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Appendix D - Compatibility
150-388-125-01, Revision 01
54
September 15, 1998
HLU-388 List 2E
A
PPENDIX
D - C
OMPATIBILITY
T1 R
EPEATER
S
HELVES
AND
R
ELATED
E
QUIPMENT
The HLU-388 List 5 is compatible with the following T1 repeater shelves and associated equipment:
•
Shelf (23-inch)
–
Larus FT2 1188 (28-slot, connectorized)
–
AT&T DS1 Ext. (28-slot, connectorized)
•
Shelf (19-inch)
–
Larus FT21187 (20-slot, connectorized)
•
Cabinet Distant Terminal (23-inch)
–
Larus FT2 1190 (12 slots) for a 51A cabinet
D
OUBLER
D
EPLOYMENT
For doubler applications, one or two doublers maybe used in the HDSL loops between the HLU-388 and the HRU.
When using two doublers in an HDSL loop, the HRU must be locally powered. The HLU-388 can be used with
low-power HDU-451 List 3 and List 4 doubler units and HDU-439/437 “mini” doublers over the entire CSA range
in all three spans.
Use of the HLU-388 with the higher-powered HDU-451, List 1 or List 2 doubler is restricted per the following
deployment rules:
•
If Span 1’s loop resistance is known, then the maximum loop resistance of Span 2 is the smaller of either 800
ohms or the following calculated value:
Maximum Span 2 Loop Resistance = [2600 - 4 (Span 1 Loop Resistance)] ohms
For example, if Span 1 Loop Resistance = 550 ohms, then Span 2 Loop Resistance must be no more than 400
ohms. If Span 1 Loop Resistance = 400 ohms, then Span 2 Loop Resistance must be no more than 800 ohms.
•
If Span 2’s loop resistance is known, then the maximum loop resistance of Span 1 is calculated as follows:
Maximum Span 1 Loop Resistance = [650 - (Span 2 Loop Resistance/4)] ohms
For example, if Span 2 Loop Resistance = 700 ohms, then Span 1 Loop Resistance must be no more than 475
ohms.
•
Use only HRU-412 units with list numbers 6 or higher. Do not use Lists 1, 2, 3, 3A, 4, and 5.
•
The HRU-412 CPE current option must be set to 0 mA. Its 60 mA CPE current switch must be set to 0 mA,
or, its card edge pins must be strapped for 0 mA in the enclosure that provides these strapping options.
•
In two-doubler applications, the first doubler (the one nearest the HLU) can be a List 1 or List 2. The second
doubler, however, must be a List 3 unit.
The Span Resistance formulas in Rules 1 and 2 above illustrate that Span 1’s resistance has four
times the effect on the total circuit’s range than does Span 2’s resistance. In other words, if
Span 1 can be reduced by 50 ohms, Span 2 can be increased by 200 ohms. So, always minimize
the length of Span 1