FUNCTION GENERATOR OPERATION MANUAL

Transcription

1 FUNCTION GENERATOR OPERATION MANUAL INDEX 1. Introduction (3) 2. Specifications (3) 3. Working Theory (7) 4. Structure (8) 5. Operation & Maintenance (9) 6. Accessories (14) 1

2 This instrument is a highly stable, multipurpose, broad bandwidth function generator, which can directly generate Sine, Triangle, Square, Ramp, Pulse waveforms as well as Linear & Logarithm Sweep signals. Application of Single-chip-machine intelligently controls all of the functions, displays and indicators, which allow users to know about the working status of the instrument easily and accurately. 1. Specifications 1.1 Frequency Range: 0.6Hz-6MHz 1.2 Waveform: Sine, Triangle, Square, Positive & Negative Ramp, Positive & Negative Pulse. Symmetry of Ramp and Pulse is variable within 80:20 (1Hz~100kHz) 1.3 Sine Waveform: 1) Distortion: 1% (0.1Hz~100kHz) 2) Frequency Response: ±0.5dB(0.1Hz~100KHz); ±1dB(3MHz); ±2dB(6MHz); 1.4 Rising/Falling Edge of Square Waveform: 50ns 2

3 1.5 TTL Output: 1) Higher Level 2.4V, Lower Level 0.4V, capable of driving 20 TTL loads. 2) Rising time: 30ns 1.6 Output: 1) Impedance: 50Ω±10% 2) Output Amplitude: 20Vp-p (open circuit), 3) Output Attenuator: 20dB, 40dB, 60dB 4) DC Offset: 0 ~±10V adjustable 5) Display Error of Amplitude: ±10% ±2 digits (output level higher that 1/10 of full scale) 1.7 Power Output: 1) Amplitude: 20p-p 2) Output power: Max. 5W 1.8 VCF Input: 1) Max. Voltage: -5V~0V ±10% 2) Max. Control rate: 1000:1 3) Frequency: DC~1kHz 1.9 Amplitude Modulation: 1) Carrier Bandwidth: 2) Modulation Freq.: 400Hz (INT), 0~1MHz (EXT) 3) Modulation Depth: 0~85% 3

4 1.10 Frequency Modulation: 1) Deviation: 0 ~ 10% 2) Modulation Freq.: 400Hz(INT), 0 ~ 20kHz (EXT) 3) Distortion: 1.5% ( fc=500khz, fm=1khz, 10%) 1.11 Sweep 1) Sweep mode: Linear, Logarithmic. 2) Sweep time: 10ms~5s 3) Sweep rate: 1000:1 4) Output Amplitude: 7Vp-p 5) Output Impedance: 600Ω 1.12 Frequency Counter: 1) Measuring Range: 1Hz-20MHz 2) Input Impedance: 1MΩ / 20pF 3) Sensitivity: 10mVrms 4) Max Input: 150V AC+DC (with attenuator) 5) Input attenuator: 20dB 6) Measuring Error: not more than ±1 digit 1.13 Power Supply 1) Voltage: AC 220V ± 10% 2) Frequency: 50Hz±2Hz 4

5 1.14 Operating Ambient: 1) Temperature: 0 C~40 C 2) Humidity: RH 90% 3) Atmospheric Pressure: 86kPa~104kPa 1.15 Dimension (mm): 290L 260W 90H 1.16 Weight: 3kg 2. Working Theory Figure Waveform Generator Circuit This segment is consisted of MAX038 Function Generator, Frequency & Duty Rate control circuits. Waveforms are selected by SCM. 5

6 2.2 SCM (Single-chip-machine) Circuit This segment is consisted of SCM 89C52, Panel Input, Frequency & Amplitude Display and Output & Indicator circuits. The main jobs are: Control waveform of output signal; Test and display the frequency of output or external input signal; Display amplitude of output waveform. 2.3 Frequency Counting Circuit: It is consisted of Broad-banded Amplifier and Square-waveform Regulator, which external signal will go through. 2.4 Power Amplifier In order to insure the stability and high slew rate, dual channel power amplifier is employed. The entire amplifier is with the characteristic of phase inversion. 2.5 FM Mode When SWP/FM switch being pressed down and MOD switch is pulled up, a 1KHz modulation signal which generated by RC oscillator is applied to VCF end. 2.6 Power Supply Four sets of power supply, ±23V/±15V/±5V/+5 are employed. ±23V is used for Amplifier. ±15V and ±5V are used for Waveform Generator. +5V is mainly for SCM circuit. 6

7 3. Structure This instrument has an all-metal frame and cover, plastic front panel with a elegant and small-sized appearance. Most of the components (including switches and knobs) are fixed on two PCBs. All adjustable components are located at an easy-to-adjust position. Only to unscrew the back panel and remove the cover up and down when the instrument need to be adjusted or repaired. 4. Operation and Maintenance 4.1 Symbols and functions in front panel and rear panel: See Table 1, Figure 2 and Figure 3. Figure 2 7

