Products > Test Equipment
R&S NGE100 voltage jumping around
Fixpoint:
--- Quote from: justanothername on October 13, 2020, 09:17:11 am ---Fixpoint, we bought this PSU as replacement for the old analog Hameg 3ch PSUs. As such it was presented to us by R&S when we visited them. Whatever my coworker was trying to do, he searched for an error in his circuit awhile before pinning it down to the new PSU and throwing it back to me. Hes is using the old one again.
And I don't know why a properly built PSU should jump 30mV around at 4V constantly, even when mains is unstable (which is not, of course). I just needed to know if others have the same flaws, seems not, so I will send it back!
I would overlook this when it would be a cheap aliexpress PSU but not for a >1000€ unit.
--- End quote ---
Honestly, I have to wonder what you and your coworkers are doing.
(a) It sounds that you are doing precision stuff but are using a device that is officially not meant for precision stuff (just have a look at the specs). R&S marketing material clearly states that the device is primarily aimed at the educational sector, i. e. schools and universities, and that ROBUSTNESS is its primary feature, NOT accuracy (they say that it will "survive generations of students").
(b) You are complaining that the device does not satisfy an *unspecified* specification, and god knows what your conditions of your measurements were. R&S "only" talks about a specific frequency range? Yes, because that's the industry standard for PSU specs ... I think that's ok.
I would never argue with "a 1000 EUR device must do this or that, even if unspecified". Well ... that may be your opinion, but it will only buy you frustration. The price has nothing to do with anything. If you have SPECIFIC requirements, you must look for EXACTLY the right equipment and ask for the numbers. Yes, the price is a number, but ... the wrong one. :-//
BTW, just for the sake of completeness, I also made a few measurements some weeks ago. Just ballpark, of course. https://www.eevblog.com/forum/testgear/seeking-psu-advice-rohde-schwarz-nge103b-com3-or-keysight-e36313a/msg3231192/#msg3231192
RBBVNL9:
The previous email stresses we should look carefully at what the manufacturers actually specify, claim or say. A few comments on that in the context of this NGE PSU...
--- Quote ---(they say that it will "survive generations of students").
--- End quote ---
To know what 'it' means in the above sentence, we need to look at the R&S brochure. That says "The design of the connectors is robust enough to survive generations of students." So this statement is specifically about the output (banana) connectors of the device. I hope this high robustness level also holds for all other parts, but that is not what they claim.
Just talking "specified" and "unspecified" ;-)
--- Quote ---R&S marketing material clearly states that the device is primarily aimed at the educational sector, i. e. schools and universities
--- End quote ---
This may be your interpretation, but I do not see that written in the market material - at least not the R&S data sheet / brochure for this device (from which you seem to have taken the above statement). There it says "Tailored to be used in education, labs and system racks". (They use this sentence 3 times). So I see three applications listed, including 'labs'. And to be sure, that same word 'labs' is used in the marketing material for the more expensive R&S series like the HMP, HM, NGP and NGP series.
--- Quote ---If you have SPECIFIC requirements, you must look for EXACTLY the right equipment [...]
--- End quote ---
Finally, I agree that if specifications are provided, then we should look at them (and judge on them). Still, I feel a bit uncomfortable that no later than the second sentence in the NGE product procure reads "They offer high efficiency combined with low ripple [...].". That may be a bit misleading for an PSU who's ripple specification (and actual performance) seems considerably below (meaning 'worse than') that of comparable devices.
(I admit we can have a discussion on what 'comparable' means. With N=1 let me just mention the Keysight E36300 Series that specifies voltage ripple and noise of "< 350 uVrms/ 2 mVpp" compared to "typ. < 1.5 mV (RMS), < 20 mV (peak-to-peak) (meas.)" for the NGE.)
Fixpoint:
--- Quote from: RBBVNL9 on October 13, 2020, 01:05:18 pm ---This may be your interpretation, but I do not see that written in the market material - at least not the R&S data sheet / brochure for this device (from which you seem to have taken the above statement). There it says "Tailored to be used in education, labs and system racks". (They use this sentence 3 times). So I see three applications listed, including 'labs'. And to be sure, that same word 'labs' is used in the marketing material for the more expensive R&S series like the HMP, HM, NGP and NGP series.
--- End quote ---
Come on, when we see education listed first, we know what we are dealing with. Marketing will always name the primary use case first. And OF COURSE they mention labs. I mean -- where else do you use a bench power supply? Definitely not on the road. The mention of labs and system racks is self-evident and just marketing speak because it would be a bad idea to mention ONLY education. They want to make money, of course they also mention other uses. Why not use it in a lab? Sure, it works, that's not a wrong statement, and for many labs it will do a great job. It's just not the *primary* use case.
BTW, the RTB2004 is also designed with education in mind. They even have a special education offer.
--- Quote ---Finally, I agree that if specifications are provided, then we should look at them (and judge on them). Still, I feel a bit uncomfortable that no later than the second sentence in the NGE product procure reads "They offer high efficiency combined with low ripple [...].". That may be a bit misleading for an PSU who's ripple specification (and actual performance) seems considerably below (meaning 'worse than') that of comparable devices.
--- End quote ---
Again, marketing speak ... Of course they will say "low ripple", just because it doesn't have high ripple. Which is true, it doesn't. Please let's remember that the NGE is not a bad instrument. And let's be reasonable -- the NGE indeed has low ripple, just not VERY low ripple. There are many PSUs that don't have low ripple, with those you have pretty different numbers than with the NGE.
RBBVNL9:
Whatever reasons R&S have to write that this device is "Tailored to be used in education, labs and system racks", if they do so, we cannot disqualify someone for using it in a lab.
I agree we cannot expect unusually high performance from an instrument when this is not specified. But that does not mean that ‘anything goes’ for a device that is marketed for use in a lab. If justanothername’s unit is indeed jumps up and down by 30 to 40mV, is that OK? And, just suppose, that the jumps are 100mV, would that be OK? Of a full volt jump, is that OK, even when this performance criteria is not specified?
I’m not saying I have the wisdom of saying when something is still OK and when it is not, but I cannot blame someone for bringing up the question, or wanting to know whether his of her own unit behaves differently from that of others.
switchabl:
Without weighing in on the more general discussion: I am not sure that fluctuations <20Hz are completely unspecified. I would think they should not exceed the "programming accuracy" of < 0.1% + 30mV.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version