ADCP-75-210 • Issue 1 • March 2007

1.9Power Amplifier Assembly

The Power Amplifier Assembly (PAA) is an electronic device that amplifies RF signals in the forward path just before they are transmitted to the RAN antenna. Up to four PAAs may be mounted in the RAN, each providing one band. Each PAA consists of a Power Amplifier (PA), a control board called the PA Interface Controller (PIC), and a cooling system. The PA is multi- channel. Different units are used for PCS, Cellular, and SMR 800 bands.

The PIC interfaces to the discrete signals of the PA. The PIC also provides DC power to the PA by converting from -48 VDC to +12 VDC or +28 VDC depending upon which PA is being used. Each PA has its own PIC. The PIC is managed is managed by the CPU over an I2C connection through its corresponding RUC. The cooling system consists of a heat sink and three fans that provide cooling for the PA by blowing external air across the heat sink. The fans are software- controlled. The PIC module monitors the tachometer outputs of the fan.

Figure 20 shows the PA assembly connection points and indicators. Table 14 describes the items called out in the figure.

8 RF IN

48V

5PWR

4 12C

 

 

1 DC_ IN

PIC LED

2

DC_ FAULT

INDICATORS

3

DC_ OUT

 

RF

21276-A

POWER 7

AMPLIFIER

6

OUT

Figure 20. Power Amplifier Assembly

Page 25