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Shielded Twisted Pair (STP)
Page B-4
IBM Type 6 consists of two STP of 26 AWG stranded wire for data.
Because of its high attenuation, Type 6 is used only in patch panels or to
connect devices to/from wall jacks. Attenuation for Type 6 cable is 3/2 x
Type 1 cable (attenuation for 66 m of Type 6 = attenuation for 100 m of
Type 1).
IBM Type 9 is similar to Type 1, but uses 26 AWG solid wire. Like Type 6,
because of its high attenuation, Type 9 is used only in patch panels or to
connect devices to/from wall jacks. Attenuation for Type 9 cable is 3/2 x
Type 1 cable (66 m of Type 9 = 100 m of Type 1).
IBM Types 6 & 9 are to be used only for lobe connections
from station to wall jack and patch panels.
B.2.2 STP Lobe Lengths
The maximum lobe length attainable under ideal conditions, is shown in
Table B-4. Cable routing, connector attenuation, noise and crosstalk can
adversely affect the maximum lobe length.
B.2.3 Mixed STP Cable Types
If cable types are to be mixed in the LAN, compensations must be made
for the different cable attenuations. For example, Type 6 & 9 cables can be
run for only 2/3 the distance of Type 1: 100 meters of Type 1 ≈ 66 meters
of Types 6 or 9)
Table B-3. STP Cable Type Specifications.
IBM
Type
Operational
Frequency
Impedance
Attenuation per...
1000 m (1000 ft)
1 & 2 4 MHz ≤ 150Ω ±15% ≤ 22 dB (≤ 6.7 dB)
16 MHz ≤ 150Ω ±15% ≤ 45 dB (≤ 13.7 dB)
6 & 9 4 MHz ≤ 150Ω ±15% ≤ 33 dB (≤ 10.0 dB)
16 MHz ≤ 150Ω ±15% ≤ 66 dB (≤ 20.0 dB)
NOTE