The order in which the sections come up is not controlled by any mechanism,
the motor just rotates the drum in the direction to push the nylon cord up
the tube. The cord is attached only to the center (smallest) section, so if
there were no difference in friction on the various sections, which section
comes up first would be purely random. Since the center segment has the
smallest contact area with its sliding surface, it would be the one to come
up first if everything were perfect, but the difference is quite small. On
an antenna with even a slight coating of crud on the inner section, it will
be the last to come up, if the other sections are clean.
The clutch begins to click when it senses any obstruction to motion. If
the clicking starts before all three sections are up, there must be a
restriction somewhere. I think you're best bet is to have someone hold the
"up" switch while you assist the center section. If the obstruction isn't
too bad, you will be able to help it past the damaged place. Once you get
it extended to where you can see the damaged place, you can decide whether
or not it is possible to straighten or otherwise mitigate the friction
enough to make it able to extend on it's own power. If you can't get it to
extend all the way, even with a strong helping hand, I think you are looking
for a better antenna. Sorry.
It is possible that your cord has been shortened - sometimes folks will do
that when the cord gets damaged and they're too cheap to replace it. If
your antenna will go up to 31" above the fender, this is the optimum point
for FM reception anyway.
You can remove the mast assembly (with cord attached) and take the mast
apart by unscrewing the cap button on the tip, then pulling the cord and top
section out the bottom as a unit. Of course you need to grip the center
section with a leather coated vicegrip or vise, then grab the button with
another similar tool to avoid damaging the chrome. Some times the top
button is really on there tight, be prepared for a fight!
With the center section out of the way, you might be able to get a look at
the damaged part of the section which is sticking and possibly tap it back
into shape. You might even be able to see the damaged place without going
to all this trouble, if you can get it all the way up one time.
Since it sticks right where the middle section is about to start its travel
up the outer section, I suspect the trouble is right at the bottom end of
the middle section. There is a sliding phosphor-bronze contact that rides
on the middle section to maintain good RF contact with the outer section -
if it is damaged such that it cannot slide into the outer section, you will
have to fix that item or give up on this antenna mast.
Dick Benjamin (not an antenna mast-er)
----- Original Message -----
From: "Mark McDonald" <tomswift@xxxxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Friday, April 18, 2003 12:23 PM
Subject: Re: IML: 67 vs. 68 antenna
> I hope this is not boring the heck out of everybody. Maybe one day it
will help
> you with your own antenna problem . . .
>
> Anyway, I took the old antenna apart and I can't see how the dent in the
sheath
> could cause a problem. There is a gap b/n the wall of the sheath and the
> antenna itself of about 1/4"-- if it was dented in enough to obstruct the
> movement of the antenna, it seems that the antenna wouldn't move at all.
>
> Yet the thickest part of the antenna moves freely. To explain, the
antenna is
> in 3 sections. A thick one containing 2 slightly skinnier, or thinner,
ones.
> The way the antenna comes out of the fender, the thickest section comes
out
> first, followed by the skinniest, followed by the middle. When the middle
one
> is about to come out is where it gets stuck. Then you hear a clicking
sound,
> like it has hit the end of its extension, or has hit some obstruction and
the
> clutch in the motor is slipping.
>
> I just realized this is not the way I remember these antennae working.
Usually,
> they come up like this:
>
> top part (skinniest)
> middle part (next thickest)
> last part (thickest; the part at the bottom)
>
> Again, sorry to go into such detail but it's bugging me.
>
> Mark
>
> Mark McDonald wrote:
>
> > Dick, yes, I'm talking about the tube, or sheath, that the antenna
itself is
> > in. Not the motor housing. It appears as if it came from a car that
was hit
> > in the fender there and it bent in the tube a bit (about 1/2" maybe),
but the
> > antenna itself is great.
> >
> > I have removed every bolt on it I can and the sheath won't budge. Is
there
> > some trick to getting the sunuvagun off?
> >
> > Thanks, Mark
> >
>
>
>
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