Made a reasonable Ebay score

[at2marty]

I just bought a couple of bench top meters on Ebay that I think turned out to be a pretty reasonable deal.

Both combined were $60 US + $10 US shipping.

The first is a Keithley 175.  The only issue that I have with it so far is it doesn't seem to want to come out of Auto Range.  Selecting a range button doesn't seem to do anything, and "Auto" is shown on the display.  Even with that, checking it on my voltage standard (Fluke 3330B) I get the following measurements.

Voltage Standard Setting            Measured Voltage
100mv                                            99.95mv
1V                                                   1.0002V
10V                                                 10.002V
100V                                               100.02V
999.9999V                                     1000.2V

I would say that is pretty darn accurate for a 20+ year old instrument.  The only other issue that I have is a cracked case.

The second is a Keithley 191.  The main problem that I have with it is fluctuations, ie., the measurement isn't steady.  Here is what I measured.

 Voltage Standard Setting            Measured Voltage
100mv                                           101.948mv - 102.031mv
1V                                                   1.00593V- 1.00636
10V                                                 10.023V - 10.096V
100V                                               100.31V - 100.81V
999.9999V                                     1004.32V - 1004.84V

I'm thinking maybe a few faulty electrolytic caps in this instrument.  Though the measurement is close enough for the hobby stuff that I do, I really want it to be stable.  This should be a fun one to work on.

[retiredcaps]

I would say that is pretty darn accurate for a 20+ year old instrument.  The only other issue that I have is a cracked case.

I bought an used one last year, but beyond powering it on and doing some quick checks, I haven't used it all.  It did match my Fluke 87V in DCV.  And yes, it is easy to crack the case as I found out.

I'm thinking maybe a few faulty electrolytic caps in this instrument.

Yes, possibly contamination on the pcb from leaked caps?

[at2marty]

I let the meters run for a while on my Voltage Standard so that they warm up.  The 175 is pretty much "spot on" and agrees with my HP3468B.  It's kind of nice having two meters that will read down into the mv range with fair accuracy.  The 191 does need a bit of work though.  It still jumps around and though it seems to read fairly accurate, the voltage and resistance readings are not stable.  Perhaps I'll do a "tear apart" video and document what I find with this meter.

Over all, I can't bitch too much for $60 US plus shipping.  These meters will be a nice addition to my bench!