>
First of all Grian, don't assume anything. 3/4" hardline is big enough
for you to measure the od of the inner conductor, and the id of the
shield. Then get out your handbook and plug the figures into the
simple formula they supply. You also need a dialectric constant, but
in reality, just choose a similar one from the information given. You
will then know whether the stuff is ~70 ohms, or you may get a pleasant
surprise and hit the jackpot.
<
I have some specs on CommScope P3 750 which is 75 ohm cable. The ID of the
shield is .68 and the OD of the conductor is .167.
Zo = 60*ln(D/d) / e^.5 where D=.68 and d=.167 gives 51 ohms not 75 ohms. Do I
have the wrong formula (or bad calculator)?
Thanks, Pete ws4g brunet@us.ibm.com
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