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csbluesman 22nd April 2013 01:31 AM

Help with oscilloscope probes.
Hello, I'm new to this forum. I'm setting up my own little home electronics lab. Today I purchased a used Hp Agilent 54601a oscilloscope on eBay. It doesn't come with any passive probes. So I'm want to own if anyone has had luck with the after market style probes selling on eBay or do I have to pay extra for the HP probes? I plan on using the scope for repairing and building music equipment. I'm trying to keep my cost to a minimum so I'm hoping for some sound advise. Thanks, Clint. :)

bear 22nd April 2013 02:42 AM

Standard 50mhz or 100mhz "aftermarket" probes will work ok.

IF your scope has range switching based on the BNC end of the probe making contact with an outer ring (Tektronix did this) then it will not show the proper range if you turn on the 10x switch.

Btw, a 10x probe or a 10X switch on a probe is a very good idea.

If you look at the max Vertical amp voltage range, you'll see that you probably must have a 10x multiplication for tube work... even if you have enough range on the vertical amp, the 10x probe is still good.

I didn't look to see what the max bandwidth for you scope is, but for most audio work, the fastest probe is not a big concern.

csbluesman 22nd April 2013 04:12 AM

Thanks. I believe it has a bandwidth of 100MHz. I went ahead and ordered a couple of no name probes that are switchable between 1x & 10x from a Chinese supplier. I may need to order another set too but I'm hoping they will get me going for a little bit.

bear 22nd April 2013 12:16 PM

I think you will be fine... there is a compensation in the body of some probes and inside the scope on some scopes to make the square wave from the calibrator look just right... check the calibrator square wave and see...

You also need a ground clip lead too! :D

bear 22nd April 2013 02:50 PM

should have written "compensation adjustment" - usually a little screwdriver adjustment on the body of the probe... if it exists.

csbluesman 23rd April 2013 12:12 AM

Sounds good. I will let you know if it doesn't work out.

DUG 23rd April 2013 02:38 AM

Be aware that probes are designed to compensate a certain range of scope input capacitance.

If your scope is not within this range then you may not be able to compensate the probe properly.

This will show up on square waves with rounding or overshoot and in sine waves with high frequency roll-off or peaking.

Just so you know.


csbluesman 23rd April 2013 02:48 AM

Dug, are you saying this may be a problem even if the probes are advertised to be in the same range as the scope.

bear 24th April 2013 12:27 AM

Just put them on the calibrator output and look at the waveform, the squarewaves should be flat without leading edge overshoot or undershoot. All the probes I have gotten work fine with Tek scopes, Phillips scopes and other random scopes. You have a high quality scope, should be fine.

csbluesman 24th April 2013 01:54 AM

Yes I'm pretty excited about this scope. The college I attended had these and I was very pleased with them. We also had some of the last style colored hand held Fluke scopes but I really liked the HPs.

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