Tube burning station

[Mars Amp Repair]

Ya know,
Sometimes the easiest-best solution is right there in front of your face & you can't see the forest for the trees.

I went back to the old scope chassis to try & match up the wires to the transformer (fortunately I had the foresight to leave part of the original wire & insulation on the transformer) & realized the best & easiest thing to do is just use the old scope chassis as my tube burning station. DUH!

It has all the filament wiring to all the tube sockets (all I have to do is wire them to the appropriate pins) and also a crap load of tube sockets already mounted. Fortunately back in the day, they didn't omit the pins on the sockets that they didn't use.
Because of the socket design, they could be rearranged even if they didn't.

The chassis also has many cap-cans in it, too that were all working when I fired it up before I cannibalized it. At the very least I'll just have to put fresh ones in the holes.

The transformer has two mondo high current 6.3V filament windings. It looks like it split them between the octal bases & the 7 & 9 pins tubes. Probably to keep the high current users isolated from the high gain stages. Nice to have 2 so I don't overload the transformer.

This scope also used 4ea 5V4 rectifier tubes that are all wired up as they need to be with silver busses between all the pins for burning 5U4's. All I'd need to do is work up a load for them and this thing is full of hi-wattage wire wound resistors that were used for dropping purposes.

The transformer also has at least 2 center-tapped windings for the HV & a handful of 2 wire secondaries, too.

There are a couple of sockets for 6X4's too. I'll leave them there, but I doubt I'd ever have much need for them as only the older cheaper amps use that rectifier.

The other octal sockets are kind of strewn throughout the chassis & I'll probably have to chassis punch out some of the many 7 pin socket holes & add some, but no big deal there.

I picked this thing up for $3.00 in a yard sale as a curiosity before I started my biz...I never imagined I'd ever be using it for anything.

Thanx LoudThud & all for your input on this issue. I'll keep you posted. glen

[Mars Amp Repair]

tube burning station -pix

Well,
I finally got around to getting this tube burning station going. It ain't very purdy, but it does work like it should.

I used the original Tektronix power transformer for filaments & B+, but had to add a small xformer for the bias supply. It would have been a bit much to divide down from 300V (1/2 CT secondaries) to 80 volts or so.

It worked out well. The Tek xformer only has 2ea 600V ct secondaries & a bunch of 6.3v ones (i suspect for isolation).

For B+ I half wave rectified the CT 600V (unloaded) secondaries. 600V was just too high to bridge rectify & use for B+, the resultant B+ is right about 400Vdc loaded. If ever I decide I need higher B+, I can always go to the bridge, but for now 400Vdc seems fine.

Right now I only have 8 sockets for power tubes wired as 2 quads & of course separate bias adjustments for each quad.

There are also 3 slots that were already wired for rectifier tubes for the scope, so I just left them that way. I may wire them like Mesa does with switchable SIs or tube rect to actually power the rig while burning the rect tubes. I may not even need to burn rect tubes. I haven't decided yet on that. We'll see.

For now I'll just get matched quads & burn them. In time I'll start my own matching for gm & bias.

I've been buying my power tubes preburned & as a result for near full pop. I was just getting disgusted with the high number of early failures I was running into. Esp with JJ's.

I see now that CE dist is offering just the JJ 6L6's with 24hr burning for not much more than the non-burned ones. I am using all kinds of other brands, so I still want to be able to burn them.

cheers, glen

[Mars Amp Repair]

tube burning station underside pic

Ooops, forgot the underside pic. glen

[jrfrond]

I have a simpler solution:

STOP USING J/J's!!!

I won't touch them with a ten-foot pole. I stick to the Sovtek brands and never have problems or complaints, nor do I need to build a tube cooker.

[Mars Amp Repair]

I have a simpler solution:

STOP USING J/J's!!!

I won't touch them with a ten-foot pole. I stick to the Sovtek brands and never have problems or complaints, nor do I need to build a tube cooker.

Agreed;
and how nice and ordered the world would be if everyone shared our personal beliefs & preferences. glen

[jrfrond]

Agreed;
and how nice and ordered the world would be if everyone shared our personal beliefs & preferences. glen

Sure would be Glen!

I will ONLY install J/J's if the customers supply them, and then state CLEARLY on the invoice that we will not warranty ANY damage caused by parts not supplied by us. House rules for everyone who walks through the door.