**Part Number:**SN74HCU04

Hi,

I use the SN74hcu04 in a basic 60khz tuning fork oscillator circuit. I have sold this product for decades without issue. Suddenly, this past year, I have encountered over 25% of production where the oscillator is unstable. Through substitution, I have determined that it is the device that is at fault. Increasing the circuit input capacitor from 22pF to 27 pF restores oscillator stability. Has the Mfg process changed in some way that would change the device input capacitance or gain?

I am about to run a new production order, and need to have some confidence that changing the capacitor to 27pF is going to solve this problem.

the circuit runs on a regulated 5V line powered by a 9V battery.

thanks for any help or guidance you can offer.

Kevin

KAB Electro-Acoustics

Website http://www.kabusa.com

Phone (908) 754-1479

Fax (908) 222-3442