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Keysight New instruments
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nctnico:

--- Quote from: floobydust on February 28, 2021, 06:41:16 pm ---If I was designing mains SMPS using these multimeters, they would have a short life. They autorange down to mV and get hit with say 370VDC and click clank clunk relays with auto-ranging. So the input stage gets multiple overloads every time. This is differential-mode I am referring to. Then the mux/JFET's get killed and it's a $500 repair bill for the $725 product.

--- End quote ---
Do you really think that the maximum voltage is only allowed in the least sensitive range? That would be an utterly stupid design! DMM designers are smarter than that. The high input impedance alone makes that even at 1000V at the input the amount of energy getting into the input circuitry is minimal and can't do any damage.
SilverSolder:

--- Quote from: nctnico on February 28, 2021, 03:04:00 pm ---
--- Quote from: SilverSolder on February 28, 2021, 02:57:45 pm ---
--- Quote from: exe on February 28, 2021, 02:51:34 pm ---My preferred style would be "short half-rack". Like, Siglent stuff. It nicely fits my table, stackable, and not too deep.

--- End quote ---

For power supply and signal generator yes, but a scope?

--- End quote ---
Yes. If a scope is deep enough I like to stack equipment on top.

--- End quote ---

Makes it a big empty box, when the reason it is big is just to have a display?
ResistorRob:

--- Quote from: bdunham7 on February 27, 2021, 05:31:53 am ---I didn't realize it was a fashion show!
If you want 6.5 digits, BK has the 5493C.  I don't know where you are looking at prices, but the 5493C will be more than the GW-Instek--it's twice as accurate.

--- End quote ---

Why do people in construction spend $50,000 on a new truck when a $10,000 will do the same thing? Or pay extra for nicer wheels, nicer paint, or other unnecessary things? An Ugly Pontiac Aztec will get you from point A to point B, but 99% of people wouldn't want one. I suspect you are in the 1% that would and don't understand aesthetic appeal. I do electronics for fun and having my bench be visually appealing just adds to the enjoyment. I do see beauty in a lot of vintage test equipment but that Fluke meter is just hideous.

The Instek GDM-9061 is 6.5 digit count with 0.0035% accuracy and costs $807 at tequipment.net. BK 5493C is also 6.5 digits and 0.0035% accuracy and costs $834 at the same vendor. So you are mistaken that the BK is cheaper and more accurate. Both have comparable features such as histogram and trending.

Don't get your feelings hurt because one person doesn't like one of your suggestions. I tend to be way more visual than your average person and went my gear to look as nice as well as it functions, so I understand it might be hard to wrap your head around if you are more old school and just want something that works and could care less about what the thing looks like. Thanks for your suggestions, but they just aren't what fits my personal requirements.

Back on topic... being the visual person that I am I really love these new Keysight products. The prices seem good for what you get with the exception of the function gen. At a minimum I think I will definitely pull the trigger on that power supply.
tszaboo:

--- Quote from: wizard69 on February 28, 2021, 04:10:55 pm ---Actually I do want better CAT ratings on bench meters.   I may be 60 but I still remember the stupid things students do in tech classes.   The idea that they are marketing this as a solution for education is what prompted my post.

However in industry, at least the one i work in, "bench" meters do go out onto the plant floor very regularly.   In this case they are either used for calibration+validation or in some cases diagnostics.   Generally they should never get close to high energy circuits but it does happen.   Recent enforcement of regulations for arc flash safety has equipment coming in such that the process control stuff is separated from the heavy 3 phase stuff, usually in separate cabinets.  That makes the meter use "safer" but a better CAT rating would be very welcomed. 

Further if you are at the bench you may have three phase hardware you are working on.   This honestly doesn't happen much today due to the lack of time which leads to a lot of "stuff" going into the recycle bin.   I'm not real thrilled about this but there is little I can do about staffing because personnel says they can't find candidates.

As for safety I'm not sure how it became a specialty need.   Also fused connections are not a guarantee of safety.   I've seen some strange things over the years when it comes to what appeared to be properly installed hardware.

