Combination of Twisted Pair and Coax
Networks
A Two-Port Link is used to combine twisted pair
network and a coax network. A Two-Port Link has
a coax connector on one side and two modular
jacks on the other and contains the proper
impedance-matching circuitry. Refer to Figure 3
for an illustration of a twisted pair network
combined with a coaxial network.
Proper Connection for Twisted Pair
Each twisted pair compatible ARCNET node
would typically have
two RJ-11 modular
connectors mounted on the node card (refer to
Figure 4). PHASE A should be connected to pin 2
of the connectors and PHASE B to pin 3. A
twisted pair segment would have an RJ-11
modular jack on each end (see Figure 5). Please
note that the suggested numbering scheme of the
modular jack shown in Figure 5 may not be
consistent with that found on some manufacturers'
products. Please ensure consistent connection of
Phase A and Phase B signals throughout the
network to avoid the reception of erroneous data.
PARAMETER
Wiring
Number of Twists/Foot
DC Resistance
Characteristic Impedance
Maximum Attenuation
Table 1 - Specifications for Cabling
VALUE FOR COAX
VALUE FOR TWISTED PAIR
RG62
N/A
3.4 Ohms/1000 ft.
93 Ohms at 1 MHz
5.5 dB/1000 ft. at 5 MHz
Solid Copper 22, 24, or 26 AWG
2 min.
28.6 Ohms/1000 ft. max.
105 Ohms
20% at 1 MHz
16.0 dB/1000 ft. at 5 MHz
6
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