On Fri, Apr 04, 2008 at 01:37:33PM +0000, K1TTT wrote:
> Take a look at the picture of the tool next to a pencil for size comparison:
> This tool was uniquely suited for one particular job while disassembling an
> ice and wind damaged 40m4lldd yagi. Out of all the tools in all my various
> tool boxes this one stood out for this one specific task.
> Can you identify:
> 1. What it's original purpose(s) were?
> 2. What it would be used for in a 40m yagi disassembly?
1. Paint can opener
2. Opening a cold, frosty bottle of beer?
> Pictures of the 40m damage in progress are below... We had 3 ice storms in 2
> weeks, 2 of them were followed immediately by strong winds. Besides damage
> to both 40m4lldd's there were several bent elements on 20m4dx yagis that had
> survived several years with 'normal' ice and wind. Something interesting to
> note is that the loading rods on the 40m4lldd's did not provide any
> mechanical strength to the elements even though they look like they would
> act as trusses. The elements all bent on the same side of the antennas
> because the wind hit them from the side while the element was already bent
> down under the ice load. The same mechanism damaged all 4 elements of the
> top fixed European 20m yagi that was sideways to the wind, while the
> rotatable one above it only had 1 slightly bent element since it was
> pointing into the NW wind at the time. The loading rods broke all on the
> same side because the wind shifted while the elements were bent so one side
> of the loading section was stretched against the side of the element.
> Tower is 180' of Rohn-55 with the 40m4lldd's on ring rotors at 70' and 170'.
> 2/2 Top 40m with ice and wind
> 2/2 Top 40m with ice, note how on the left side all 4 elements are bent at
> the sme place and the loading rods are below the element tubing.
> 2/2 Top 40m with ice element closeup
> 2/2 Bottom 40m with ice
> 2/7 Top 40m with ice and wind, round 2 of the storms you can see the 1st
> loading rod broke on the right element. Eventually all 4 elements ended up
> with 1 broken rod, all on the same side.
> 2/7 Top 40m with ice and wind, slightly crooked elements.
> 2/7 Top 40m broken loading rod closeup
> Removal of the damaged antennas was done by XX-Towers on 3/7:
> Rigging bottom 40m, tram line is cable coming down to left.
> Bottom one coming down
> Bottom one wide view
> Closeup of broke loading rod end, its really not pulled out, the shorting
> bar held and the rod broke. The ss saddle and eye arrangement on the philly
> cable is my modification to prevent the philly from being cut on the side of
> the small holes it used to go through on the shorting block. M2 has
> modified the design with a strain relief to prevent that on new ones.
> Rigging the top 40m, tram line is hard to see but comes down between guy
> wires toward bottom.
> Rigging top, wide view.
> Liftoff of top one.
> Top one starting down
> Interesting rigging, use ring rotor supports and boom brace to spread load
> to 4 points on boom.
> Insurance has already paid off and I am awaiting delivery of a new 125mph
> 40m4lldd for the top. For the bottom one I salvaged parts from the top one
> to make it whole and have purchased aluminum to beef it up similar to how
> the 125mph elements are done. I also am waiting delivery of a 20m4dx to be
> used for parts to replace bent element sections on those antennas.
> Of course I am writing this today because we are now getting snow/freezing
> rain/rain/whatever out there and I figured I can wait a while to continue
> David Robbins K1TTT
> e-mail: mailto:email@example.com
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
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Kenneth E. Harker WM5R
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