[TowerTalk] Boom stress with ice @ K8DX

[Jim White, K4OJ]

Scott......I saw the pictures, sorry but - you now have an opportunity to
do it even better.  I am happy to see you enjoying this as a
challenge...this is a side benefit of having a competitive radio station,
the satisfaction of doing the station engineering to the degree that you
feel really good about what you built.




"On 20M it is over 3,000#. Because the antennas are all on rings, I like
the simplicity of only a single overhead truss."

Agreed, the single truss is neat, and simple - as Leason points out it does
not aide in sideways forces but will compensate for the downward weight of
the ice (what's ice - oh yeah that stuff in the freezer that you put in
your Screwdriver)


 




"What I'm a little curious about is what kind of turnbuckle to use to take
these forces, short of what I'm using to guy the tower."



I have used forged turnbuckles for trusses a lot of times since they had
been "on-hand" form purchases at the flea markets over the years......yes,
they are overkill usually - but that certainly beats using a bent eye
turnbuckle which will open up when you least desire it!  Sure if you buy
them new they are bucks.....but for boom trusses with patience you can
amass them in flea market visits...heck you are an 8 - you have the
Hamvention in your back yard!







"Is anyone not using turnbuckles and "hardwiring" it to length and leaving
it? "


This past week I put up a sidemounted beam and had the ground person, I
think it was W1CW, suggest I use the work rope to get the truss taught and
into position, after I bolted down the boom to mast attachment....for some
reason this had never occurred to me before...I always have done it but
sliding the common point up the mast until the slack was gone and then
turning the turnbuckles til the boom was taught.  I had a ground guy
pulling on the work rope which went above the antenna through a pulley and
back down to the plate my two turnbuckles went into at the truss' apex. 
The ground guy got on the rope so much that I had very little turnbuckle
twisting to do to firm things up.  



Based on this experience I would recommend you attempt going without the
turnbuckle if you can use wire rope clips at the top of each side of the
truss...why?  Without the turnbuckles if your lengths are not right on the
money you may need to do a fine tuning of the length adjustment. You need
to be able to have equal pull on both sides which translates to having
correct lengths if you bring both to a common support point.  You can then
use something like a comealong to tension the truss' central point, and
while under tension pin down/attach/tighten the u-bolts on  the top of the
truss.  





BTW, all the trusses will be Phillystran.

......but of course......you are building the ideal station, eh?


GL!   If your station is not done by Thanksgiving I may know a band that
needs manning :-)




73,


Jim, K4OJ
k4oj@ij

One  month until Sweepstakes CW, make sure you work me so you will not miss
the elusive South Floirda multiplier!


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