Dirt Cheap Keithley Bench DMM

[pompeiisneaks]

If anyone is thinking of paying for a pretty nice desktop mm, this one is an amazing price:

http://www.partsconnexion.com/78916a.html

They're normally 5k and this ones going for 350.  I think the company gets them broken, refurbs them and resells for this cheap sometimes.

its a rare event so I was told.  I've never used them before, though so warnings apply :)

~Phil

[eleventeen]

That's an amazing pile of features in one box.

[PRR]

Interesting.

Note that despite the model number, this is 1998 technology. The display is the next thing after a NIXIE tube, not a raster-image display. You "can" connect to PC, but the powerful interface is HPIB which faded from personal computers (and then only on HP) a very long time ago. There is a serial interface but I don't know if it is fully programmable or just triggers.

Read the very huge manual, think what it does for you, think where you may be over-assuming based on newer technology. Spectrum Analysis is cheap now but is not even included in the non-P 2015. The THD is nice, but the base THD+n may be only 0.05% (hardly hi-fi today) and the individual harmonic mode may be slow? The internal generator "only" goes to 20KHz, so you still need another box to tickle your build for supersonic troubles.

It might REALLY shine, as they say, for high-speed testing of mass production devices. If you already have the HPIB/GPIB cables and brains, you can program a series of bleep-boops and verify (or fail) cellfones a dozen a minute. That's probably where these 1/10th-price units are coming out of.

[pompeiisneaks]

Yeah makes sense.  Probably only recently updated I did a search and got some 2015-someodd model, that's likely their latest iteration of the same thing, probably replacing the similar things you mention with more modern accessories... or one would expect such for a 5000 price tag :0

~Phil

[HotBluePlates]

It reminds me of stuff that would be in a military test bench.

The directions things went by 2000 was to replace a technician's knowledge of a circuit to guide troubleshooting in favor of a test bench full of computer-controlled test equipment, which stepped through a troubleshooting tree & associated tests/measurements as directed by a program written by engineers from the company that built that box/piece-of-gear.

The test benches consisted of programmable power supplies, signal & function generators, and various meters/analyzers which could accept programmable control of inputs & outputs. Also present was a computer to run the test routine, an interface between the bench & device-under-test, and a removable-media drive on which the test routine(s) for the item is stored.

Some of the generators and meters/analyzers were quite nice, but the rest of the bench was mid-80's state of the art, and the computer controlling everything was probably early-70's state of the art (100% wire-wrap connections and probably a whopping 128kb of processing power).

When I went through the course to operate one such bench, the bulk of the course was understanding how to troubleshoot the bench to keep it working, how to recognize false-positives and how to troubleshoot problems in the device-under-test the bench wasn't smart enough to find on its own.

The big challenge with any apparently low-priced but possibly obsoleted gear is sorting out whether the things which made it expensive before are worth you shelling out $$ now. Ebay is awash with such gear aged off from industrial use.

[pompeiisneaks]

Sounds painful, but I think this is a bit different, its a pretty well known bench DMM for general use. Here's a currently sold model that is almost identical:

http://www.tek.com/sites/tek.com/files/media/media/resources/2015-2016.pdf 

Tektronix bought them a while back, so its on tek.com. 

here's one for new at some random site, for 4700.

http://www.testequipmentdepot.com/keithley/multimeters/thd-audio-analysis-multimeter-2015.htm

so, I do agree that what you're saying may very well be indicative of some of the things out there on ebay, and I agree that PRR's point about these being possibly a bit older and having less useful specs, I think they're still in the right space for doing work on tube amps no?

~Phil

[jjasilli]

cHECKOUT:


https://www.youtube.com/watch?v=MiXMKgxx_Oc


http://audiokarma.org/forums/index.php?threads/keithley-2015-thd-multimeter.603032/


http://www.quantasylum.com/content/Products/QA400.aspx


http://www.quantasylum.com/content/Products/QA401.aspx