0049-1800-xxx 326X V.34, V.34-SDC and V.32bis Series Modem – USER’S GUIDE 02/23/2010
Rev. A
Page 150
of
205
For example, assume you require a 30-foot cable. You intend to operate your modem at 64.0
kbps. After looking at Table B-4, you determine that the maximum capacitance for the cable is
900 pF. According to the formula above, divide 900 pF by 300 feet. The result is 30 pF per
foot:
Raymar-Telenetics recommends you use Raymar-Telenetics cables to attach your 326X modem(s) to
DTE(s). Use Table B-5 to select cable(s) for your application.
To use non-Raymar-Telenetics cables, Table B-6 provides examples of vendor cable wire length
versus DTE rates for 326X stand-alone units.
NOTE
: The part numbers specified in Table B-6
are
not
for complete cables, but for the wires that are available with the correct capacitance to support the
higher rates of the 326X Modem.
Table B-5.
Raymar-Telenetics DB-25 Low Capacitance Cables for 326X
Description
Raymar-
Telenetics
Product
Code
Up to 19.2
kbps (ft)
Up to
64.0 kbps
(ft)
Up to
96.0
kbps (ft)
Up to
115.2
kbps (ft)
Raymar-Telenetics
Male 25-Male 25
Straight-through
92153
92152
92151
92150
50 30 10 6
Raymar-Telenetics
Male 25-Female 25
Straight-through
92157
92156
92155
92154
50 30 10 6
Raymar-Telenetics
Male 25-Feale 25
Crossover
92161
92160
92159
92158
50 30 10 6
NOTE:
Raymar-Telenetics DB-25 Cables have a conductor capacitance of 11 pF/ft and a shield capacitance of 20 pF/ft
for a total capacitance of 31 pF/ft. For example, operating at 19.2 kbps, a 50-ft length of cable multiplied by a total
capacitance of 31 pF/ft yields a maximum allowable cable capacitance of 1550 pF, which is acceptable in accordance with
Table B-4.
