Fluke, old and new

I’ve talked about my old Fluke 77 DMM before, but now I can compare it to my “spanking new”1 Fluke 289 DMM. This thing has it all: a lot of accuracy and precision, features galore, logging, and otherwise nice specs. I got the package with the PC software, data cable, and the Bluetooth/IR connector for the phone app.

I then compared it with the old Fluke 77, which I must’ve bought in 1983 or so, the same year it came out. I checked VDC, ADC, VAC, AAC, and resistance. I also checked the VAC RMS indications at a series of frequencies. As long as I didn’t run up the frequency too much, and stuck to sinus waves, these meters were very close to each other in measurements. Within one percent. Just check out the pictures below.

The Fluke 77 has never been repaired, except for new fuses every now and then, and has never been calibrated. It will probably live longer than me.

First a series of DC measurments with the meters in parallel:

For the current measurements, I connected the meters in series:

Connected in parallel to a sig gen producing a sine wave at 3V RMS, 50 Hz:

Increasing the frequency by an order of magnitude per step quickly left the 77 behind:

When measuring a square wave at 3V RMS, 50 Hz, the 77 gets into trouble and loses its grip on reality:

Sawtooth also confuses the 77, while the 289 is completely unperturbed:

289 has some nice features:

A triangle wave also confuses the 77:

The 77 burden voltage for resistance is around 0.75V, while the 289 uses 2V. Both have around 11 Mohm input resistance on the VDC range:

Even the resistance measurements are pretty darn close to each other:

  1. Well, the 289 was designed and first sold in 2007 or 2008, so “spanking new” means something like “from some time earlier in this millenium”. But, for some reason, Fluke don’t update their products very often. And they don’t really need to, it seems. Except maybe the display could’ve been a bit more modern (it’s weak and washed out). My 289 had a date of June 2015 on the package, and had batteries installed with an expiration date of 2027, so it may have sat on a shelf for two or three years.

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