Re: [TowerTalk] Speaking of wood supports

[Don Havlicek <n8de@thepoint.net>]

When I was in college [before electricity, it seems], I built a 
fold-over tower of 2 12-foot long 4x4's and 2 18-foot long 2x12's.
The first 4x4 was put in a hole approximately 4' deep and the two 2x12's 
were lag-bolted to that piece.
I drilled a 1-inch diameter hole in the two 2x12's approximately 6 
inches from the other end of them, and inserted a 1-inch bolt through 
them and the mid-point of the other 4x4.
Using the second 4x4 as a 'push-arm' and a stout rope, I rotated the 
assembly upward and placed a second 1-inch bolt through the 2x12's and 
the 'ground' 4x4 to hold the entire assembly erect.
Having previously mounted a rotor-bracket and thrust bearing on the 
upper 4x4, I was then able to allow it to turn downward, using the 
weight of those brackets, inserted a mast through the bearing and into 
the rotor ... climbed a short ladder and tightened the mast in the rotor 
... then, mounted the 5-element 15m yagi I had assembled [upside down!] 
to the mast.
Pulling on the stout rope [still attached to the far end of the upper 
4x4, I was able to rotate the entire structure to operating position.
Yes .. I had previously mounted a piece of 2x8 to the [now] lower end of 
the upper 4x4 to prevent it from 'over-rotating'.
This 'tower' put the 15m yagi approximately 23 feet above ground, and 
provided me with a lot of DX for a few years .. until the entire thing 
came crashing down when 80+ mph winds hit one Spring day ...
Makes me smile to think of what we were able to manufacture when we 
couldn't afford to buy something more permanent!
Don
N8DE

Tower (K8RI) wrote:
> The note on  using a wood Gin pole jogged a very old memory.
>
> Wayyyy back when I was first licensed, I built a simple A-frame out of 2 
> X 4s (when they were really 2X4s). It was multiple layers for 
> reinforcement and was about 30 feet tall (as I recollect)
>
> It hadn't been up all that long. Maybe a few weeks when we had a pretty 
> strong wind. Out there in the flat lands there isn't much to slow it up.
>
> I was operating on 75 when I noted a low frequency hum.  I couldn't find 
> what was making the noise, but it was one that seemed to penetrate right 
> through me.
> I happened to look out the window and saw the A-frame vibrating like a 
> tuning fork. It was moving so fast you could see the standing waves.  I 
> was looking right at it when it let go.  It sounded like a 12 gage 
> shotgun.  The largest piece I found was less than 3 feet long.  As I 
> recall, some of those pieces flew over 50 feet.
>
> I don't think I'd want to use wood for a Gin pole except for very light 
> duty.<:-))


_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk