User's Manual

TB9300 Installation and Operation Manual Installation 61

4.4.7 Tuning the Reciter

B-Band

C-Band

Before the base station is installed on site, you may need to tune the

receiver front end. The receiver front end requires tuning if the receive

frequency is shifted more than 2MHz away from the previously set

frequency, or the RSSI level of the new frequency is more than 1dB lower

than the RSSI level of the previously set frequency.

The receiver in the B-band reciter covers one of the following frequency

bands, depending on the model:

■ B2 - 136 to 156 MHz

■ B3 - 148 to 174 MHz

■ C3 - 216 to 225 MHZ

B-Band frequencies are split into 2 sub-bands:

■ B2 - 136 to 146MHz and 146 to 156 MHz

■ B3 - 148 to 159MHz and 159 to 174MHz

Each sub-band has its own helical filter (shown in

Figure 4.3 below) which

is electronically switched in or out of circuit depending on the frequency

programmed into the reciter. The bandwidth of these helical filters is

approximately ±1.5MHz.

Figure 4.3 Identifying the B-band and C-band receiver front end helical

filters

B2: 146 to 156MHz

B3: 159 to 174MHz

B2: 136 to 146 MHz

B3: 148 to 159 MHz

C3: 216 to 215 MHz