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Re: [TowerTalk] LMR-400 LMR-600 Equivalent (and stuff)

To: "'Kevin'" <rkstover@mchsi.com>, "'Roger \(K8RI\)'" <K8RI-on-TowerTalk@tm.net>
Subject: Re: [TowerTalk] LMR-400 LMR-600 Equivalent (and stuff)
From: "James Wolf" <jbwolf@comcast.net>
Date: Wed, 4 Jun 2008 19:45:06 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Kevin,

I agree.  We tried using Cat5/e on a 1 GHz link that had to run at 1 GHz or
it would lose sync. We couldn't get anything even close to reliable beyond
about 12 ft, with fresh straight runs.
 
The reason for the 330 ft maximum length is that each pair of conductors is
twisted with a slightly different turn rate, at about 330 ft down the line
the velocity factor is such that there is too much delay on the slower pair
and the bits start getting confused as to which frame they actually belong
to.

Jim, KR9U

-----Original Message-----
From: Kevin [mailto:rkstover@mchsi.com] 
Sent: Wednesday, June 04, 2008 8:16 AM
To: Roger (K8RI)
Cc: James Wolf; towertalk@contesting.com
Subject: Re: [TowerTalk] LMR-400 LMR-600 Equivalent (and stuff)

I have to respectfully disagree.

Cat5/5e/6 cable is made with very small diameter solid wire.
Kinking of any sort can't be good and at higher network speeds does show up.

For Roger,

Cat6 is different than Cat5/e.
Bigger conductors, tighter twist in the pairs, certified to 250Mhz and 
10Gig speeds.
Same distance restrictions apply, 100m (330ft) for a horizontal run. 
When we wired the building at my former employer we used Fiber and 
plenum rated Cat6 exclusively.

Everything you always wanted to know about Cat6

http://en.wikipedia.org/wiki/Category_6_cable

73

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