The source isn't important. It's not some fancy audiophile clock if that's what you were wondering.I would prefer the last, or the first if the last is £3k.
What is the source of the signal?
I got the TAP1500 probe off eBay from someone in the UK for a small fraction of the list price. It was practically unused, the accessories kit never opened.Off-topic but you can get very high bandwidth probes for Tek on ebay. I purchased a brand new, 1 GHz one from Singapore I think for a fraction of Tek price. I think they are buying four channel high end scopes and then selling off some of the probes that come with them.
Depends on what the signal actually looks like. I doubt it's a perfect square wave to begin with.Even the best of those traces looks worse than my old Hitachi 'scope with a £10 probe.
I just wanted to know what you used so I can repeat the test with my DSO. The only square signal source I have at hand is the 1 kHz test signal of the scope for adjusting the probe compensation cap. I think about buying a signal generator and the current favorite is the Siglent SDG1062X (60 MHz max) with a rise time of 4.2 ns. Your source seems to have half that risetime though, if I interpret the screenshot correct.The source isn't important. It's not some fancy audiophile clock if that's what you were wondering.
Exactly what I feared ...The probes are from top to bottom, TPP0100 (£50), TPP0250 (£280), TPP0500B (£459), and TAP1500 (£3k).
Yes, but the last one looks more or less OK as a square wave, so why don't the others? Nos 2 & 3 look particularly poor. If my cheap £10 probe can render a 'perfect' square wave, why do 2 & 3 look so poor? What are they doing? Makes no sense to me. Were they properly equalised?Depends on what the signal actually looks like. I doubt it's a perfect square wave to begin with.
The first one just has lower bandwidth. #2 and #3 look broken though.Yes, but the last one looks more or less OK as a square wave, so why don't the others? Nos 2 & 3 look particularly poor. If my cheap £10 probe can render a 'perfect' square wave, why do 2 & 3 look so poor? What are they doing? Makes no sense to me. Were they properly equalised?
Too lazy to read? It's written at the bottom of each screenshot: 24.5758 MHz.What's the fundamental frequency of the square wave? I could figure it out, but I am very lazy.
The source is the clock output an S/PDIF receiver with a series resistor. With the TPP0500B probe before the resistor, it looks like this:The source might be important -- do you (the OP) know that it's a 'clean' square wave source at -- whatever fundamental frequency is being used.
The probes are all 10x. The passive ones were all compensated, the fancy ones automatically. The TAP1500 active probe doesn't have such a setting.Were these adjusted 10x probes?
I doubt your cheap probe can measure a rise time of less than 2 ns, which is what we're looking at here. The distortion is probably the result of interactions between the probe capacitance, source impedance, and PCB + probe ground inductance.If my cheap £10 probe can render a 'perfect' square wave, why do 2 & 3 look so poor?
It's a Tek MDO3054. The TPP0250 and TPP0500B are both sold together with this range of scopes. As I already said, the probes are compensated according to instructions. It's not exactly a difficult procedure.What scope are you using OP? Some of these probes may have specific models they work with. Also, did you compensate the probes?
That's a much longer rise time. Here's my scope's built-in AFG with the TPP0500B probe showing a rise time of about 4 ns:Picoscope stock (i.e., cheap) 10x probe. 1MHz, 50kHz, and 1kHz square wave (built-in signal generator):
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