Ref: 11640062
Title: Cabling Basics:  Ethernet Coaxial Cable Specs
Date: 2/21/90

Copyright 3Com Corporation, 1991.  All rights reserved.

REFERENCE  CONDUCTOR  DIELECTRIC  SHIELD  EXTERNAL     Zo   Vp     C
  TYPE        SIZE     DIAMETER    TYPE    JACKET     Ohms   %     nF
-----------------------------------------------------------------------
RG 58 C/U    Cu Sn        PE      Cu Sn   Black PVC    50   66%  97nF/Km
           AWG 20(19)    2,95      95 %     4,95      +/-2
-----------------------------------------------------------------------
ETHERNET     Cu Sn        PES     Cu Sn   Yellow PVC   50   81%  85nF/Km
 YELLOW     AWG 12       6,27      93 %     10,2      +/-2
            0 2,17             Al/P/Al 100%


The overall specifications above were taken from IED specs and
Recommendations MIL C / IAN 17.  Ethernet IEEE 802.3 Specifications
indicate use of the two kinds of a.m. cables.

The 3Com LanScanner setup for .66% solid prop. delay refers to RG 58 C/U
cable.  The 3Com LanScanner setup for .68% foam PVC prop. delay refers to
similar cables but with PVC foam multicellular dielectric, such as Digital
Thin Wire.

Do not use RG 58 A/U or RG 58 U cables with 3Com transceivers, because
they have inferior characteristics to RG 58 C/U.  Differences include a
smaller copper braid, a smaller PVC jacket, and inner conductor and
shielding braid usually made of red copper.  As a rule of thumb, the heavier
the coax cable, the greater the quality.


