An SWR that high indicates a feedline problem - either a
short or open somewhere. (Or trying to use a 2m antenna
on a different band.)
A quick test would be to measure the continuity across
the coax connector - if you are using a matching stub it
should look like a short circuit to a DC meter. Removing
the matching stub it should be an open circuit for DC.
(This requires that the driven element be split in the
middle.)
Perhaps the most likely problem if all else looks OK is
getting a good connection to the metal blade of the tape
measure. Sticking a wire under a hose clamp won't do it.
My prefered method is to scrape off the paint and solder
the coax leads directly to the inside corners of the
driven element. An alternative is to use a sheet metal
screw through the element and into the PVC fitting
(which needs to be pre-drilled.) I also scrape the
paint away from the hole and use lock washers with
Ox-Gard on the screw to maintain a good contact. (Oh,
and the hole needs to be punched, not drilled, or the
tape measure material will be weakened.)
My current assembly method is fiberglass-reinforced
strapping tape around the ends of the PVC couplers to
hold the elements on, plus one or two screws in each
element if they are doubled in the middle for added
rigidity. Since the driven element is not continuous,
I always use one screw in each side - this is convenient
for attaching the coax, but soldering is better for
long-term service.
Other than that, nothing in the general antenna should
give you such a high SWR. Generally I start with the
elements cut to resonant length, add the matching stub,
then trim the ends of the driven element for best match.
But even this shouldn't go over 3 : 1 at worst.
And, no, there is nothing magic about the length of the
cable that would cause such a high SWR.