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| Keysight's new 34465A (6.5 digit) and 34470A (7.5 digit) bench multimeters |
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| dr.diesel:
--- Quote from: HighVoltage on October 30, 2017, 11:06:35 am ---Another very important thing to consider is service. (within a warranty or outside of warranty). Try to get any kind of service with Keithley / Tektronix is a horrible experience, to say the least. If it comes to service alone, I would never buy a Keithley / Tektronix instrument again. --- End quote --- I will second this statement. It is unlikely I will choose Keithley/Tek in the future, service (and new product follow-up) is just plain horrible. |
| dr.diesel:
--- Quote from: maxwell3e10 on October 30, 2017, 05:22:23 am ---That is why its so frustrating that the 7510 autozero firmware problem has not been solved. Also the interface is still buggy (my latest success in crashing it involved using temperature secondary measurement). So there is no clear winner. --- End quote --- Even more annoying is that I believe they are simply ignoring the AZ issue. FW 1.6.4c is better, but I also still experience lock-up issues. |
| Dr. Frank:
--- Quote from: fonograph on October 29, 2017, 01:44:11 pm ---How linear are the 34460,61,65 and 70 adc? I read on 65,70 brochure that they are 0.5ppm.Keithley 7510 datasheet shows 1ppm + 1ppm of range. 1. What is adc linearity of 34460? 2. What is adc linearity of 34461? 3. What is adc linearity of 34465? 4. What is adc linearity of 34470? 5. What is this "1ppm +1ppm of range"? I dont understand it,how is it different to just 2ppm linearity? edit: I found another brochure,this one is from Testequity and it says 61 = 2ppm,65 = 1ppm,70 = 0.5ppm Interesting,I thought they 65 and 70 have same adc,I tought only difference is that 70 have ltz1000,correct me if I am wrong but voltage reference doesnt have anything to do with adc linearity? http://www.testequity.com/documents/pdf/keysight/34461A-34465A-34470A-ad.pdf 34460 isnt mentioned there,what is its linearity? --- End quote --- I determined the linearity on two 34465A, and on one 34470A (from HighVoltage): https://www.eevblog.com/forum/testgear/keysight's-new-34465a-(6-5-digit)-and-34470a-(7-5-digit)-bench-multimeters/msg889219/#msg889219, and found no obvious difference between both models, apart from the reference. Usually, the integral linearity is defined as the maximum deviation from a straight line (measurement compensated for offset and gain errors), related to full scale. The datasheet parameter is therefore 1ppm of 10V for all models, whereas the 'ppm of reading' is not so clear. Anyhow, all 3 instruments were well below the specified limits. The 34460A is specified identical to the 461A. Frank |
| Tom45:
For those that did a warmup test of the Keysight meters, was the test from a cold start (plug it in), or from a warm start (in standby for some time and then turned on)? Does the 7510 have a standby mode like the Keysight meters? |
| Dr. Frank:
--- Quote from: Tom45 on October 31, 2017, 01:30:39 am ---For those that did a warmup test of the Keysight meters, was the test from a cold start (plug it in), or from a warm start (in standby for some time and then turned on)? Does the 7510 have a standby mode like the Keysight meters? --- End quote --- The Keysight meters (DMM) all do NOT have a standby mode! The new ones do have a SW switch only, instead of a mechanical mains switch. So even if the StandBy LED is lit, they are completely cold inside. The initial drift in the first about 1/2 - 2h (depending on your stability criterion) is caused mainly by warming up of the resistor networks, but NOT of the voltage references. The ovens of both the LM399H, and also the LTZ1000A warm up within 15 .. 30sec, and the output of the (more complex) LTZ1000 circuit is stable to < 1ppm within about 10 min. See also my latest contribution in the 'Ultra Precision Reference LTZ1000' thread. Frank PS: I attached a warm-up curve of an LTZ1000 module, running at about 50°C. The output really settles within less 10 minuntes, so that should not be the problem in the 34470A, even if this reference is cooked at 90°C. |
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