I always keep an eye on eBay for plug-ins for my HP 143 oscilloscope and even if they don’t turn up, it’s always interesting to see what else is in the category. Some of these are pretty interesting – there’s definitely a lot of project oscilloscopes, but you can get a bargain if you know what to look for. Some of these are definitely pretty rare and unusual, too. Here’s a few that I thought were worth sharing:

There’s an HP differential scope from just a couple years after my 143, the HP 175A oscilloscope. It has a built-in differential vertical input, optional x-y mode and delayed sweep capabilities. It’s priced a little high but some of that’s the vintage condition.

There’s an odd looking HP 1980B Oscilloscope Measurement System, loaded with two dual-channel plug-ins and a dual time base. It screams 1980s  with the membrane keys instead of knobs – although I think it would be very annoying to actually use like that. Plug-in scopes are always a great choice but given I just have to assume plug-ins for this one would be very difficult to come by.

There’s an example of HP’s very first oscilloscope out there, too: the HP 120A. This one is in pretty good cosmetic condition although it’s missing a knob. Great for a collector of test gear, although priced a bit high in unknown condition in my opinion.

The HP 183B is a pretty intimidating looking piece of gear with a 4-channel, 200 MHz vertical amplifier. Looks like it has some functional issues, but it’s got a very cool looking front panel. (Test equipment user interfaces are surprisingly interesting!)

There are plenty of the older HP 141T storage mainframes that come fitted with plug-ins. For some reason they mostly seem to come configured as spectrum analyzers, but that’s also a useful thing to have for a shop. The most common ones are from 0.1-110 MHz and there are a few others. Often in good working condition. One that’s there currently comes with a tracking generator, too.

There were a lot of interesting plug-ins for that series. I’m looking for vertical amplifier plug-ins, but they made a variety of spectrum plug-ins, sampling plug-ins, and even a TDR. I can’t think of any use for that, but it might have some use if you’re designing antennas or transmission lines.

I am still looking for 1400-series vertical amplifier plug-ins, but hopefully someone finds something useful or interesting! I’ll continue posting more round-ups of cool, hard to find and unique test gear that pops up from time to time, too.