On Sat,11/8/2014 10:14 AM, Dick Green WC1M wrote:
Thanks, Jim. Could you summarize the procedure (e.g., measure the cable open
or shorted) and arithmetic for me?
k9yc.com/Coax-Stubs.pdf
Put a connector on one end, connect to the analyzer, leave the other end
open, vary the frequency of the analyzer until you see a null (near zero
ohms). That is a quarter-wave, or some odd multiple of quarter waves.
Or short the other end -- then the nulls will be at multiples of a half
wave. Measure the physical length, compute wavelength at the test
frequency, divide that by the free space wavelength and you've got Vf.
Example a free-space quarter wave on 80M is roughly 67 ft and is the
lowest frequency null you measure, the length of the sample is 45 ft, so
Vf is 45/67.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|