Hi Franc,

There are some ways to get the stable frequency:

1) You may use the GPS-receiver output (GG-24 or ACUTIME II for example) which gives second labels with the accuracy 0.001 ppm or better!

2) You may use any industrial frequency counter with 10 MHz reference frequency as a rule.

3) You may count your own reference frequency source between the twenty-four hours labels transmitted by all of the LW-, MW- or FM-stations.

I wonder, if you don’t object, what are the electrical features of your frequency counter? Some years ago I built a frequency counter based on i80C85 too. It had six true digits to display the frequency anywhere from 1 Hz to 100 MHz. The measurement period was about 1 second. Besides it had the minimal number of the integrated microcircuits.

Bye,

Igor