. Those of us who have had experience with tribanders at lower heights will
tell you a few things. 1) The tribander at any height above 20 feet will
definitely work better than the vertical, and 2) there's a BIG difference
between 20, 30 and 40 feet. You really will do better at 30 or 40 than at 20
feet. Can you swap the TH6 with the quad? That would be cool, and it wouldn't
hurt the quad performance at all, 3) beware that when your tribander is very
close to the house, its performance may be affected by metallic objects nearby,
like inside wiring, metallic gutters, and foil-covered insulation in the attic,
and 4) RFI in the shack can be a big problem when the antenna is that close. As
the number of wavelengths between the shack and the antenna decreases, you get
into more and more trouble. To deal with this, get the antenna as high as you
can, use a balun on the antenna [does the TH6 use a 4:1 balun?], and be
prepared to do some RFI reduction inside the shack. While these suggestions
definitely apply if you are running an amplifier, you can still experience
difficulties running barefoot. So, just beware!
5. This point should be noted FIRST. You might have electrical service
entering the house in the air on one of the corners. As you well know,
electrocution is never the goal, but occassionally the outcome. With such a big
antenna being waved around on the roof durning installation, that service entry
is a major concern. Be careful - real careful.
Great antenna! Great deal! Use it well.
73,
Jim Idelson K1IR
email k1ir@designet.com
web http://www.designet.com/k1ir
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