User's Manual

545C Operations Manual

02/10/2012 Prerelease DCN 00001789-A

• Rx 1st local oscillator phase lock loop (47.7-60.7 MHz output, 10

kHz steps limited to 53.7 – 56.7 MHz in FCC ID: BIB54505003-01)

• Rx 2nd local oscillator phase lock loop (10.6 MHz)

• PIC Microcontroller

GMSK Modulator

• DSP digital baseband GMSK generator

• I and Q DACs

• I/Q Vector Phase Modulator (GMSK)

• Pre amplifier (+13 dBm output)

All components are mounted on an 8.5" by 3.5" two-sided printed circuit

board. All components are surface mounted.

3.5 Pre-Amp, Final Power Amp, and Power Control

This board contains two low-level amplifiers that amplify the +13 dBm

(10 mW) signal from the modulator to the 2 watts required by the final

power amplifier. A special power switch is used to control the rise and

fall times of the RF power output. A duty cycle limiter circuit limits the

duty cycle of the power amplifier to 16%. A temperature sensor is also

located on this board for monitoring the internal temperature of the

MCC-545C. This temperature reading may be transmitted to the Host for

maintenance purposes.

The 100 watt power amplifier is mounted inside an aluminum enclosure

to provide RF shielding between the low level phase lock loop

synthesizers and the high power output. This board contains a T/R

switch for half-duplex operation, a harmonic low pass filter, and a dual

directional coupler for power level control. The coupler measures

forward and reverse power. If the VSWR exceeds 3.0:1 the power

amplifier automatically shuts down. The power amplifier’s parameters

are also transmitted to the Host for maintenance purposes.

A switching regulator power supply provides 5.7 volts for the processor

and transceiver boards.