Posts tagged ‘TCXO’

Keithley 775A Programmable Counter TCXO Repair

In my last post, I did a teardown of the Keithley 775A programmable counter/timer. And while feeding a 10 MHz signal from my Rubidium frequency standard, I noticed that the measured frequency was significantly lower (9.9981 MHz) than the nominal 10 MHz reading and could not be compensated by adjusting the TCXO fine adjustment screw alone. My suspicion quickly turned to the temperature controlled crystal oscillator (TCXO). Continue reading ‘Keithley 775A Programmable Counter TCXO Repair’ »

Keithley 775A Programmable Counter Teardown

I just picked up a Keithley 775A programmable frequency counter from eBay. Specification-wise, this counter is very similar to the Racal Dana 1992 frequency counter I repaired last year. The Keithley 775A I got came with an additional channel (option 7751) and is capable of measuring frequencies up to 1.3 GHz. Continue reading ‘Keithley 775A Programmable Counter Teardown’ »

DS3232 Clock Frequency Calibration

DS3232 is an extremely accurate RTC with a guaranteed accuracy of 2.5 ppm (0 °C to 40 °C), which translates into an error of just 80 seconds over the course of a year under the worst case scenario. I had done a few projects using this chip before (you can read about them here). Continue reading ‘DS3232 Clock Frequency Calibration’ »