How to calibrate probes for Advance Instruments Oscilloscope OS 1000?

[wa7son]

Thanks to a fellow EEVBlog user, I have an Advance Instruments OS 1000 oscilloscope. I bought two passive probes as it didn't come with any, and have since learned that I better calibrate the probes against a square wave signal generated by the scope.

Question 1:

The OS 1000 scope have two calibration sockets labeled "CAL 1V" and "GATE 10V" respectively. My first gut feeling told me to use the "CAL 1V" socket, but from reading the manual it seems "GATE 10V" is more appropriate as it's synced to the horizontal sweep (see attached picture from the manual of the OS 1000A model, which I think is similar enough to be used for this). Any ideas?

Question 2:

Normally I would expect two separate points on where I could hook the probe tip and ground clip respectively. But I'm not sure how to use any of these sockets. They look like the female end of a small banana plug - but I'm not sure (see attached picture, bottom right). Anybody knows?

[Simon]

The test output does not need a ground as the test output and oscilloscope input have the same internal ground. Sounds like you should calibrate at 10V. Make sure you use a non conductive screwdriver/twiddler to make adjustments.

[wa7son]

Thanks Simon

Have you ever seen these type of calibration sockets before? I wonder how I would connect the tip of the probe to it...

[Simon]

one is called cal and the other gate, surely you use the 1V "cal". Those look like 4mm sockets so try a banana plug and clip your probe to it.

[wa7son]

Thanks again

I don't have any lying around, but I'll head to the store tomorrow to buy one and try it out

[nrxnrx]

Multimeter probes have a 4mm banana plug at the non-pointy end..

[Simon]

Yes but that is a long wire to put a test signal through that needs calibrating for the rise edge overshoot

[nrxnrx]

That makes sense to me (all that added inductance), but I've just tried it.

This is with a ~60cm lead + probe :


..and this is with the probe attached directly to the cal post:

[barry14]

You should use the 1v cal signal to check your probes as that is what it was designed for. The 1v level should be accurate to a few percent. The 10v gate signal is a signal that is high (about 10v) during the horizontal sweep and low otherwise. It is not intended as a calibration signal but for use in syncing the oscilloscope sweep to other equipment. You can certainly look at it once your probes have een adjusted using the cal signal.

[Simon]

That makes sense to me (all that added inductance), but I've just tried it.

This is with a ~60cm lead + probe :


..and this is with the probe attached directly to the cal post:

and there is a slope there, a delay in rise and fall caused perhaps by that inductance. Were there some overshoot that needed calibrating it may get hidden. It's one thing to use a known system and see what you expect, but it's another to be running blind with an unknown system.

[tautech]

You should use the 1v cal signal to check your probes as that is what it was designed for. The 1v level should be accurate to a few percent. The 10v gate signal is a signal that is high (about 10v) during the horizontal sweep and low otherwise. It is not intended as a calibration signal but for use in syncing the oscilloscope sweep to other equipment. You can certainly look at it once your probes have been adjusted using the cal signal.

Exactly this ^. 

[wa7son]

I don't have any lying around, but I'll head to the store tomorrow to buy one and try it out

Bought a 4mm banana plug and used the CAL 1V port. It worked like a charm for getting the probes calibrated. Thanks for all the help