On Tue, 02 Jun 2009 01:59:43 -0700, Roy Lewallen
wrote:

Again, the typical SWR meters we use do *not* measure the SWR on any
transmission line, except (indirectly) the SWR on the short line within
the instrument -- if it even contains such a line, which some don't. I
don't know of any way to directly measure the SWR on an intact coaxial
line, only on a slotted line.

The SWR on a coax line can readily be calculated, however, from
measurements it is possible to make.

Roy Lewallen, W7EL

The possibility of common-mode current on the outside of the braid has
been mentioned, but nothing has been mentioned concerning whether a
balun is used if the feedline-antenna connections is unbal to bal. If
there is no balun where should be one, seems to me it's a no-brainer
that the problem is common-mode current causing the different SWR
readings with different lengths of feedline.

Walt, W2DU