I recently bought an HP 5316A frequency counter. It has the ability to use an "external reference". Does that mean it ignores its internal clock and uses the external signal in lieu of the clock?

Is it complicated to provide the external reference signal? What is involved?


1 Answer 1


Yes, the counter will use external clock as its time base. The instrument itself has an internal reference clock, but it has certain limited accuracy. If someone has a better quality "atomic clock" (as rubidium standard or else), one can use it to improve the counter parameters significantly.

What is involved? An external clock generator and BNC coaxial cable.

  • \$\begingroup\$ Does the frequency have to match? The 5316A documentation seems to suggest that it expects the external signal to be 1, 5 or 10 MHz. I suppose that means I can't use a 16.9344Mhz clock generator. \$\endgroup\$ Oct 16, 2016 at 18:59
  • \$\begingroup\$ You probably can, but then you will need to multiply every instruments readings by a factor of 1.693440000. Do you have a cesium clock standard with 16.9344 MHz output? \$\endgroup\$ Oct 16, 2016 at 19:19

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