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[TowerTalk] N connector impedance

To: <towertalk@contesting.com>
Subject: [TowerTalk] N connector impedance
From: brunet@us.ibm.com (Pete Brunet)
Date: Tue, 7 Jul 1998 18:09:00 -0400
Hi, I want to know whether to use 50 or 75 ohm N connectors on some hardline.
First some background might be helpful.

As part of building our antenna system we are using some existing 3/4 inch
hardline that was previously used in a satellite system many years ago.  I
assume this was a receiver system, but it is possible that it could have been
used for transmission too.  We assumed this is 75 ohm cable, however using a
TDR shows a value close to 50 ohms and using a micrometer and the formula Zo =
60*ln(D/d) / e^.5 where D=.675 and d=.165 gives 51 ohms.  The location of our
radio room is not the same as the satellite room so we had a contractor run
cable over to existing hardline and patch into it.  This new cable is 75 ohm.
(I wonder how much of a problem we are going to have if the original cable is
50 ohm?)

I assume we need 75 ohm N connectors at the radio end of this new cable.  Is
that a correct assumption?

Thanks, Pete

=====
Pete Brunet -- IBM Special Needs Systems, 11400 Burnet Road, MS 9448, Austin,
TX  78758
(512) 838-4594 voice, (512) 838-9367 fax, brunet@us.ibm.com, ws4g

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