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| All about Keithley DMM7510. Bugs and features, recipes, advice, notes. |
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| MegaVolt:
--- Quote from: E-Design on April 08, 2020, 08:35:05 pm ---Generally, the AUTO setting changes the input path with different amplifiers which is why you will always see noise differences and bandwidth differences. --- End quote --- Where can I read more about this? I want to understand what exactly is happening. And why it works on the 100 V range but doesn't work on the 1000 V range --- Quote ---I can say this behavior is planed to change on next hardware revision. --- End quote --- Unfortunately my guarantee has already ended :( --- Quote ---Would you consider posting your findings on the Tek forum or engage an applications engineer (Im not one - sorry) ? You might find you can get quicker / better answers by doing so. Just a thought to try and help you out. --- End quote --- I posted this on the tek forum. But in my opinion he is long dead. I would love to talk with someone else, but unfortunately I can’t find the contacts of specialists who understand how the device works. I only come across Keithley's security experts. : (( Can you tell me where to find them? |
| MegaVolt:
Let's try to figure out how the frequency and the aperture parameter for the Digitize mode are set. 1. Sample Rate: It seems we can set any frequency from 1 kHz to 1 MHz. But this is not so. This is easy to see if you try to set the frequency of 999999 Hz. The device will rearrange the frequency 979592. That is, frequency step of the order of 20 kHz. And the next one will be 960,000 Hz. To understand why we will look into the device and find a 48 MHz generator next to the ADC. (why at 50 MHz is a mystery to me.) Accordingly, the period must be a multiple of the period of the generator. For 1 MHz - 48 periods. The next frequency can have 49 periods. This is 979 591.83673 ... Hz or rounded 979592 Hz (which the device shows.) In order to find out how many periods the formula will be set: T = Rounded up (Fgen / Fx). Real sampling rate = Fgen / T; 2. Aperture This parameter did not give in to cracking long enough. In manual mode, when we set the aperture manually by setting the number of microseconds, everything turns out fine. t = 1 μs and the apertura parameter sets the number of averaged samples N. (The device allows you to set up a fractional aperture; maybe it works; maybe not. I haven’t figured it out yet). But there is one caveat. For example, for a frequency of 333334 Hz, as shown above, the period will be exactly 3 μs and it would seem that we can choose a manual aperture 3. But the device says that the maximum aperture is 1/333334 = 2.9999 ... which is <3 μs and does not allow us to set value of 3 mks. only 1 and 2. Now let's move on to the Auto parameter. It works like that. Calculated N = rounding down (T / 48) we get the number of averaged samples. And then we calculate t = rounding down (T / N) As a result, for a frequency of 333334 we get T = 144; N = 3; and t = 48 And for a frequency of 384000 we get T = 125; N = 2; and t = 62 i.e. readings will be taken after 62 then after 63 periods and so on. |
| MegaVolt:
A table with all values of frequencies and parameters T, N, t for Auto mode. |
| MegaVolt:
New KickStart released. https://uk.tek.com/software/kickstart/2-3-0 |
| Electro Fan:
Can someone describe roughly (overall) how the issues discussed in this thread relate to the 6500? For example, when 7510 issues surface are they likely to be similarly present in the 6500 and then fixed in the 6500 after being fixed in the 7510? Or does it work in the reverse sequence? Or some of both sequences? Or are the issues lists for the two models dissimilar enough that the features requests and bug lists have relatively little relationship to one another in terms of being found and addressed? Or something else...? |
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