Kenwood AG 203 Service Manual

Page 1

Trio

AG-203
CR Oscillator

Instruction Manual

Contents

Features 3
Specifications 4
Circuit Description 6
Panel Controls and Their Functions 8
Operating Instructions 10
Applications 12
Maintenance 15
Adjustment 16
Caution 17
Parts List 18
PC Board 2]
Schematic Diagram 22

Features

All solid-state circuitry ensure extreme high stability, minimum warm-up time
and less power consumption.

High reliability with adoption of direct coupled circuits throughout the entire
stage.

Compact styling with vertical type panel for easy operation.

Frequency dial scale calibrated with single-scale graduations for frequency
range lOHz to 1MHz selectable in 5 ranges.

High output design; more than 7V rms at no load and more than 3.5V rms at
6000. Output level is fully adjustable with a lOdB step, 6 range attenuator and
a level indicator.

Low output impedance of 6000. The attenuator provides accuracy of i1dB at
6000 load.

Sine and Square waves easily available.

Synchronizing input terminal.

Extremely high stability against variation of power source.

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4. Output Circuit

The output circuit converts the impedance of signal from the OUTPUT control and
feeds the signal to the output attenuator at a low impedance. It is a SEPP-OCL circuit
employing complementary transistors to provide sufficiently low output impedance
characteristics over the range from DC to 1MHz.

5. Output Attenuator

The 6-position output attenuator selects attenuations of OdB to -50dB in 10dB steps. At
the OdB position with the OUTPUT control turned fully clockwise, the output voltage
(sine wave at no-load time) is more than 7V rms.

The output impedance is rated for 6000 and the attenuation accuracy is as high as
i1.0dB at a 6000 load.

6. Power Supply
The Power supply circuit is powered by AC (100V, 120V or 220V) and delivers DC
i22V sufficiently stabilized by large capacity smoothing capacitors (2200mF x 2) and a
voltage stabilizer.

Fig. 1 Block Diagram

Panel Controls and Their Functions

The table below describes the functions of panel controls. Refer to the panel diagram
on page 9. (Fig 2)

FRONT PANEL
This lamp (light emitting diode) lights when POWER switch (2) is ON.

2. POWER
Pushbutton type switch turns on the power when pressed.

3. ATTENUATOR
6-position output attenuator selects attenuations of OdB to -50dB in lOdB steps.