6 meter Duplexer Project for the K5JMP Repeater
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September 5, 2003 Update
The lay-down tower project has been by slowed tons of rain over the past few weeks. But, I am happy to announce some progress. I have almost completed the upper portion of the hinge assembly.
It was not what I had in mind at the beginning.... but should serve the purpose. The hinge it's self is constructed from 2" x 3" x 5/16" angle iron. I used 1" grade 8 hardened bolts for the actual pivot, and the tower attachment tabs were salvaged from the old base. This plate was also salvaged from the original base... it is 1/2" plate, with 1" bar stock added to help stiffen it.
Although not in sharp focus... this picture should give some idea of how the pivot is constructed. It also shows how you cannot buy the "good Rustoleom" in the state of Virginia.... you have to go to Maryland. The hinge was in the rain only for a few days and is already rusting, with four heavy coats of cold galvanizing spray... guess I will sandblast it when completed so it can be "hot-dipped".
As always, Casper was around to lend morale support.. as long as I am
willing to toss his tennis ball every once-in-a-while.
A little better focus on the pivot, and more rust.
Another view of the pivot, and rust.
Hinge in the "tower-down" position.
I was also very careful to align the hinge to allow the tower (with careful
support) to be extended in the down position.
Please notice the distant gate.
This photo also shows where the traveling nut is to be mounted. The washers
need to be trimmed to clear the welds... and a safety nut will be placed on the
bolt located inside the rail. I will have to drop the plate approx 2" and
re-level to accomidate the safety nut.
I will also have to trim the plate to make room for the stationary nut and
motor, to be mounted on two pieces of angle attached to the bottom of the
plate. I was given a "lead screw" that was threaded with an
"Acme" thread. This screw was donated by AK1E (Mr. Thomas Harmon).
Tom had originally been using this screw on his 100'+ Heights Tower...
unfortunately, it was a little too much for the travelling nut to survive. The
heat and friction generated by Tom's setup was tremendous!!! In fact, Tom
"boiled" the nut and it was siezed to the screw when I received it
from him. A ton of heat, and an impact wrench (of the large variety) were
reqiured to free the nut. The damaged thread portion of the screw was cut off,
as it was much longer than I required.
I did locate "machinable" blanks threaded for 1" Acme. Supplies
for this project can be purchased from McMaster-Carr, a pdf of the pertinant
catalog pages (file is a little over 3mb) can be viewed here.
More as I get "a round tuit".
More progress to report 09/07/03
73's de K5JMP
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