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| East Tester ET4510 LCR meter |
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| mawyatt:
--- Quote from: GnomeZA on December 13, 2023, 03:41:23 pm --- I think the problems you've spotted could well be down to quality control and may not be intentional or even still present or various scenarios. That said, and to your point, I have my doubts how much you can trust their quality control, "calibration" and specifications. Let's just say, I don't think this going to be like Keithley 2000 (or insert good meter here) you buy 2nd hand, and 30 years later and it is still giving good measurements that are pretty damned accurate. But LCR market doesn't have a well developed middle of the road as far as I can tell. I've done a lot of digging now and I'll admit it is a lot less bleak to me today than it was a week ago. But there isn't much information around, unlike multimeters & scopes, for example. Basically, you either pay enough money to buy a new car or you are stuck with a lot of meh options and trying to make the best of what is around and talking about them here. Because frankly there isn't a good definitive LCR thread even on eevblog that I could find. --- End quote --- Looks as if the design was implemented wrong with BNCs reversed and labeled, so maybe a "Design" QC issue. Agree the old HP34401 and Keithley 2000 were SOTA at their time, and still hold up well today compared to the best DMMs (we have a HP and AG34401) :-+ Anyway, Martin72 posts shows some potential measurement issues with the ET which confirms our initial risk assessment. We had advised against this ET4510 on a PM with someone that wants to build our LCR Meter DC Bias Adapter for DC biased capacitance measurements, and recommended they get the TH2830 instead. These OEM bias adapters are expensive (the Hioki 9268 {$842}, Instek LCR-16 {$1008}), maybe we should make this a product ::) Best, |
| mawyatt:
--- Quote from: nctnico on December 13, 2023, 04:10:48 pm --- --- Quote from: mawyatt on December 13, 2023, 03:34:07 pm ---Some measurement comparisons are good, some slightly different (outside of specs?), and some not even close (100KHz). --- End quote --- Pity the results wheren't included in this thread, but measuring tens of uF at 100kHz is asking for trouble. At 100kHz a 47uF capacitor represent an impedance of 33m Ohm. Good luck trying to measure the amplitude and phase across such a small impedance. When using an LCR meter, it is important to know what the limits of the device are. No matter the price tag. --- End quote --- Exactly KTI (Know Thy Instrument), applicable is ALL INSTRUMENTS, including scopes ;) BTW one important attribute of measuring low impedances accurately is DUT test current, here the IM3536 can supply 100ma, the TH2830 67ma. One measurement by Martin that caught our eye was a 1uF reference cap at 10KHz, and another 1uF at 100KHz. Best, |
| mawyatt:
--- Quote from: Martin72 on December 13, 2023, 03:45:13 pm ---@mawyatt: At the end of the day, it's no different in principle(circuit) to the TH2830, for example, but why it's completely off at 100khz was the reason why I bought another one. I wanted to find out and fix it if possible. But time is short... ;) --- End quote --- Think all these bridge type LCR meters date way back to a General Radio Instrument. In principle agree, in implementation and detail maybe not so!! Were you able to identify the problem area? If so, how was this corrected? Best, |
| mawyatt:
BTW another good tip for those not familiar with how these instruments behave and how they actually work, is the Kelvin clips utilized. The inexpensive ones like supplied with the ET (we have a bunch of these, mostly for DC) are all independent cables, thus any flexure or movement can and will change the cable characteristics (capacitance). We often tape these down to the work bench for better repeatability. The better Kelvin clips are the ones with the BNC adapter fixture, like the TH26011CS (comes with TH2830), these have a single cable that extends the first ~600mm, then a breakout box with individual Hc,Hp,Lp & Lc ~300mm shielded cables to the H and L Kelvin clips. Our experience is these types have less variation in use than the single cable types, and more convenient to use. Best, |
| Martin72:
Hi, --- Quote ---Were you able to identify the problem area? If so, how was this corrected? --- End quote --- These models are available with 10khz, 20khz and 100Khz test frequencies, otherwise they are identical. I suspect that the frequency has simply been increased without regard to the underlying circuitry. Because up to 10khz the meter performs very well, at 1khz there is no big difference at all to all other meters I could test. The supplied cables could also play a role. The problem is that you don't get any documentation (circuit diagram), and the (hidden) calibration menu is not mentioned anywhere. This makes things a bit tedious and time-consuming. |
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