The raw input voltage can come from a classic transformer/rectifier/filter cap combo.
There is no need to use the converter front-end.
The output voltage and the maximum current can be altered to suit your needs: 500V is probably a bit much for most people
Gotcha! That makes sense. So a really nice way of experiencing with bias and loadlines. That’s cool.
I used some older perf board with larger holes than the stuff you can get today and PC board mount tube sockets. The tube socket pins do not line up correctly with the holes in the board, so I made them fit by bending the pins and enlarging a hole or three. Many of my boards are quite stained up because they have been reused several times. The old stuff with big holes is not easy to find today.
The transformers are Edcor PC board mount transformers with all but one pin on 0.200 mil grid so that all but one drop into the board holes. The oddball pin is bent to fit or the hole is enlarged, I do whatever suits my patience level at the time.
The cheap breadboards you can get today on Amazon have solder pads around each hole. The holes are smaller than what's in my pictures. They come in single sided, and double sided plated through hole versions. I prefer the single sided stuff for tube circuits because they are easier to drill out. I use the double sided stuff for solid state circuits, especially when DIP chips are used. I use SMD to DIP adapter boards (Amazon again) with the tiny parts.
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I could be wrong, but I thought anybody following in George’s footsteps had better add a Fire Extinguisher to their list of required equipment 😀
I just use vero board most of the time ...
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The Hoefer PS500XT does 0 to 500 V at up to 400 mA, with current limiting. It's a switching type power supply, light weight. Good for a tube power amp.
A cheaper model is the Hoefer PS500 which does 0 to 500V at up to 200 mA and with current limiting. It's a linear regulated type supply, heavy. Like $60 on Ebay. Good for the front end stages of a tube power amp or smallish power stages, or screen voltages, or preamp type things. Low noise.
A cheaper model is the Hoefer PS500 which does 0 to 500V at up to 200 mA and with current limiting. It's a linear regulated type supply, heavy. Like $60 on Ebay. Good for the front end stages of a tube power amp or smallish power stages, or screen voltages, or preamp type things. Low noise.
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I never owned a lab supply. Instead, I normally start with building the power supply of whatever I want to build. There definitely are situations where lab supplies would be handy, though.
Bit of timber works great for me, i just know when you have parts moving all over the place you are going to let the magic smoke out. Everything gets screwed to the board with self tapping screws, and screw terminal blocks for the wiring. Takes seconds to mount a part or reconfigure it.
First stage is usually built without the raw power supply, i then use my Heathkit SP-2717 HV supply, or LV bench supplies to work out operating points, which then tells me the voltage and current requirements of the B+ supply before designing it in PSUD2 and ordering the iron.
First stage is usually built without the raw power supply, i then use my Heathkit SP-2717 HV supply, or LV bench supplies to work out operating points, which then tells me the voltage and current requirements of the B+ supply before designing it in PSUD2 and ordering the iron.
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Like so many things, once you have one and use it regularly, you can't live without it. Like you want to find the optimum screen voltage for your output stage, dial it in. The Hoefer supplies are so cheap that I just use them for the actual amplifier supplies now. I put a super quiet fan into the back of the case of course.
15 years ago, I couldn't imagine getting a curve tracer (for tubes), but when I priced tube testers, it was cheaper to get the best curve tracer out there (Tek 576), than a tube tester. Now I look at my tube hobby as pre-stone age and post stone age.
You can get much bigger lab supplies for tube work too, if you want to create EMP events, like you know who. 😀😎
15 years ago, I couldn't imagine getting a curve tracer (for tubes), but when I priced tube testers, it was cheaper to get the best curve tracer out there (Tek 576), than a tube tester. Now I look at my tube hobby as pre-stone age and post stone age.
You can get much bigger lab supplies for tube work too, if you want to create EMP events, like you know who. 😀😎
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Xantrex XDC 12000 Watt supply, for those really BIG tube Amps. You'll need a 3 phase power entrance though.
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I forgot about electrophoresis supplies for tubes It's been mentioned here before. I had to buy three "for parts only" Heathkit IP-17's to cobble together one good one.
