Appendix B - Technical Reference
150-458-100-05
26
February 23, 2000
HRE-458 List 1, List 1B, and List 2
The physical location of the HRE-458 doubler enclosures is driven by three deployment rules:
1
The first and most important deployment rule is to place the enclosures at the electrical limits of 35 dB of
each span. This would place the:
–
First doubler at the 35 dB location
–
Second doubler at the 70 dB location
–
Third doubler at the 105 dB location
–
Fourth doubler at the 140 dB location
This allows the maximum range of 175 dB, if the fifth span to the remote unit is also 35 dB, to be realized.
2
If the first rule is not applicable and 35 dB spans cannot be implemented, the second rule is to make all the
spans the same electrical length (same 196 kHz loss). This minimizes the maximum span loss and assures the
maximum operating margin resulting in the optimum transmission performances. If specific application
constraints preclude using rule 2 or two different circuit layout choices have the same maximum span loss,
then use rule 3.
3
The third rule minimizes the power consumption and dissipation of the HLU which provides power to the
doubler. Rule 3 requires Span 1 to be a minimum and Span 3 to be a maximum. This choice minimizes the
I
2
R loss in the cable pairs and reduces the thermal stress on the HiGain Line Unit (HLU).
Refer to the HiGain ADC technical advisory number TA-015, titled HiGain Operating Ranges, for more detailed
information regarding doubler deployment rules.
Table 4.
Deployment Rules for Doublers and Remote Units
Unoccupied Slot
Numbers
Max. Number of
Occupied Slots
Thermal
Load
(a)
(a) Thermal Load: Full = maximum sunlight exposure per TR-TSY-000057. None = indoor or fully shaded.
HDU-437 and HDU 439
Max. Ambient Temp
(b)
(b) All maximum ambient temperatures of 115 °F or more with full solar load comply with the outside
deployment requirements of Section 10.2.1.3 in TA-NWT-001210. Those that do not comply are shaded.
HDU-217, HDU-219,
HDU-409, HDU-407
Max. Ambient Temp
(b)
None
10
Full
90
115
None
10
None
105
125
3 & 6 or 2 & 7
8
Full
105
125
3 & 6 or 2 & 7
8
None
115
135
2, 3, 6, & 7
6
Full
115
135
2, 3, 6, & 7
6
None
125
145
1, 2, 3, 4, 6, 7, & 8
4
Full
125
145
1, 2, 3, 4, 6, 7, & 8
4
None
135
155
Only the HDU-409 and HDU-407 doublers can be used in circuits with more than three spans.
