Someone kindly gave me a heavy metal box some time last year and have finally got round to building a simple valve tester. It has two HT PSU's using a IRF740 mosfet 0 - 300v, a heater supply switched between 5,6.3,12.6 and adjustable @ 2.5A at a push using a LM317AVH. I've used whatever bits I had apart from the two big pots I got from Birkitts to adjust the HT, at £2.50 each I'm well happy. Sere pic.
For testing rectifiers I'll put the VT on my isolated variable supply for the ac and I've wound a few turns round an existing transformer to give me 5v @ 3A ac.
As you see I've used a jumper panel to switch anode, cathode etc between pins. The amp meter can read either up to 20mA or 100mA, I prefer digital meters but as I had the old panel meters, I used them. I have another HT PSU to make amd some wiring up of the front panel but that's about it. If I get time I will wind a proper transformer, but it will do the job for now.