--- End quote ---
For starters its the fuses. A HRC fuse is more expensive. And the enclosure is different. If a fuse blows up in a multimeter, which is in your hand, you might loose a finger. If it blows up in a desktop DMM, worst case you might need to change the pants.
Its much worse, that they might melt the isolation of leads or set them on fire before any of the fuse would act.

And there are practical reasons for this. Unlike a 3.5 digit DMM, here we are dealing with precision. It's only 5.5 digits, but it comes from the same family as the 6.5 and 7.5 digit Agilents. Its entirely possible that there is tradeoff between accuracy and safety, and I give you an example.
Take an ordinary relay, and try to measure 100 mv with it. When you do that with a 6.5 digit DMM, you realize that the energized coil will heat up the connection of the relay, and you have a bunch of tiny thermocouples everywhere  in it. You can either use a latching relay (not safe), Analog switch of FET to switch the signal (not safe), wet contact mercury relays (kills polar bears, somehow) or high end relays that dont fit in the budget.


--- Quote from: Kleinstein on February 28, 2021, 05:14:42 pm ---Students do a lot a crazy things. It is even easier in Europe then in the US: the standard 4 mm plugs nicely fit many European power outlets.

--- End quote ---
Isn't it that way by design?


--- Quote from: pe1oxp on February 28, 2021, 02:25:55 pm ---I can appreciate the new kind of housing, it saves a lot of space on the workbench (depth).
Prices are better for hobby purposes but what when Keysight doesn't sell to private persons anymore...

--- End quote ---
Thats what distributors are for.


--- Quote from: bdunham7 on February 27, 2021, 05:31:53 am ---I didn't realize it was a fashion show!
If you want 6.5 digits, BK has the 5493C.  I don't know where you are looking at prices, but the 5493C will be more than the GW-Instek--it's twice as accurate.

--- End quote ---
just out of curiosity, who is going to calibrate that meter for you? Just as an example, the 34465A has 2 year specification, so you need to calibrate it half as often (if you can live with the accuracy). So while it might cost more, at 3 or 5 years, the cost breaks even.
floobydust:

--- Quote from: nctnico on February 28, 2021, 08:07:16 pm ---
--- Quote from: floobydust on February 28, 2021, 06:41:16 pm ---If I was designing mains SMPS using these multimeters, they would have a short life. They autorange down to mV and get hit with say 370VDC and click clank clunk relays with auto-ranging. So the input stage gets multiple overloads every time. This is differential-mode I am referring to. Then the mux/JFET's get killed and it's a $500 repair bill for the $725 product.

--- End quote ---
Do you really think that the maximum voltage is only allowed in the least sensitive range? That would be an utterly stupid design! DMM designers are smarter than that. The high input impedance alone makes that even at 1000V at the input the amount of energy getting into the input circuitry is minimal and can't do any damage.

--- End quote ---
Adding protection degrades the DMM's specs with the added diode leakage current, resistance (PTC), TVS capacitance.
You can't measure to 100MEG or 1pF with those parts there. For this reason, bench DMM's have less/weaker protection than good handhelds.

Typically the input goes first to the mechanical relays, a series gas-tube (1,500V) + MOV (1,100VC) for ESD protection, then for Lo-DCV range ~100k ohm resistor directly to the CMOS range switch IC/op-amp. High DCV range has the 9.9MEG resistor after the relays. It's pretty much cookie-cutter front-end protection in Keysight/Agilent/HP and Keithley bench multimeters.
So the protection is the clamp-diodes on the CMOS mux or the op-amp with a 100k ohm resistor, should work right?

Nobody has the guts or cash to put one of these through reasonable (true?) overload testing.
Assuming the relay/CMOS mux switching and timing is flawless, you need to do +ve, -ve overload while changing functions and ranges to test for 100% coverage.
I've seen with a DMM as part of ATE connected to a mux, it is common for the (i.e. Labview) program to halt due to some exception or just crappy programming.
So you'd have the DMM sitting on ohms function but the mux is left at another pogo pin with HV -DC on it and then the DMM dies. The Ohms current-source can have weak protection on some models/makes of bench meters.
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