Crystal PPM value test method - Database & Sql Blog Articles

Crystal Oscillator

Quartz Oscillator 3225 20M OSC

The CX-118A Crystal Oscillator Tester, developed by Shenzhen Chuangxin Instrument Co., Ltd., is a highly accurate and user-friendly device designed for testing crystal oscillators. At its core, the system uses a single-chip microcontroller to manage function switching, measurement control, and data processing.

It employs reciprocal measurement and counting technology to achieve high-precision measurements across a wide range of frequencies. The built-in stable crystal oscillator, with a stability of 5×10⁻⁷ per day, ensures that the measured data is reliable and consistent over time.

The CX-118A offers multiple measurement functions, including frequency and PPM (parts per million) testing. It is designed with user needs in mind, allowing for easy customization of features based on specific application requirements.

PPM Operation Method:

1. Press the “▲” (1) or “▼” (2) button until the “PPM” indicator lights up.
2. Press the Gate (6) button and set the “1s” light to turn on.
3. Connect the crystal oscillator to the appropriate socket and secure it. The data display window (18) will then show the actual PPM value of the tested crystal.
4. If the PPM value displays as 0000, it indicates that the nominal frequency setting is incorrect. Before proceeding with the PPM test, make sure to set the correct nominal frequency of the crystal.

PPM Setting Method:

1. Press the Parameter Key (5) once to enter the crystal center frequency mode.
2. Press the Set Button (4) once. The first digit of the display will flash, showing the center frequency of the last measured crystal. For example, if the last crystal was 32.768KHz, this value will be displayed.
3. Enter the standard frequency of the crystal you are testing.
4. Press the Set Button (4) again. A digit in the display will start flashing. Use the “▲” or “▼” buttons to adjust the value accordingly.
5. Once the desired frequency is set, press the Set Button (4) to save the value. The display will now show the nominal frequency of the current crystal being tested.
6. Finally, press the Parameter Key (5) once to automatically switch to the frequency test function.

Tip:

After saving the PPM settings, press the Parameter Key (5) to view the center frequency of the last setting. If the device does not respond correctly, press the Set Button (4) once and follow the steps above to reset.

Important Notes and Maintenance:

This instrument uses large-scale integrated circuits, so it is recommended to avoid using a two-core soldering iron during repairs. When calibrating or performing tests, ensure that the outer casing of the device or any connected equipment is properly grounded to prevent accidental damage.

Never operate the device while replacing the fuse. Always disconnect the power cord from the AC mains before performing any maintenance to ensure personal safety.