calibrating a counter

[ME]

I have ordered a GPS 10Mhz Disciplined Oscillator, its listed as having a square wave output, Will that be good for calibrating frequency counters or do i need to filter it into a sine wave?, thanks.

[Kleinstein]

A square wave should be fine for a frequency counter. It would only be in the microwave range that too much harminics could cause problems, like measureing the frequency of an harmonic.

[Solder_Junkie]

It should be fine, although some frequency counters may give erratic readings on high Voltage square waves. If you have a problem, a band pass filter will turn your square wave into a sine wave. eBay UK item 294657191023 is one example.

SJ

[benj38]

I have yet to encounter a frequency counter that will be confused by a 10MHz square wave from a GPSDO. If yours does, consider buying a lottery ticket the same day, because you are beating the odds

[tggzzz]

It should be fine, although some frequency counters may give erratic readings on high Voltage square waves. If you have a problem, a band pass filter will turn your square wave into a sine wave. eBay UK item 294657191023 is one example.

SJ

Why would anybody put a 240V signal into a frequency counter?

Hint: look under my moniker.

[edpalmer42]

Make sure that the triggering controls on the counter are set appropriately for the signal coming from the GPSDO.

Typically, the output of the GPSDO will be CMOS levels, i.e. ~5V and ~0V.  Check this on a scope.  Also make sure that the rise and fall times are nice and clean.  Then set the counter for DC triggering at a voltage of ~ 2V5.  Use 50 ohm coupling if the GPSDO allows it.

If you notice that the reading is always up and down over a tight range you might have external noise messing with the counter.  I usually use a low pass filter to remove interference from local high-power FM stations.