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.

23 Apr 2014: I finally got around to a breadboard 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...

Step 1: My 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..

Above 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.
What an outstanding job.. I for one would like to see an article on reforming electrolytics. I have a National NCX-1000 that I'd like to power up &amp; get on the air. I do have access to a Variac and want to take my time with it.. It's a rare rig and in outstanding shape..<br>Excellent article Tim... Keep 'em coming..<br>
I will write an instructable on reforming electrolytics - I promise but it may be some time in coming. We have been planning a move for some time now and it looks like its going to happen this fall. Getting ready for it is taking a lot of time.<br>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.<br>Thanks for the comments.
I love old electronics. there usally built and tested by hand and when i say tested that is also by a tech. Also calibration is done and you even get the instructon manual, and the tech manual to keep it maintaned. With info of test point expected signl and the brake down of a some was called the block diagram to issolate the circats. Even know they were bigger there more accurate then the smaller one because they use good old circuitry. Not that average of two siganl and then? My favorate scopes are tecktronics. It's a 7613 and was born I f i rember in the 1980.Sam year as my Daughter ~30 Yrs. Old. It's a moduler unit This one is a 4 ch. two* two 7A26*2 And a main 7B53A. THank GOD(AAAAAAAAAAH) They were aroud in school and biger more confusing monsters ten this model. Then going to elecronic school back then you learned about eletronic. Even then when you learned digital you accualy learn the desin of a compter from a circutry level ( IT'S A BIG COMPTERRRR who said that. In all fareness though scopes do have to read faster times and signals. And Iguess it is nice to have a smaller scope for service calls. <br>
very good
Very nice job. Did you reuse the old electrolytic capacitors?
Yes I did. I &quot;reformed&quot; them as a precaution and the ones you see on the unit are those from the 1965 scope.<br><br>Cheers and thanks<br>Tim<br>
Maybe I should write an instructable on reforming electrolytics? What do you think?
Please do, reforming old electrolytics would definitely be an advantage!
Yes, may people now just throw out the old ones which is probably not necessary.
Nice Job on a good looking rig! I hope it serves you well and you did a good job on the cable lacing I didn't think that anyone did that anymore (I haven't seen cable lacing since I was in the Navy) <br>Again good work on a job well done<br>Dan
Nice piece of work!<br><br>It's great to see that there are others who are still active in the old technologies.<br>
Wow...you free-soldered all those components....thats amazing

About This Instructable




Bio: 66 yo electronic design engineer, effectively retired. Historically sometimes employed, sometimes self-employed. Have always had a home lab. Just can't let it go.
More by BasinStreetDesign:Inductance/Capacitance Meter Saga Tube Breadboard Tube Power Supply 
Add instructable to: