tensioning method for secondary?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Laurence Davis by way of Terry Fritz <twftesla-at-qwest-dot-net>" <meknar-at-hotmail-dot-com>

i just wrapped another secondary.  22awg on PVC/sch40 4" pipe.  i don't have 
a coiling jig. its more like the pipe rests on my ankles and i spin it for 
about 3hrs.  BUT when i place the secondary in the basement
to let it 'acclimate' to the temp before i poly it, it loosens.  therefore i 
assume the temp exp coeff of pvc vs copper is that the pvc contracts faster 
than the copper per degree.  instead of this being a problem, i decided that 
i would use it to my advantage.

cool the coil in a walk-in freezer, while retensioning. when coil is 
retensioned in the cold air, when moved to the warm air... voila nice tight 
secondary.  i'd like to compare the temp coeff to see if i can calculate how 
much temp change the copper can stand till the stress causes the copper to 
either stretch or break. but i'm not sure how to convert the "coeff of 
linear thermal expansion" to a cylinder expansion.

retensioning before poly is a pain, perhaps i just need to make a jig to 
wrap unattended -and- tensioned.

larry d.

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