Chevy454 wrote:
I want to make a flexible, portable, vertical 10M dipole from coax by
folding back roughy 1/4 wavelength of the sheath and taping it in
place.

Be careful about the end of the coax sheath where the
voltage can reach levels high enough to arc and/or
give severe RF burns.

I would not expect the sheath to perform like an equal length of solid
or stranded wire because if the extra length of wire. Is there any
theoretical way to compute a factor, or do I just keep snipping until
I get lowest SWR at the desired freq?

A web page gives 460/f for the overall length. I would
use the standard 468/f and trim to resonance.
--
73, Cecil http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein