KL-900B Analog Communication System for the walky-talky based (144MHz VHF)

KL-900B Analog Communication System discloses the secret of the walky-talky based
on the 144MHz VHF band. It breaks the circuit of walky-talky into 4 blocks : receiver block, 
transmitter block, audio amplifier block and microphone amplifier block.

Block diagrams are printed clearly on the panel of the module, giving students a comprehensive view of how walky-talky works.

1.  Introduction to Analog Communication System 
     (1) Resetting the transceiver
     (2) Setting the channel frequency
     (3) Expanding frequency range 
     (4) Operating two keys
     (5) Operating SET key

2.  Microphone Amplifiers
     (1) Measuring PTT DET output
     (2) Measuring transmitted signal
     (3) Measuring MIC-AMP (LIM) output
     (4) Measuring MIC-LPF output

3.  Phase-Locked Loops
     (1) Measuring crystal oscillator output
     (2) Measuring data, clock and LE in receiving
     (3) Measuring data, clock and LE in transmitting
     (4) Measuring phase comparator inputs
     (5) Measuring phase comparator output

4.  Voltage-Controlled Oscillators
     (1) Measuring RX VCO characteristic 
     (2) Measuring TX VCO characteristic

5.  RF Power Amplifiers
     (1) Measuring TX POWER AMP input and output
     (2) Measuring APC AMP input and output

6.  RF Amplifiers
     (1) Measuring RF AMP input
     (2) Measuring RF AMP output
     (3) Measuring BPF output

7.  Mixers and IF Amplifiers
     (1) Measuring RX VCO output
     (2) Measuring 1st MIXER output
     (3) Measuring CRYSTAL BPF output
     (4) Measuring 1st IF AMP output
     (5) Measuring 1st IF AMP input and output

8.  FM Demodulators
     (1) Measuring second mixer output
     (2) Measuring 2nd FILTER output
     (3) Measuring S-MET AMP output
     (4) Demonstrating squelch control

9.  Audio Amplifiers
     (1) Measuring AF PREAMP input
     (2) Measuring AF PREAMP output
     (3) Measuring AF POWER AMP output