Print PDF
Favorite
Email
A what?! Isn't a “power supply” that miscellaneous piece of a project that you ignore until you can't anymore, then patch it together as quick as you can so you can get back to the fun parts? And a power supply for tubes? That just amounts to a fat transformer, a bridge rectifier and a filter cap almost as fat as the afore-mentioned transformer, right? Usually.
In this case, I felt compelled by a pile of tube-related parts I had harvested after ripping an old 500-series Tek scope apart, a wish to play with test tube circuits (test-tube circuits?) on the bench with a handy bench power supply built just for this purpose, and not much else to do. In order to construct some tube circuits on a “breadboard” style set up and be able to manipulate or dial-up the supply voltages at will, I would need to have a bench supply that would put out low as well as high voltages, not to mention grid bias voltages, filament power and would display what those voltages were. Being able to also display the current drawn from any of those would be a bonus. It might also look pretty cool.
As I said I wanted to put together circuits that were “breadboard” style, sort of like those awful-but-ubiquitous (don't get me started) white push-in proto-boards that you see everywhere anybody is messing around with electronics. But for tubes. At least as far as capability goes; I don't really mean to use those white things for circuits with 350 V floating around them. But the breadboard part is for another instructable and not covered here.
By the way, the term “breadboard” comes from the 1920's and 1930's when young people were just getting into an exciting new thing called “radio”. They were building their own crystal radio receivers from scratch and when they needed a platform to mount coils and cat-whiskers and such to, the handiest way to do it many times was to “borrow” a real honest-to-goodness bread-cutting board from Mom's kitchen, sometimes when she wasn't looking. I'm just guessing, but She probably wasn't too impressed. Yeah, hackers existed then, too, and the term just stuck.
I also assumed that I would need to build it for minimal cash outlay, hence the old tube-based scope.
First, my source of parts...
In this case, I felt compelled by a pile of tube-related parts I had harvested after ripping an old 500-series Tek scope apart, a wish to play with test tube circuits (test-tube circuits?) on the bench with a handy bench power supply built just for this purpose, and not much else to do. In order to construct some tube circuits on a “breadboard” style set up and be able to manipulate or dial-up the supply voltages at will, I would need to have a bench supply that would put out low as well as high voltages, not to mention grid bias voltages, filament power and would display what those voltages were. Being able to also display the current drawn from any of those would be a bonus. It might also look pretty cool.
As I said I wanted to put together circuits that were “breadboard” style, sort of like those awful-but-ubiquitous (don't get me started) white push-in proto-boards that you see everywhere anybody is messing around with electronics. But for tubes. At least as far as capability goes; I don't really mean to use those white things for circuits with 350 V floating around them. But the breadboard part is for another instructable and not covered here.
By the way, the term “breadboard” comes from the 1920's and 1930's when young people were just getting into an exciting new thing called “radio”. They were building their own crystal radio receivers from scratch and when they needed a platform to mount coils and cat-whiskers and such to, the handiest way to do it many times was to “borrow” a real honest-to-goodness bread-cutting board from Mom's kitchen, sometimes when she wasn't looking. I'm just guessing, but She probably wasn't too impressed. Yeah, hackers existed then, too, and the term just stuck.
I also assumed that I would need to build it for minimal cash outlay, hence the old tube-based scope.
First, my source of parts...
Remove these ads by
Signing UpStep 1My Source of Parts
Firstly, this wouldn't have happened if I didn't have at least one of those 1960's-era Tek 500-series scopes to take apart. These classic monsters, which were the workhorses of the professional industry during the 1950's and '60's and into the '70s, are a bona-fide treasure trove of tube-related parts. I harvested from one, the power transformer, many tube sockets, some 2-Watt resistors, large, high-voltage filter caps and some military-grade pots as well as those lovely front panel knobs. Oh, and the tubes came out of there as well. I took about 50 tubes out of a Tek 545, mostly 6DJ8's, 12AX7's, 6AU6's, 12B4's and a couple of lovely 6080 dual power triodes.
These monsters are entirely fixable by any knowledgeable hobbyist with a spare carcass for parts and will still put in a decade or two of good service as long as you don't mind having a 500-Watt heater next to your bench and giving it at least half an hours worth of warm-up time before use.
They can be had for not much more than a song when you can find one. The surplus houses will list them for $100 - $150 but best to try the swap-meets or ham-fest events first. Most of them are swept up by collectors (one Tek freak has almost 100 of them stacked up) but they come available from time to time. Depending on model, service manuals can usually be had online but otherwise are sold for about $25 - $35..
Below is a couple of shots of one of the ones I have and is not the one which I have cannibalized for this project, a Tek 545, but is a Tek 535 which is very similar.
These monsters are entirely fixable by any knowledgeable hobbyist with a spare carcass for parts and will still put in a decade or two of good service as long as you don't mind having a 500-Watt heater next to your bench and giving it at least half an hours worth of warm-up time before use.
They can be had for not much more than a song when you can find one. The surplus houses will list them for $100 - $150 but best to try the swap-meets or ham-fest events first. Most of them are swept up by collectors (one Tek freak has almost 100 of them stacked up) but they come available from time to time. Depending on model, service manuals can usually be had online but otherwise are sold for about $25 - $35..
Below is a couple of shots of one of the ones I have and is not the one which I have cannibalized for this project, a Tek 545, but is a Tek 535 which is very similar.
| « Previous Step | Download PDFView All Steps | Next Step » |
Excellent article Tim... Keep 'em coming..
From what I read about the NCX-1000 it is well liked. I am not a ham, myself, just a listener with a couple of receivers, a Grundig Satellit 800 that I love and an old Eddystone communications receiver which still works like new.
Thanks for the comments.
Cheers and thanks
Tim
Again good work on a job well done
Dan
It's great to see that there are others who are still active in the old technologies.