K7LXC@aol.com wrote:
>
> In a message dated 98-12-16 17:36:20 EST, you write:
>
> > I can tell you all the things NOT to do.
>
> Why don't you post it so we'll all be smarter?
>
> Cheers, Steve K7LXC
OK, for what it's worth.
Well, when I started doing the refurb on the TH-3, I just tried
to do it as fast as I could. Some of the guys on the reflector
told me to take the traps apart, but Roger from HyGain told me I
shouldn't do that. .
So I didn't. I just cleaned the elements up and put some Ox-Gard
(WAY WAY too much) on the connections. After I put it back up,
the SWR kept changing all the time. One morning it would be
working right, then it would rain and the SWR points would drop
clear down below the band edges. After fighting it all weekend
during the contest, I took it down Monday and started all over
again. I found the Ox-Gard had become contaminated with water
and it was really messy!!!
The traps came apart very easily. Just one screw to remove and
slip the covers off. One other thing I noticed was that some of
the screws holding the covers on weren't all that tight. When I
retightened them, the screw wouldn't tighten down as tight as it
should. On those traps, I put in a little bigger screw and they
tightened right down.
When I did get the traps apart, I found they were full of all
kinds of junk. Spider webs, spider eggs, dead critters. I used
a baby bottle brush to clean the inside of the trap covers.
Worked slick. The wires in the 10, and 20 meter traps are
aluminum. The 15 meter driven element traps are made with copper
wire. Where the coil wires were connected to the elements,
corrosion was very bad. The screws used to hold the ends of the
coils down are made of steel. I couldn't figure out why the heck
they would use steel screws to hook aluminum to aluminum. When I
disconnected the wires, a powdery substance came out from under
the connections. Aluminum oxide is a very poor conductor. After
I put the screws back in, I covered each one with a small dab of
Vaseline to deep them from getting so corroded again.
When I put all the elements back together again, I took some
Ox-Gard and worked it into the aluminum with some emery cloth.
After I worked it in good, I wiped the excess off the tubing so
there was just a film of anti-oxidant on it. That is the way I
was told it's supposed to be done.
I put the antenna back up Tuesday, and so far, so good. The SWR
points are just where I want them and it is working real good.
The main thing is to be sure to get inside the traps and clean
them up real good. Inside the covers, and especially under the
coil wires where they are connected to the elements. 73 and good
luck on the rebuild.
Tom W7WHY
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