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’ »