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Old November 5th 03, 01:41 AM
Tom Bruhns
 
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Leading eventually to the suggestion that perhaps your MFJ analyzer
isn't worth the powder to blow it up...

But I submit that you can make VF measurements on your cable with it,
which may be limited by the accuracy with which you can measure the
length of line you are looking at and not by the fact that you're
using a relatively inexpensive instrument. Here's one way. If you
look at a shorted stub 90 electrical degrees long in parallel with a
50 ohm resistor, you'll have to move the frequency by some value to
resolve a difference. The amount you have to move the frequency
probably determines the resolution you can get in VF. But if you make
the line 270 degrees long, you'll have three times the sensitivity.
So a hundred foot length of line, measured near 10 meters frequency,
would be long enough to get very good resolution--it'd be on the order
of 1530 electrical degrees. I'd be surprised if you had trouble
seeing the difference between, say, 0.664 and 0.665 VF. But beware
that the VF _does_ change with frequency, even over HF. There are
times when _I_ care about that, even if some others don't.

Cheers,
Tom

"Jason Dugas" wrote in message ...
Asswipe,

The question I posed wasn't "What's the velocity factor of ALL solid
polyethylene coax cable". Next time read the question and answer it. If
you don't know the answer then DON'T POST A REPLY!

Too many ignorant people in these groups anymore!

"Reg Edwards" wrote in message
...
The velocity factor of ALL solid polyethylene coax cable, regardless of
impedance, is 0.665




 
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