OSC5A2B02-based 10 MHz Oscillator
May 6th, 2024, last changes on June 14th, 2024A 16.69 euros 10 MHz heated reference generator? Yes, here:
Some components on the PCB are dirty, the case of the oscillator looks like it had hard time travelling from China to Europe, but well... let give it a try.
It accepts voltage between 7 and 13V DC, consists of a downstep voltage regulator to 5V, offers two outputs: sine and TTL-level signal, and a potentiometer for fine adjustment of the frequency. It is based on the OSC5A2B02 quartz module.
At 7.5V input:
- It starts with ca. 0,46A current.
- The current slowly grows to ca. 0,54A within the next minute.
- After further 11 seconds (1 min. 11 seconds in total) the current drops down to 0,32A.
- The current slowly drops down to ca. 0,23A within the next two minutes.
The metal cover of the quartz module reaches something above 40°C.
First measurements
TTL output: 1.2V low (TTL output expected to provide 0..0.4V) which is definitely too high, 3.88V high at Hi-Z load (TTL output expected to provide 2.7..5V) which is fine.
Frequency stability
Using a counter of a Siglent SDG 2122X generator, the results over 1000 cycles (corresponding to duration of 1000 seconds measurement) of the sinus output look as follows:
| Frequency | Pulse width | Duty | Frequency deviation | |
|---|---|---|---|---|
| Mean | 9.999 997 4 MHz | 50.7 ns | 50.7% | -0.256 ppm |
| Min | 9.999 997 3 MHz | 50.7 ns | 50.7% | -0.274 ppm |
| Max | 9.999 997 7 MHz | 50.7 ns | 50.7% | -0.233 ppm |
| Sdev | 98.792 607 mHz | - | - | 0.010 ppm |
Not bad!
Rotating up to two rotations of the calibration resistor (left and right from the delivered position) did not have any measurable influence on the generated frequency.
The measurement has been performed after over 30 minutes of heating up both, the counter and the tested oscillator.