Rigol DS1054Z: Frequecy Counter Quirk or Technical Effect?

[Darkwing]

Hi Folks!

I now own a new Rigol DS1054Z oscilloscope and I did some measurements. I measured the output of a transformer (230VAC to 12VAC) and I was expecting the 50Hz sine wave (Europe). It was there, but the frequency counter showed some weird value:



Can someone explain, why the counter is so wrong this time? With other measurements it was pretty spot on. What can be the reason? It also recongizes the 50Hz on input side correctly.


Thanks!

[ataradov]

Hardware frequency counter measures direct trigger output, which is not filtered. Enable 20 MHz bandwidth limit on the channel and the result is likely to change.

[Darkwing]

Hm, as I recall, I had that option enabled. I switched between 20M and OFF and 20M ... it didn't change a thing.

But even if it had chaged the readings of the frequency counter: the question is: what in a simple transformer could cause the 50Hz signal to go crazy like that? 

[ataradov]

Hard to tell. Try moving trigger level up and down. This is related to the way trigger system interprets this signal.

[alsetalokin4017]

Hm, as I recall, I had that option enabled. I switched between 20M and OFF and 20M ... it didn't change a thing.

But even if it had chaged the readings of the frequency counter: the question is: what in a simple transformer could cause the 50Hz signal to go crazy like that? 

Yes, in the screenshot above you have Bandwidth Limiting selected. You can tell by the "B" in the Channel 2 vertical setting box at lower left.

Try setting the Trigger Source to AC. (in the front panel Trigger section press Menu > Source > AC )

[Thomas]

Try triggering on an edge.
It looks like you have some kind of pulse triggering in the picture.