Cec,

Alternatively, place orders for one or two reels of coax with all USA,
Japanese, Chinese, Korean, German, French, Russian, British cable
manufacturers.

When your back yard is stacked high with full cable reels, cut off a
measured length of cable from each real, lay them in straight lines on
the ground and measure the velocity factors using a hand-held antenna
analyser at around 10 MHz. You will also need a good steel measuring
tape and a sharp cable cutter. Don't use an axe!

Discard outliers of the distribution - they are probably faulty. Use
your pocket calculator to find the average, max and min, and the
standard deviation and you will have the answer to your question.

Then set up a shop.

But I'll save you the trouble and make an uninformed guess. The
Standard Deviation will be around 4 percent of the VF with the 3-Sigma
limits at plus and minus 12 percent.
----
Reg.