[TowerTalk] Info on tilt plate latch

[Richard (Rick) Karlquist]

I have received many requests for drawings.
It occurs to be that there are numerous photos
of my tilt plate latch up on www.n6rk.com, but
there is no description of the latch to clarify
how it works:

1.  There is a mechanical "toggle" mechanism
utilizing a spring.  The spring will hold
the latch either open or closed.  (I happen
to think this is actually fairly clever).
Nothing depends on gravity.

2.  Before raising the tower, I manually
push the latch into the open position.

3.  I then thread a piece of rope through
the "eye" at the outer edge of the latch,
and pull the rope through so that I have
enough rope to have both ends go out 25
feet or so.

4.  When the tower is about 2/3 of the way
up, the hinge will naturally by gravity,
make contact on the stops.

5.  I then stop the winch and pull on both
ends of the rope to close the latch.  This
wedges the notch in the moving plate under
the head of the bolt.  Notice how I have
"sharpened" the notch area to get a tight
fit.  A lot of force can be applied with
the rope to seat the latch.

6.  The toggle spring keeps it in it this
position.

7.  Now I can pull on 1 end of the rope and
pull the rope all the way through the eye
so that is isn't hanging from the eye when
the tower is raised.

--------------------

To lower the tower, I lower it maybe 20% to
where the flexing of the MonstIR working
with gravity will keep the hinge bottomed
out, and there is no danger of the Yagi
flipping over.  I then use a 24 foot aluminum pole to
push upward on the eye bolt and get the latch
into the open position, where the toggle
spring will keep it open.  Then I complete
the lowering process and the hinge starts
to open on its own.

The ends of the elements will try to impale the
ground, so some manual "supervision" needs to be
applied to level out the Yagi.  This has
nothing to do with the latch per se.  It's
just for general information.  I have a remote
winch switch so I can have it in one hand
and have the other hand free to tilt the
Yagi.


I have repeated this process many dozens of
times without any problems.  The latch holds
the tilt plate rigidly with no wiggle room.
Wiggle room is one of the worst things you
can have in an antenna support structure.
It is not necessary to put side guys on the
boom of the MonstIR like it is with the
Karlock.

I don't have any mechanical drawings for the
latch, just the photos.  I built it from parts
at the local hardware store.  It is fairly
obvious once you see it.

Rick N6RK