While I was developing hardware for Nixie clocks/fixing radios etc., I had a hard time finding some specific tools, so this is to save you the angst. I’m not going to cover the basics like oscilloscopes, isolated power supplies, variacs, heat guns and soldering irons. Most forums will recommend stuff. One thing: if you get an oscilloscope, don’t buy a new one of those small portable chinese jobs – get a good used one like an old Tektronix.
Missing from this list (because I haven’t bought them yet) is a signal generator (a FY6800) and a network analyzer (a NanoVNA).
First up is an electronic load for testing HV power supplies. Most affordable electronic loads are built to test battery chargers, so although they will go to a high current, they can’t handle the voltages. You need a 3710A – pick one up on eBay.
Bench Power Supply
Again, affordable units can’t provide the kind of voltages needed by Nixie tubes, let alone Dekatrons. Get a HSI PS500XT. Fare warning, this is a lot of power – use at your own risk! This will power every Nixie tube you own at the same time. Or one of these IN-28 displays (that’s 250V, 237mA):
You will need a regular bench power supply too – one with a bit more finesse!
So you’ve got a bunch of discretes lying around – resistors, capacitors, inductors, transformers, transistors etc. etc. What do you test them with? Get a MK-328. A truly remarkable device at a ridiculously low price.