Ian White GM3SEK wrote:
. . .
Coaxial cables with braid-over-foil shielding have a generic problem
that if they're bent too sharply, the foil will tear into separated
segments each about an inch long. The cable then relies on the braid for
overall shield continuity. It will still function, especially at low
frequencies, but there isn't much contact pressure to maintain the
continuity between the braid and the foil.
. . .

Most interesting! The cable I've been measuring has been kept in a coil
of about 3 feet diameter, but squeezing and handling it has reduced that
to probably about a foot or so at times. But I don't recall the coil
size when I received the cable, and of course I don't know anything
about how it was handled between the manufacturer and delivery to my
home. This might be an explanation for the variablility. I did hear from
someone else a while back that he'd seen variability in a foil-wrapped
cable, but I don't think it was specifically Bury-Flex. I have some
RG-58 size cable with the same general construction which doesn't show
this variability. But it looks like the stress would be worse on the
foil in a larger diameter cable. Also, there seems to be some difference
in how the foil is more-or-less bonded to the PE, and that would also
play a role in the stress.

I want to keep the piece I've measured intact for the time being, but if
I get up the time and interest to do more measurements on another piece
of cable, a post mortem might be revealing.

Roy Lewallen, W7EL