Sailor COMPACT HF SSB T2130, Technical Manual

Page: 113 / 138

5 CIRCUIT DESCRIPTION AND SCHEMATIC DIAGRAMS T2130
TUNE MOTOR CONTROL
The main functions of this circuit are to control the motor MO1 in the AT2110 at two speeds, high and low,
and detect when the variable capacitor has rotated one half turn.
The speed of the motor is selected from the microprocessor via the serial device bus and the shift register
U14 (74HC595).
Two identical circuits are connected to two outputs of U14.
QA, pin 15 controls the low speed as the D07 zener diode is a 9.1 Volt type.
QB, pin 1 controls the high speed as the D08 zener diode is an 18 Volt type.
The selected zener voltage is buffered by the output transistors Q05 and Q06.
When the motor is running as it does when the power is turned on (high speed) or when tuning the AT2110
(high or low speed), a current flows in the emitting light diode in the optocoupler OC01 on the Main Board
(1) in the AT2110. R05 and U10/2 on the Connection and Interface Board (2) and R25 on the Main Board
(1) in the AT2110 ensure this. The detector in the optocoupler OC01 and Q01 on the Main Board (1) are
both in saturation state caused by the light from the LED in the OC01.
The transistor Q07 on the TX-processor (3) is on (controlled by the microprocessor). This ensures a
current flow in R41 on the TX-processor (3) and in Q01 (and the detector in OC01) on the Main Board
(1) in the AT2110.
The collector of the Q01 on the main board in the AT2110 is sensed by the divider R40 and R39 and the
Schmitt Trigger U04/4 (74HC132) which is connected to the microprocessor, port 5, bit 7, (U02, pin 24).
The light is broken in the open type optocoupler OC01 on the Main Board (1) when the variable capacitor
C01 in AT2110 has maximum capacity and when it has minimum capacity (every 180°).
When the light is broken in the optocoupler OC01, the current flow stops in the detector in OC01 and Q01
on the Main Board (1) in AT2110. This gives a level shift which is detected by Schmitt Trigger U04/4 and
the microprocessor is informed. The microprocessor turns off the supply voltage to the motor MO1 and
the rotation stops.
When the motor MO1 must run at low speed (the AT2110 is tuning) it is always started at high speed and
reduced to low speed when the rotation has begun. The high speed time period is the time it takes to rotate
the variable capacitor C01 so far that the light from the light emitter diode in OC01 turns on the detector
in OC01 and the transistor Q01 on the Main Board (1). This is detected and the microprocessor will
immediately change to low speed.
PAGE 5-17
9315