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| R&S NGE100 voltage jumping around |
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| RBBVNL9:
Oh, wait a moment! All this time, we have all been writing that this voltage stability aspect was not specified for this device. But I think that R&S actually DOES specify this!!! Look at the data sheet, page 8: Programming accuracy: Voltage. ± (% of output + offset). < 0.1% + 30 mV So at 4V output, the output should be within 34 mV from the set value (correct me if I am wrong). If so (and assuming his measurements are OK) then justanothername's unit is on the edge of the specs, perhaps just under, perhaps just above. In the specs, no load condition is indicated, but I think it is reasonable to assume that this specification must be met under load. Would be interested to see this. PS: The data sheet programming accuracy for current, and also specifies the read back accuracy. I also noted that all specs are valid at +23°C (–3°C/+ 7°C) after 30 minutes warm-up time. There is also a lot more small print one might want to read to understand what these specifications mean. |
| RBBVNL9:
@switchabl: our posts crossed in cyberspace ;-) |
| RBBVNL9:
Repeating the above specs: at 4V output, the output should be within 34 mV from the set value (correct me if I am wrong). So, the output may 'slowly' fluctuate up to 68 mV, if that fluctuation is precisely around the set value. (Fast fluctuations are covered by the stricter ripple and noise specs that apply from 20Hz on.) Just just measured my NGE at 4V with a 2.5A load, out of curiosity. A did a 1 hour, 1 second interval output voltage measurement (using the setup I discussed above). Let us for the sake of the argument suppose this measurement is accurate (do not want to go down this road)... My measurements varied from 37.5mV below the set value to 2.9mV below the set value. (It never goes up to or above the set value.) My results would be about same as the allowed deviation, or a bit above (assuming they are valid for a device under such load). The graphs I see suggest that some kind of switching is going on (some minutes high values, then some minutes low values, and so on). But again, I am not claiming my measurements are in fact accurate. And if they were, we would still need to look at all the fine print in the data sheet... |
| switchabl:
It is not stated explicitly (as far as I can see), but I would assume that the programming accuracy is specified with no load. So you would have to allow for another 0.1%+20mV due to load regulation. (At least for the older Agilent power supplies, I remember that the performance verification procedure had you checking the programming accuracy with no load, and then verify load regulation separately.) Overall, the specs of the NGE100 don't look too impressive to me. I don't think I would want one as my go-to bench supply for design work (especially analog). It is definitely not in the same league as the more expensive Keysight E36300 or R&S HMP series (or an old Agilent E363x at that). That being said, for many applications it will still be more than good enough and it packs 3 independent channels with a decent amount of power in a compact box. If you qualify for an education discount the price might be quite attractive as well. |
| Fixpoint:
--- Quote from: switchabl on October 13, 2020, 06:14:24 pm ---Overall, the specs of the NGE100 don't look too impressive to me. --- End quote --- Yes, that's right, the specs are not "impressive". If impressive specs is what you are looking for, this instrument is not for you. I personally use this instrument because of its usability and because it has 3 channels (which I indeed make use of, depending on the project). I don't care about 10 or 20 mVpp ripple, but I care about usability. And I like the NGE's UI and UX very much. (It's also a good-looking PSU, if that makes sense.) And, of course, it should protect my stuff from the occasional short, which it does very well. I am using it on analog VCO stuff, and for now everything works fine. |
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