For an upcoming experiment, I need to know how accurate my #Keithley 2400 is at nA outputs (God I absolutely love that box… 🥰), but I also wanted to see how well my 6.5digit GDM-9061 multimeter tagged along..

Enter the HP 3458A… 💪🏼😎

Connected them all in series and although the set point on the 2400 is a bit off from reality, it’s own current measurement is bang on. At 20nA 🤯😃 And the 9061 multimeter was in agreement as well, even at such low currents.

Ready for next step, stay tuned 😎😎

#electronics #testandmeasurement #rfengineer #electronicsengineering

The ‘Lambda Diode’ circuit, made from two J-FETs (one P- and one N-Channel) exhibits ‘negative resistance’ and has a ‘hysteresis’ curve when viewed on a curve tracer. A bit like a ‘tunnel diode’, actually.

Circuits like these were a common way to make an oscillator from just a few components, as my next post will show.

I always end up using my analogue #Hameg scope for curve tracing in X-Y mode, it works a lot better than any of the digital scopes I have 🤷🏼‍♂️🙂 In fact, I have yet to experience a digital scope with even a half-decent X-Y mode..

Thanks for the inspiration @va3db 🙂👍🏼

#hamradio #testandmeasurement #hamr #electronics #rfengineer #keithley

It’s #sensorsunday and this weekend I finally got to use my DIY thermal chamber 😃
Along with a Fluke thermocouple meter it turned out really good 👍🏼

Doing temperature test on the 1M #vintage reference resistor - it’s big and heavy, so I left it to soak at the wanted temperature for at least 8hrs, continuously monitoring chamber and device temperature.

Testing at 10,20 and 40C, I found a slightly negative temperature coefficient, but still well inside the 0.02% specification.

My measurements are a bit lower altogether compared with my initial test where I saw precisely 1M. This is due to coupling between the test wires, when entering the thermal chamber. It’s really hard to avoid, even giga-ohms in parallel, will affect the result.

#testandmeasurement #electronics #metrology #electronicsengineering #engineer #fluke #sourcemeasureunit #keithley #keithleyinstruments

Testing my 1988 #burrbrown REF200 - this is likely the first time it sees power since it left the factory 🥹 My #eevblog multimeter and my #keithley #sourcemeasureunit agree: 100uA well within the 0.5%.
The metal can TO-99 housing has a special feat though: it’s specified from -55 to 125C, amazing 😃

#electronics #engineer #electronicsengineering #testansmeasurement

Vintage MMU Repair? It’s Easier With X-Rays

Here's an interesting and detailed teardown and repair of a Keithley 2001 7.5 Digit multimeter that is positively dripping with detail. It's also not every day that we get to see someone using x-ray imaging to evaluate the extent of PCB damage caused by failed electrolytic capacitors.

Dark area is evidence of damage in the multi-layer PCB.

Sadly, this particular model is especially subject to that exact vintage electronics issue: electrolytic capacitor failure and leakage. These failures can lead to destroyed traces, and this particular unit had a number of them (in addition to a few destroyed diodes, just for good measure.) That's where the x-ray machine comes in handy, because some of the damage is hidden inside the multi-layer PCBs.

[Shahriar], perhaps best known as [The Signal Path], narrates the entire process of fixing up the high-quality benchtop multimeter in a video, embedded below (or you can skip directly to the x-ray machine being broken out.) [Shahriar] was able to repair the device, thanks in part to it being in relatively good shape, and having the right tools available. Older electronics are not always so cooperative; the older a device is, the more likely one is to run into physical and logical standards that no longer exist.

#repairhacks #electrolyticcapacitor #keithley #multimeter #repair #vintage #xrays