I am broke, and actually just got fired today (no big loss, shitty job and shitty company) yet somehow I managed to have a pleasing TE moment for very little money !
Found this old WaveTek DM27XT DMM. As crap as it gets as far as DMM performance goes, 2000 count and matching atrocious accuracy. However it's not the point ! I have plenty of much better DMMs in my collection, a dozen Metrix MX 53/54/56, 50.000 counts up to 0,025% accuracy.
No. I am trying to STOP wasting my very scare resources on buying the same instruments over and over again. Have so many of these Metrix DMMs, and so many scopes... like 30+ now ? Lost the count long ago. No, my aim now is to spent my very limited budget, on buying stuff that actually adds value to the lab. Stuff that adds features, enables me in new ways, opens new doors. Stuff that I can use to make things I could not do before. The list of such instruments is very long...
So when I saw that little Wavetek the other day, for only 15 Euros (20 shipped), I could not resist. It features many little cool things I just could not pass for so little money, all in one package, and with a cool brand name on it too, to boot.
Also, back in the day, I used to see in magazines, ads for this style of WaveTek DMM, and the Metrix MX 53/54/56 too. The Metrix were so out of this world that I could only dream of them. Cost a month worth of salary. The WaveTek were cheaper, and there were a wide range of features and performances, to cater for all needs and budgets. Still, even the cheapest one was too much for me.
So, I am glad I can have my revenge now and possess, 25+ years later, one of these WaveTek DMM's.
Anyway, what drew my attention to this DMM was the fact that it looked more like a handheld LCR meter than your traditional general purpose DMM.
Since I can't afford the DE5000 I dream of, I though this little Wavetek would get my into LCR measurements on the cheap. Any LCR meter is better than none at all ! That would get me started for dirt cheap, nothing to lose !
- Main reason I bought it was its low capacitance capabilities : my fancy Metrix DMM go haywire with caps lower in value than say 2 or 5 nF, which drives me nuts. The WaveTek has a 2nF range ! Which means a 1pF resolution ! At the least, it ought to measure properly below 1nF, I thought.
- Measures inductances too, now we are talking ! Lowest range is 2mH so 1uH resolution. Highest range is 20H, if it even exists such a high inductance in the electronic world ?!
- Has a cool 1000VDC range.
- 20A current range rather than the usual 10A range.
- Nice low amps range as well : 200uA, so 100nA resolution !
- Nice ohms range, goes up to 2000 Mohms.
- Nice frequency counter, up to 20MHz !
- Logic probe functionality, handles both TTL and CMOS thresholds. I always wanted a logic probe, now I can play with one.
So really, lots to love in my view, a great addition to the lab for very little money !
Was rather filthy, so took it apart to bits so I could give it a thorough cleaning. This way I could also see how it's put together inside. It's fully packed, I got my money's worth for sure. Two board facing one another. Other than the main chip CPU/LCD driver, I see no less than 10 other DIL IC ! Mostly op-amps of all types and makes, and a few 4000 logic chips. Overall design and construction looks very nice, definitely not your cheapo 5 bucks Chinese DMM.
While I had it apart, cleaned the golden contacts / traces for the rotary switch. Glad I did : they looked clean/like new/ shiny to me, but once I poured IPA on the thing and rubbed it with Q-tips, boy that lifted an awful amount of dirt ! Q-tips came back completely black, had to use 6 of them to get rid of all the crap. So, never trust your eyes... just clean the traces anyway, you never know what condition they really are in....
Put it all back together and tested it. Works just fine. I was mostly interested in the low capacitance capabilities and boy the WaveTek delivered : picked some random disc ceramic caps I had laying around. 150pF ones. DMM reads 30pF with no test leads attached (maybe one of the trimmers inside the instrument would let me zero that out, don't know... ). When I measure the 150pF caps I read 180pF , so spot on ! Tried a few times, on a few different caps... always spot on and reliable. No hesitation no nothing... this thing can measure pF caps just as well as your random DMM can measure uF !
So for this alone, I was over the moon that I bought this thing !
Then tried measuring some inductances ! Picked a small DC motor, a small speaker I recently salvaged from a flat TV, and the secondary winding from a small mains transformer. It works just fine !
I scoped the DMM to see what was going on during a measurement. Both Capacitance and Inductance mode. In both modes of operation it works the same : outputs a fully AC (zero DC offset that I can measure on the scope) signal, triangular, 1kHz or so, low amplitude. Amplitude varies depending on the load the DUT imposes of course. When measuring the scope/probe, hence high Z, I observed a 200mVpp wave. When measuring the inductance of the small speaker, I saw 15+ mVpp.
So it's definitely doing some proper LCR stuff here... which explains why there are so many ICs in the thing.
So, in conclusion... I was right... ADDING new functionality to the lab got me so much more excited than adding yet another scope to my collection !
Being able to measure reliably low pF caps is incredible, and being able to measure inductances is a first. I am over the moon. A new world opens up to me, I can FREAKING MEASURE INDUCTANCES NOW !!!!!
I feel so excited about it, so thrilling.. I feel as excited as I was when I got my very scope 30 years ago !
So this goes to show that even on a shoe string budget, it is possible to add cool stuff to the lab and get excited about it !
The best 20 Euros I have spent IN A LONG TIME !!!
So that now motivates me to continue this policy.... NO N-th scope or DMM... money now only to be spent on devices that add new capabilities to the lab !
A few pics then going to bed.. only 10PM here but somehow I am already knackered
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