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.

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?

Ken KC2JDY

I've found this method to be very ineffective in choking common mode
feedline current -- an effective sleeve requires a high impedance for
the outer coax structure, which this doesn't provide. So your dipole
impedance and performance will depend on the length and orientation of
the feedline and the ultimate path to ground for the common mode
current. You'll probably need to trim it when connected to the rig
you'll be using, grounded (or not) as it will be when used.

Roy Lewallen, W7EL