Daniels P25 - SUBRACK

UG-001 Daniels P25 Radio Systems
www.danelec.com
Chapter 6: Radio System Components
36
User
Guide
SUBRACK
The SR-39-1 subrack is designed to hold and interconnect the MT-4 series of P25 receiver, transmitter
and control modules on one universal motherboard. The subrack has room for two transmitter and
receiver pairs. The left side connectors are reserved for transmitter A and receiver A, while the right
side connectors are reserved for transmitter B and receiver B. See Figure 6-1.
Figure 6-1: Standard Subrack Confi guration
If a VHF or UHF 30 Watt power amplifi er is installed, only one transmitter and receiver pair can be
installed. The power amplifi er takes up two slots as shown in Figure 6-2.
Figure 6-2: Standard Subrack with Power Amplifi er
Power Input
The main power input (+10 to +17 Vdc; +13.8 Vdc nominal) connector is located on the back of the
subrack, on the motherboard. There is an identical +9.5 Vdc power output connector on the motherboard
that is used to power other Daniels equipment at +9.5 Vdc (the CI-RC-4M controller for example). Do
not connect the main power input to the +9.5 Vdc power output connector, as a transient suppressor
(over voltage protection) will short to ground to protect the equipment.
Reverse voltage protection and over voltage protection (transient suppressor) is provided at the main
power input as well as the +9.5 Vdc line. The main power input is protected with a standard fast-blow
15 amp fuse. These components may require replacing if the power supply is not connected properly,
or even after a power surge or a lightning strike. The two transient suppressors have different voltage
ratings for the main power input and +9.5 Vdc lines. Figure 6-3 shows the subrack / motherboard rear
view.
SYSTEM
MONITOR
RECEIVER
B
TRANSMITTER
B
RECEIVER
A
TRANSMITTER
A
CONTROL
CARD
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POWER AMPLIFIER
A
SYSTEM
MONITOR
RECEIVER
A
TRANSMITTER
A
CONTROL
CARD
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