Tek 2236 Calibration

[lnx64]

Considering since buying this at an electronics surplus store, I'm surprised it at least seems like it's still in calibration.  Can anyone verify that's more familiar with scopes?  I'm still learning how to read it.  I did find that according to the frequency counter, my sound card is more accurate at a 1KHz square, than the scopes built in generator.  But not as clean.  I hope I can definitely use this scope seriously and accurately.

My Mac laptop generating 1KHz.





My scopes built in 1KHz generator.





And just for the sake of knowing what the adjustments were, here's the settings on the scope, so you see the time base and volts/div.
Channel A is on the Mac, and channel B is on the scopes built in generator.

[sync]

The probe adjust generators are usually not very accurate. Something like 1kHz +/-25%.

[lnx64]

Ouch, I would have thought if it's for calibrating the probes, it'd be a good way to calibrate the scope too..

Woops!

Ok.  So in the case of the good 1KHz square, minus the ripple, does it look like the scope is working good?  I don't know how to read the dashes on it yet..  I haven't found good scope books that cover a scope like mine, all of the papers I find are for the more modern ones.

[alm]

The probe compensation output is not a frequency reference. It's adjust the AC attenuation ratio of 10x (and 100x/1000x) probes to match the DC attenuation ratio, so the probe has a flat frequency response from DC to low frequency AC. The fundamental frequency of this signal is pretty much irrelevant, since you're adjusting the probe for the cleanest rising edge.

Frequency response of the probe compensation signal looks good. The amplitude looks like it's fairly close to 5V pp (assuming you're using a 1x probe or simple wire). Period is a little under 5 divs, with the time base set to 0.2 ms/div this is a little under 1 ms, or a frequency of a little over 1 kHz. The frequency of the signal from your sound card looks like pretty much spot-on 1 kHz (5 divs period). The high-frequency response of that sound card obviously sucks, but I guess clean square waves wasn't one of their design goals. Given the fact that the CRT of the scope was probably only specced for 2% accuracy or so, I would say that the scope appears to be fine on these time base / attenuator settings.

I would highly recommend watching Alan's (w2aew's) oscilloscope tutorial videos, or if you prefer reading the Tektronix primer XYZs of Using a Scope.

[lnx64]

Good to know it's looking on par then.

I'll definitely check that out, thanks.