I have a 600w ham radio amplifier from the 60s. It's a Heathkit SB-200
I'm very proud of it because I bought it in rough condition, and repaired it myself. Replaced all the leaky capacitors and did some other work in there. Now it runs like a dream! It was my first time working with tube gear. The voltages in these things is 2500 volts, that'll kill you dead before you know what happened.
I also have an SB-220 that I got broken. I fixed it up but didn't do a full rebuild on it. It'll do 1200 watts, but I don't need that much power so I haven't used it much. It's in storage. That one is from the late 60s early 70s.
My next oldest device is also ham radio gear, a Kenwood TS-530S from the 80s. There's a lot of solid state stuff inside, plenty of transistors doing all the work. But the final output stage is still a good ole pair of tubes. I bought this in non working condition, and fixed it myself as well. Good fun!