Working Keithley 196 U$$250 is a good deal? - Page 1
Forum section: electronics / testgear

author: vmiguel
author_rank: Newbie
timestamp: February 28, 2019, 12:37:17 pm
content: I have an opportunity to buy a Keithley 196 for U$ $175,00 with freight is gonna cost me U$ $250,00It's calibrated, the only issue is that the latch mechanism in the switch button does not work, so only the read plugs are working. to be fully functional the switch must be changed.Should I go for it?Thanks,Vini

author: TiN
author_rank: Super Contributor
timestamp: February 28, 2019, 12:46:36 pm
content: For 250$ you can find K2000 or HP34401, if you patient and willing to take some risks.

author: pigrew
author_rank: Frequent Contributor
timestamp: February 28, 2019, 01:17:13 pm
content: I agree with TiN that your money is probably better spent on a newer unit.However, the 196 does have offset compensated ohms measurement, which the other meters lack.

author: LapTop006
author_rank: Unknown
timestamp: February 28, 2019, 01:56:54 pm
content: I bought one for the work lab a while back, works fine.It makes a nice meter that won't walk. Sure it's no Keithley 2000/6500, but I like it.(Yes I was somewhat cheating for this photo)

author: EEVblog
author_rank: Unknown
timestamp: February 28, 2019, 02:03:03 pm
content: They go for a fair bit cheaper:

author: coromonadalix
author_rank: Super Contributor
timestamp: March 01, 2019, 02:49:49 am
content: Snatched the 115$ one, but the top case is broken, miss a big piece, want to find a donnorThey have the same case in many models ...

author: kawal
author_rank: Frequent Contributor
timestamp: March 15, 2019, 04:25:29 pm
content: I was looking at that one myself. Glad you got it. Post a review when you get it.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 15, 2019, 04:48:19 pm
content: Backed the calibration chip and re-write it a few times, it`s on the b14 firmware, i will upgrade it to b17Searching for precision resistors for a full range calibration IE : the manual ask for 190, 1.9k 19k, 190k, 1,9 meg, 19 and 190 megs, butIm going for: 300 ohms, 3k, 30k, 300k, 3meg, 30 meg and 300 megs, since the dmm will top at 3,030 value display Boy they are priceyyyyyyyy 8-10$ a resistor at 0.02%, i do know you can calibrate it, with known resistors values and adjust the dmm accordingly.Checking some Vishay foil resistors ...Doing a Full capacitors recap, there`s only 1 chimical cap and 1 tantalum cap on the meter board, very niceSad to be unable to reverse the calibration chip coding loll , i`ll push the 196 against my recently calibrated 34401a i`m sellingThe front rear switch is not good, i`ll remove it and the rear input terminal xformer coil(s) and set it permanently for a ``front`` use.Finally I need to find a top case (wtb post), since it miss a big part on the rear, thats why i haven`t paid a lot for it loll I`m the final user loll

author: Kleinstein
author_rank: Super Contributor
timestamp: March 15, 2019, 05:22:46 pm
content: The 196 Ohms modes don't use constant current sources, but a kind of bridge circuit with the DUT and reference resistor in series. So they will not necessary have the best accuracy at the full scale range. It's more like best accuracy near the center of the range, or the value of the reference resistors.A value near 300 Ohms and 3 K may be OK, but 300 K ... 300 Meg are likely not such a good idea.For the 300 M range I would even prefer some 50 M.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 15, 2019, 07:03:43 pm
content: Can't remember which one I had, but that sure looks like the one where the power supply pass element runs at the surface temperature of the sun. Even with a DIY heat sink it ran hot. The unit wasn't all that stable either. Sold it cheap. Might not be the same unit, but be sure to check how hot the supply runs.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 15, 2019, 08:44:04 pm
content: okay i should use the same values in the manual ... thks

author: macboy
author_rank: Super Contributor
timestamp: March 21, 2019, 04:09:40 pm
content: Quote from: pigrew on February 28, 2019, 01:17:13 pmAlso keep an eye out for HP/Agilent/Keysight 34970A. This is a "data logger" which means it is a DMM with built in switch/mux system (OK, technically it is a switch/mux with a built in DMM). The DMM was an option, so make sure it (and a 34901A mux card) is present before buying. Most have it. The DMM is a 6.5 digit one, and is almost identical to the 34401A in both functionality and specifications, but itaddsthings like offset compensated Ohms and temperature measurements (with thermocouples, RTDs, etc.). The current measurement might be slightly limited (1 A max?) but check the specs yourself if it's important. These are usually cheaper than 34401A DMMs because of lower demand, even though their original cost was much higher.One good (?) thing about the 196 is the through-hole construction which generally makes repair easier. And few people have ever cursed at a big bright 7-segment LED display. That is usually reserved for poorly lit LCDs, like what HP liked to use in the late 70's-80's. sigh.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 21, 2019, 07:11:38 pm
content: QuoteJust checked on Fleabay, they sell pretty high, even with no card installed?

author: coromonadalix
author_rank: Super Contributor
timestamp: March 27, 2019, 09:01:27 am
content: the 34970a dmm section goes to 1 amp, 300vdc, 300vac, 100meg ohms, and rated at 0.004% precisionthe dmm section is optional, have to be careful if you buy theses units