Re: Tek 2465b two probes showing slightly different voltages and phases
Hi Mark,toggle quoted messageShow quoted text
Your data helps a great deal.
So, at 5MHz there is a 4% gain difference. For a 10:1 probe, that's "high frequency", so the gain there is sensitive to the probe's adjustment. If that 4% bothers you, just tweak one or the other probe. I doubt you'll see a huge effect on the 1kHz response you used to adjust the probe in the first place.
Terminating the probe in 50 ohms tells you very little besides "don't do that." The voltage divide ratios for two different probes will produce quite different scale factors at your relatively high 5MHz frequency. It's important to keep in mind that a probe is not just a cable, nor is it a cable with an RC. It's a specially-designed lossy cable with (generally) an equalizer (in high-bandwidth probes). Different probe types have different equalizing networks, so they'll present different impedances. The voltage dividers formed with a 50 ohm termination will be different (and not at all flat with frequency).
Now, as to your phase difference: I just took note of the probe model numbers. I'm confused: The P6019 is a current probe. Is that a typo? Would you confirm?
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford, CA 94305-4070
On 12/30/2020 18:16, Mark Hatch wrote: