[Amps] crossmodulation in PA ? Thanks for all good  advice

[Roger]

>I don't quite see where you get "tens or hundreds of thousands of pounds of
>pressure" on joint bolts on a typical ham tower? The towers are not that
>heavy. Joints can easily move especially on smaller towers as the wind
>blows. Watching joints on a self supporting tower is interesting as it 
>moves
>in the wind.

What is the contact area for the bolt and tower load bearing surface?  On a
tower leg with a 16 gage tube  you are only going to have a surface area of
of say 0.25" X 0.0625 (16 gage for 25G)" or 0.015625 sq inches per bolt even
with 30# per section a 50' tower would weigh 150# with nothing on it.  If
all three legs bear the load evenly that is 3 * 0.015625 or 0.046875 sq
inces supporting the whole tower. At the bottom of the tower that is 0.0469
sq inches supporting 150# or  or 3,200 pounds per sq inch.

>heavy. Joints can easily move especially on smaller towers as the wind
>blows. Watching joints on a self supporting tower is interesting as it
>moves
>in the wind.

With the joints moving then only one or two bolts may be holding the entire
load at any one time which would increase the load per sq inch dramatically.

<snip>

73

Roger (K8RI)