Motorola Bpr40 Magone Detailled 6816102h01 A Manual

Transmitter System and PLL Synthesizer2-3
3.0 Transmitter System and PLL Synthesizer
The transmitter consists of: Microphone, Pre-emphasis, Modulator, Drivers, Power Amplifier, Low-
Pass Filter, Antenna Switch and an Auto-Power Control.
3.1 TX Power Stage
The TX VCO output signal is channeled by the TX power stage via an attenuator. The attenuator is 
pie style resister attenuator, and is used for isolation between the VCO and power amplifiers. 
The TX Power stage is consist of: pre-drive (Q401), drive...

2-4Transmitter System and PLL Synthesizer
3.4 Auto-Power Control
The Auto-Power Control (APC) keeps the current constant to the final amplifier (Q403). The current 
into Q403 of the final amplifier is sensed across resistor R417. 
The voltage difference across R417 is amplified through U401 by the ratio of R423 to R417. The 
differential signal at the output of U401 is passed to Q404 and Q405 which then produce a constant 
power output to the antenna. If the current is changed due to a change of battery...

Audio and Control Circuit2-5
3.5.3 Dual VCO
The dual VCO module contains an RX VCO and a TX VCO. They are configured as Colpits 
oscillators and connected to power through cascade buffers. Only one VCO is selected at a time. 
The power source to each block is switched by transistors Q305 and Q111, and is dependent on the 
states of TX_EN1 and RX_EN. The varicap diodes CR701 and CR702 produce a change in 
frequency with a change in voltage. L703 and L706 are resonant tuning coils, which adjust the...

2-6Audio and Control Circuit
4.2 RX Sub-Audible Decode Circuit
The filter U202 is a 260Hz 8 order LPF to pass CTCSS, DCS signals and to block any other signals. 
The signals that pass the LPF filter changes this sub-tone to logic signals in the Q208 pass 
comparator (U202-D) so that the microprocessor can decode the CTCSS and DCS correctly. 
4.3 TX Audio
When the radio user pushes the PTT button, the microprocessor activates the entire transmitter 
section, including the microphone. The audio signal from...

3-1
Section 3VHF BAND 1 (136–150 MHZ) INFORMATION  

3-2RF Circuit Board and Schematic Diagram for VHF Band 1 (136–150 MHz)1.0
RF Circuit Board and Schematic Diagram for VHF Band 1 (136–150 MHz)
VHF Band 1 (136–150 MHz) Main Board Top Side 

RF Circuit Board and Schematic Diagram for VHF Band 1 (136–150 MHz)3-3
VHF Band 1 (136–150 MHz) Main Board Bottom Side 

3-4RF Circuit Board and Schematic Diagram for VHF Band 1 (136–150 MHz)VHF Band 1 (136–150 MHz) Schematic Diagram 

4-1
Section 4VHF BAND 2 (150–174 MHZ) INFORMATION (150–174 MHZ) 

4-2RF Circuit Board and Schematic Diagram for VHF Band 2 (150–174 MHz)1.0 RF Circuit Board and Schematic Diagram for VHF Band 2 (150–174 MHz)VHF Band 2 (150–174 MHz) Main Board Top Side