I've been effectively gifted this mid-80's behemoth, and as it turns out I've got some use for it in the later stages of a project I'm working on. Unfortunately, it's got very low voltage limits, and I don't have the requisite pieces parts to work around that. I work on tube amps at audio frequencies.
I've got two 54001A probes - these are active, with 10k impedance, but a limit of 20V peak. Going to have a hard time scoping a phase inverter with that.
I've also got two 54002A modules, which are 50R impedance and a max 5Vrms. Not a lot of interesting places on a tube amp with that little voltage. I don't have probes for these, but they're BNC.
So. I could build a voltage divider to give me 100:1 attenuation and just hook up the 54001A probes to that when necessary. Upside, cheap. Downside, kinda unwieldy, feels kludgey.
As for the 50R inputs, there's a Tektronics 100x (5k) probe that I can pick up on the auction site pretty cheap. But the following input impedance in most of the places I'd be scoping is 1M or more, so sticking a 5K probe in parallel seems like an excellent way to blow up an input. Or maybe just be super inaccurate.
Third option, pop for a pair of 54003A modules ($40) and a pair of 100x probes from Amazon ($20). Upside, it's clean. Downside, I'm limited to 200V peak.
Which of these makes the most sense? And what was HP thinking, not providing any way to scope anything remotely HV?
I've got two 54001A probes - these are active, with 10k impedance, but a limit of 20V peak. Going to have a hard time scoping a phase inverter with that.
I've also got two 54002A modules, which are 50R impedance and a max 5Vrms. Not a lot of interesting places on a tube amp with that little voltage. I don't have probes for these, but they're BNC.
So. I could build a voltage divider to give me 100:1 attenuation and just hook up the 54001A probes to that when necessary. Upside, cheap. Downside, kinda unwieldy, feels kludgey.
As for the 50R inputs, there's a Tektronics 100x (5k) probe that I can pick up on the auction site pretty cheap. But the following input impedance in most of the places I'd be scoping is 1M or more, so sticking a 5K probe in parallel seems like an excellent way to blow up an input. Or maybe just be super inaccurate.
Third option, pop for a pair of 54003A modules ($40) and a pair of 100x probes from Amazon ($20). Upside, it's clean. Downside, I'm limited to 200V peak.
Which of these makes the most sense? And what was HP thinking, not providing any way to scope anything remotely HV?
You just got an F1 car to move a dump trucks worth of dirt. . . That scope is targeted at high speed low level stuff. Even the 100X probably will cook on the high voltages you are trying to measure. If you were looking at high speed data it would be great and cost a bundle new. if you wanted to see timing issues on a DAC or ADC its a wonderful tool.
The inputs will be really static sensitive and easily destroyed with a small overvoltage.
You could get a better suited scope for your task for what you would spend on the pieces to make that work for you. And a whole lot of bench space back.
The inputs will be really static sensitive and easily destroyed with a small overvoltage.
You could get a better suited scope for your task for what you would spend on the pieces to make that work for you. And a whole lot of bench space back.
Yeah ... I'm thinking that maybe I should try to sell it and use the proceeds to buy a Rigol or Hantek or something. It's not like I'm going to be using a scope for hours every day - I might need to bust it out for a couple hours every month or two. So I'd rather not invest anything at all in it.
I mean, it's huge, heavy, loud, and doesn't do any spectral analysis, which would be handy (and it looks like most cheap modern scopes do). I just wanted to see if I could make it useful before I ditch it.
Love the F1/dump truck analogy. Spot on. Thanks for the advice.
What's the issue with using the 1M inputs for high voltage with standard x10 and x100 'scope probes...
Max input with the 1 Meg module is 2V. Its a pretty serious constraint and fallout from the early high speed sampling network. You will need 1000X probes for looking at a typical tube circuit safely. Those are not common or cheap and pretty clumsy to work with: (P6015A | Tektronix)
For $200- $350 there are lots of fine options in scopes that will just work.
For $200- $350 there are lots of fine options in scopes that will just work.
20 volts ? thats massive compared to some USB scopes where the limit is 3v3 or 5v and if its externally powered maybe 12 volts. One I designed even had 1V A2D !
Most use a standard 1megohm and 10pf input so you can use x10 and x100 probes.
If its not standard input then you need to find scope probe designed for your amp or build your own.
You need to find out current resistive and capacitive input impedance of the scope then add on a series resistor and parallel cap to suit.
A little maths should sort that out.
Most use a standard 1megohm and 10pf input so you can use x10 and x100 probes.
If its not standard input then you need to find scope probe designed for your amp or build your own.
You need to find out current resistive and capacitive input impedance of the scope then add on a series resistor and parallel cap to suit.
A little maths should sort that out.
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The trouble is a scope input that is 2V 1 Meg max in. 10 Meg for 20V, 100 Meg for 200V. And 200V is not enough for working with tube circuits. Its a problem that is resolvable but for the time and money one of your scope kits and pretty easily available probes would make more sense.