8 Table 1 NO SYMBOL DESCRIPTION OPERATION 1 POWER Power Switch Push down, power on 2 3 Frequency Range Selection Frequency Range Selection Press the key, the multiples of freq. will be changed from low to high. Collaborate with Knob 19 to set output frequency. Press the key, the multiples of freq. will be changed from high to low. Collaborate with Knob 19 to set output frequency. Press the key to change output waveform. Work 4 Waveform Selection with knob 17 and key 18, polarity of ramp and pulse can be selected. 5 DC OFFSET DC Offset 6 DC Offset Knob Linear/Logarithmic Press button. Indicator lights when the function is activated. DC output can be adjusted with from -10V~+10V(Output waveform is 5Vp-p) Sweep mode will change in sequence each time the 7 MODE /External Sweep selection button is pressed. 8 SPEED Sweep Speed Adjust the knob to change sweep speed. 9 Output Attenuator 10 OUTPUT Voltage Output Press the button to set attenuation among 0, 20dB, 40dB and 60dB. Indicators light respectively. Output terminal of waveforms, max. output 20Vp-p with impedance of 50Ω. Activate modulation mode with button 24. If the knob is Pull-out position, the instrument is in AM 11 AM/FM AM/FM Adjustment mode, modulation depth can b adjusted with the knob. If the knob is Push-in position, the instrument is FM mode, frequency deviation can be adjusted with the knob. 8

9 12 AMPLITUDE 13 INPUT Output Amplitude Adjustment Waveform Inversion Counter Input Terminal Work with button 9 to adjust amplitude of output waveforms. To test the frequency of an external signal, connect the signal to this terminal. When external signal is selected and the signal is too 14 EXT ATT20dB LPF Selector of INT/EXT signal, 20dB Attenuator and Low-Pass Filter strong, press the key, 20dB attenuator is activated with the indicator lit. Press the key again, LPF indicator lights(with attenuator, cutoff freq. 100kHz) About 20 seconds after no signal is detected, 0 will be displayed. 15 WIDTH Sweep Width Use the knob to adjust sweep width when the instrument is in sweep mode. Display peak to peak value of output signal (open circuit). If a 50Ω load is connected, actual value on the load is 1/2 of that is displayed. If desired output 16 Amplitude Display amplitude is lower than 1/10 of max. value when amplitude knob is fully turned, connecting an extra attenuator is advised. If the instrument is working in AM mode, displayed amplitude is an Un-cal value. 17 SYMMETRY Symmetry Adjusting Symmetry can be adjusted from 20:80 to 80: Symmetry Activating Key Frequency Adjustment Press the key to activate symmetry adjusting knob. Turn the knob CW, output frequency is increased and vice versa. Display the frequency of output signal or external input signal. Indicator GATE blinks when counter 20 Frequency Display is working well. If input frequency over 20MHz, indicator OV.FL will be on. Hz and khz indicate what units of frequency would be at the moment when one of them turns on. 9

10 4.2 Symbols and functions in rear panel: Figure 3 21 Power Socket AC 220V/0.5A fuse or AC110V/1A fuse. 22 Line Voltage Selection 110V/220V switching. a) Input terminal of Voltage-Control-Frequency, input voltage range 0~-5V. 23 VCF IN/EXT MOD IN/EXT SWP IN Terminal b) Input terminal of External Modulation signal. c) Input terminal of External Sweep signal. A sweep signal is generated while frequency vary along input control signal. 24 MOD 25 TTL OUT ON/OFF switch of AM/FM, INT/EXT modulation selection. Output terminal of TTL pulse, with impedance of 50Ω. 10

11 4.3 Service and Calibration This instrument can be operated continuously in proper ambient, but you are advised to calibrate it every three months. Calibration procedure is as: 1) Sine Distortion Calibrating: Turn Amplitude Adjusting Knob to its max, select sine waveform output and set frequency at 1kHz. Connect this signal to a distortion meter. Adjust RP102 to have distortion match technical requirement. 2) Output Amplitude Calibrating: Set the instrument in the same working status as 1), connect the signal to an oscilloscope. With observing peak-peak value of the output signal, adjust RP601 to have the output amplitude match technical requirement. 3) Frequency Calibrating: Set frequency counter at EXT, connect a 10MHz signal of standard oscillator to the input terminal. Adjust C607 to get standard kHz on the LED display. Set the amplitude of the standard signal to 100mVrms, adjust RP401 to have kHz stably displayed on LED. 11

12 4.4 Trouble Shooting Sufficient knowledge is needed when you are going to fix problems on this instrument. Locate the problem area in PCB by with observing the phenomenon, visual inspection is suggested in first place, and then check the PCB in static and dynamic mode. Replace the component which is found broken. 5. Accessories Operation Manual Power Cord Test Lead(50Ω) BNC Cord Fuse (0.3A) 1copy 1pc 1pc 1pc 2pcs 12