Power Supply Circuit - Alinco DR-135 Service Manual

5. DTMF Encoder
6. Tone Encoder
7. DCS Encoder
8. CTCSS, DCS Decoder

8) Power Supply Circuit

When power supply is ON, there is a "L" signal being inputted to pin 39 (PSW) of CPU which enables
the CPU to work.
Then, "H" signal is outputted from pin 41 (C5C) of CPU and drives ON the power supply switch
control Q8 and Q7 which turns the 5VS ON.
5VS turns ON the PLL IC (IC116), main power supply switch Q127 and Q122, AF POWER IC117
and the 8V of AVR (IC115).
During reception, pin 29 (R5) of CPU outputs "H" level, Q124 is ON, and the reception circuits
supplied by 8 V. While during transmission, pin 28 (T5) of CPU outputs "L" level which is reverse by
Q11 so that the output in Q128 will be "H" level, Q123 is ON, and the transmission circuit is supplied
by 8 V.
Or, in the case when the condition of PLL is UNLOCK, "H" level is outputted from pin 14 of PLL IC,
UNLOCK switch Q129 is ON, transmission switch Q128 is OFF which makes the transmission to
stop.
1. ACC External Power Supply Terminal
10
The CPU (IC1) is equipped with an internal DTMF encoder. The DTMF signal
is output from pin 10, through R35, R34 and R261 (for level adjustment), and
then through the microphone amplifier (IC114:A), and is sent to the variable
capacitor of the VCO for modulation. At the same time, the monitoring tone
passes through the AF circuit and is output from the speaker.
The CPU (IC1) is equipped with an internal tone encoder. The tone signal
(67.0 to 250.3 Hz) is output from pin 9 of CPU to the variable capacitor (D122
and D123) of the VCO for modulation.
The CPU (IC1) is equipped with an internal DCS code encoder. The code
(023 to 754) is output from pin 9 of CPU to the variable capacitor (D124) of
the PLL reference oscillator. When DCS is ON, DCS MUTE circuit (Q126-
ON, Q133-ON, Q132-OFF) works. The modulation activates in X102 side
only.
The voice band of the AF output signal from pin 1 of IC104:A is cut by sharp
active filter IC104:B and C (VCVS) and amplified, then led to pin 4 of CPU.
The input signal is compared with the programmed tone frequency code in
the CPU. The squelch will open when they match. During DCS, Q108 is ON,
C156 is working and cut off frequency is lowered.
When optional power supply cord EDC-37 etc. is connected to the external
power supply terminal JK101, with ACC power supply ON, switch Q101 will
turn ON, 5 V of AVR IC101 pin 2 (STB) becomes "L" which makes C5V to turn
ON. With this, it can turn the power supply of the radio ON.