It used to be like $50 for a working Heathkit HV supply. I have a couple of them. Two 6L6GC tubes in parallel for the 0-400V regulator. Good for a screen grid supply still. The Hoefer PS500XT handles the B+ for the biggest TV Sweep tubes in P-P. (400 mA, 0-500V)
You'll need the Sorensen/Xantrex or HP supply to do Amps for P-P parallel.
Now they want more $$ on Ebay for those Heathkits than for the Xantrex KW supplies!! Hoefer electrophoresis supplies still seem to be largely unknown. Can get a working PS500 (200 mA, 0-500V) for $60 and a PS500XT for $100.
You'll need the Sorensen/Xantrex or HP supply to do Amps for P-P parallel.
Now they want more $$ on Ebay for those Heathkits than for the Xantrex KW supplies!! Hoefer electrophoresis supplies still seem to be largely unknown. Can get a working PS500 (200 mA, 0-500V) for $60 and a PS500XT for $100.
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Similar for me, but often I just happen to have iron to use, so I build with what I got and then I find a way to make it work.
Who, Me?
I have 4 power supplies that I use for tube work.
The small one is a Knight Kit KG-664. It's like one of those Heathkit supplies except with 4 X 6L6GC's and rated for 200 mA. I got it at a hamfest for $20 about 30 years ago. I rebuilt it a few years ago after a year of storage in an unheated building in weather down to -15 F killed it. I replaced nearly every cap in it, took out the RCA black plate 6L6GC's and installed Chinese.....it IS a power supply not a pricey audio amp. It will run for extended periods of time with the current meter pegged beyond 300 mA without complaint. I sold the RCA's for $150, so I'm up $130 on that supply.
The mid sized unit is a Fluke 407D, zero to 555 volts at a rated 300 mA with a hand full of 807 tubes and a multi tapped power transformer to reduce dissipation. It goes into convulsions at loads over 400 mA, but will behave OK up to nearly 500 mA with a motor run cap across it's output. It was $25 on Ebay in "untested" condition. Shipping was $45. I gambled that the power transformer would be good, but the whole supply worked fine, and still does except for two minor repairs due to me trying to turn the knobs beyond their limits breaking some wires inside. Everything inside it is original.
The Biggie is the HP 6448B like The GIMP and Smoking Amp have. I got it free for fixing some other test equipment. After turning some pots inside mine goes to 650 volts and 1.7 amps before losing regulation. This thing is an old style 60 Hz switcher with 1000uF of output capacitance. The current limiter takes about a second to react, by then there is nothing left of your circuit if you had it up to 650 volts.
I also have a 0-600 volt 1.5 amp Sorensen SMPS, but I haven't fixed it yet. It was also a $25 Ebay find.
When you have an unknown or undocumented tube and you want to find it's limits, you need a power supply for bias, screen, and plate. It helps to have a few big OPT's and a bank of load resistors in one ohm steps. This way you can simply crank up the tube and turn knobs to find what it likes.
Before I got the big power supplies I used a Variac on the input of a 1 KVA 480 volt industrial control transformer hooked up backwards. That fed a solid state bridge and a CLC filter. It was good for about 600 volts at more power than I could use. I did set an OPT on fire finding the limits of a 6LW6 tube when my Radio Shack load resistor blew open.
Just came across this Hoefer PS250 power supply 0-250 V and 0 to 2.5 Amp with current limiting and meters for $2,
another one listed at $50.
HOEFER SCIENTIFIC INSTRUMENTS PS 250/2.5 AMP TRANSPHOR/ELECTROPHORESIS DC POWER | eBay
another one listed at $50.
HOEFER SCIENTIFIC INSTRUMENTS PS 250/2.5 AMP TRANSPHOR/ELECTROPHORESIS DC POWER | eBay
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Variant Epsilon sneezed on it? Maybe they'll let it go for $1.
Might want to ask if the foreign grad student/ technician who was using it has been missing from work lately.
Might want to ask if the foreign grad student/ technician who was using it has been missing from work lately.
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I checked their store, and they have a Lab Jacket for sale at $3 or Best Offer.
I thought maybe they would have a Lab Chair or Bench for sale cheap too.
I thought maybe they would have a Lab Chair or Bench for sale cheap too.