"Kristian Ukkonen" wrote in message
...
On 2/22/2012 8:29, RogerN wrote:
My most immediate use will be to tension the guy wires on the
antenna tower
I'm preparing to put up and later hopefully to do tests on
construction of a
homemade crane. I'd like to verify/test my force calculations to
keep the
design factor correct.

Isn't the normal way to measure tension of wires by attaching a
gauge to measure the elastic deformation (increase of length by unit
length) of the wire by the force? Basically a long caliper attached
to the wire say 30cm apart.. Same is used to measure tension of band
saw blades too.

The elongation is two parts per thousand at the (arbitrarily) defined
yield point of steel.
http://www.keytometals.com/Article53.htm
Right above "Ductility".

This small amount is difficult to measure accurately in the field,
like on a steel cable guy line, being only 1mm per meter at a 2x
safety factor.

jsw