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Section one: General description
I、Introduction
This instrument is one of multifunctional and hi-precision frequency counters
that measures frequency from 10Hz to 1000MHz
It has function for test of frequency, period, totalize and self-checking with
8digits, 7 segment bright LED display.
It has low power consumption circuit design, small size, light weight,
high-stabilized crystal oscillator which can ensure precise measurement and
full signal input checking. This hi-precision frequency counter is the first
choices for product-line, school laboratory and radio maintenance
II、Specification
The pertinent specifications are listed as follows:
1. Measuring mode
1) Frequency measurements.
Channel A
Range: 10Hz～10MHz direct count
10MHz to 100MHz count in proportion
Direct count: 1Hz、10Hz、100Hz switch selectable.
Count in proportion:10Hz、100Hz、1000Hz switch selectable.
Gate time: 0.01s, 0.1s, 1s switch selectable.
Accuracy: ±1
±base time error ×measured frequency
count value
Channel B
Range: 100MHz～1GHz
Resolution: 100Hz、1kHz、10kHz
Gate time: 0.01s 、0.1s、1s
Accuracy: ±1 count value ±base time error × measured frequency
2) Period measurement
Input: Channel A
1
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Summary of Contents for Longwei Electric LW-1000L
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Page 1: Section One: General Description
Section one: General description I、Introduction This instrument is one of multifunctional and hi-precision frequency counters that measures frequency from 10Hz to 1000MHz It has function for test of frequency, period, totalize and self-checking with 8digits, 7 segment bright LED display. It has low power consumption circuit design, small size, light weight, high-stabilized crystal oscillator which can ensure precise measurement and full signal input checking. - Page 2 Range: 10Hz～10MHz Resolution:10 s、10 s、10 s switch selectable Accuracy: ±1count value ±base time error × measured period 3) Accumulated measurements Input: Channel A Range: 10Hz～10MHz Resolution: ±1 count pulse 4. Self-checking Display:8 LED display with 0～9 character simultaneous display 2. Input characteristics 1) Channel A Input sensitivity 10MHz range:10Hz～8MHz...
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Page 3: Section Three: Operation Instruction
Line voltage: the change of voltage of ±10% in each, the time-base frequency change ±1×10 4. General Display: 8 digits, 0.39 inch green LED display with decimal point, gate, KHz, MHz and μs indication. Power requirement: AC 220V ± 10% 50Hz Warm-up time: 20 minutes when cold started at 25℃... - Page 4 2. Features of panel features 1) Power switch: press the button to turn on. 2) Hold: press this button, the instrument will stop test and keep the data before stopping. 3) Reset: When pressed, immediately reset the counter to begin a new measurement, usually used in the totalize mode to begin a new measurement.
- Page 5 11) ATT: Input signal attenuator switch. When pressed, the input sensitivity is reduced 20 times. (Only A input) 12) A INPUT: Channel A input connector.(When the amplitude of input signal is more than 300mV, please press the “ATT” to reduce the input signal to improve to accuracy of test value).
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Page 6: Section Four: Calibration
22) Fuse: AC power protection(0.3A/220V)。 Section two: Action principle This instrument uses the principle of equal precision to measure frequency and period. That is to say, in predefined time Tx (Gate time), counter 1 counts Nx for integral pulses of measured signal while counter 2 counts No for standard pulses, and then frequency Fx and period Px of the measured signal can be determined by calculating formular easily. - Page 7 Warning Maintenance described here in is performed with power supplied to the instrument, And protective covers removed, such maintenance should be performed only by service-trained personnel who are aware of the hazard involved (For example, fire and electrical shock), Where maintenance can be performed without power applied, the power should be removed.
- Page 8 FUNCTION B.FREQ. ATT c) When observing the counter display, the reading should be 1000.000±1. If there are some errors, please adjust the frequency controlled capacitor C5 of time-base oscillator (see figure 4-1) 4. Trigger level calibration a) Set sine wave generator to 10Hz,10MHz two frequency points to calibrate, amplitude to 20mVrms.