testing 7868s?

[nosaj]

Right. Well, for one thing the drawing aren't in proportion. Note that the height and diameter of the second and third tubes are indicated as the same, though this is clearly not represented accurately in this drawing that is intended to demonstrate proportion.?. So there's that. But more to the point.

I never suggested you could plug different tubes into different bases. I suggested that you could plug a 7868 tube into a typical noval E-9-1 socket. That may or may not be true, but I think it is.

I think his bigger issue is what sockets are available on his hickock 533. He just want to see if they work so he can sell them. I use mine to cull tubes when I get a bunch of them.
And as far as those magnoval and noval sockets I obtained mine from some old Ham equipment.
nosaj
Maybe this pic will put it into perspective

[Justin Thomas]

A Noval and Novar are NOT interchangeable. Novar and Magnoval might "work" if interchanged, but you're pressing your luck. Trust me. My tube tester has all three. No way in hell a 7868 is fitting in a standard 9-pin miniature Noval socket. Look for a nice picture of an Eoco 667 to see all three & then some.

Now, what ARE out there are tubes with a "large button 9-pin base." These will fit in a standard 9-pin socket, but the envelope is wider, so if there is any kind of tube surround, it won't fit. The overhang of the envelope sits on the chassis. The Novar and Magnoval sockets came out at a time when PCBs were beginning to be heavily used, so they're primarily in TV & Radios of the time.

Justin

[Chuck H]

Well that's a big difference then. I think my confusion comes from cross reference information when searching 9 pin sockets and seeing the term "small button" seemingly applied to 7868 tubes. Though it may have an error or out of context. Chalk it up to wishful thinking.

[Randall]

"I would make a little turret board one, myself; just lay out the spacing, drill & seat the turrets, then give em a squeeze so they grip the pins. Quick & dirty, kinda ugly, but, whatever works."

You got my attention, could you be more specific?

[Justin Thomas]

The first time I tried this, I was trying to replace the rectifier switch in my prosonic. It was mounted on a little PCB, and while trying to remove the 12-pin switch, some traces and through-hole plating lifted. I saw the holes in the board were about the same size as a turret, so first I tried putting turrets in, no luck.

So I cut a same-size piece of Garolite, marked the positions of the holes, drilled out the holes (which ended up being pretty close to the spacing on a Compactron tube, maybe a little bigger). I installed the turrets then used wire between turrets on the one side to replace the traces & mounted the switch on the other side.

For a tube socket, I'd cut a piece of board big enough to mount in the inside of the chassis, figure out the pin spacing, drill the 9 holes, turret them, then mount the "socket." I'd leave the body of the turret inside the chassis.

Since tube pins are skinnier than switch terminals, you'd have to narrow the turret holes to make them fit tighter. You could squeeze the body of the turret before staking them. I was thinking you could layer some solder inside the turrets, but, maybe not. Given how some amps tubes melt solder...

Unfortunately, my laptop is out of service so I can't post a picture... I figured this is a cheap solution that you can use as a last resort if you can't get a proper socket...

Justin

Justin

[g1]

I was thinking of breaking apart a standard 12AX type socket and just using the socket pins to solder wires to. Slip the socket pins onto the tube pins, then run the wires to whichever socket you are using in the tube tester.
Sure it's going to take a fair bit of time, but this is only a one time thing right? Otherwise obtain the proper adapter.

[Enzo]

Not for a tube tester, but I have done exactly that to connect up a tube for some fleeting purpose.

[soundmasterg]

Chuck, the 7868's make more power than EL84's and even 7189's also. The El84 is known as a sensitive power tube, meaning that you don't need to drive it much, and the 7868/7591 are also, but not quite as sensitive. A pair should be 44 watts according to the RCA tube manual though I find they are a bit less. They sound really nice though....lots of harmonics and a rich sound similar to an El84 but without the high end emphasis. The vintage 7868 has small pins that are best for the Novar socket, but will work in the Magnoval socket if you adjust it down really small. The EH 7868 is made for the Magnoval socket and will spring the Novar socket out...it will then work in that socket but nothing else with the smaller pins will work in there anymore. The EH's sound and work great btw, though maybe they put out a little less power than vintage 7868's.

Greg

[Randall]

This is a super confusing thread, some conflicting and misleading information here. Justin, I am trying to make an adapter to test a 7868, which my tester has specs for, but I am confused which socket to adapt to. Not sure what your turret mounting inside chassis is about.

Back to the original question, my manual states to use the adapter to test 7868s, but what socket does it adapt to, the mini 9 pin noval or octal? That is the question.

I think I will make it adapt to octal using the pinout conversion I have seen, and see what happens.

[Justin Thomas]

Sorry for any confusion and losing your question... if you just want to make an adapter, then rig up the 9-pin turret adapter on a little board, then run wire from. the bottom to go to your socket on your tester. If you have a pinout conversion to octal, go for it. I would think some thick wire for heaters would go in either your octal or noval socket.

Without seeing an actual adapter, hard to tell which socket your tester used...

Justin

[Randall]

"Without seeing an actual adapter, hard to tell which socket your tester used..."

Precisely.

[mozz]

Original 7868 takes a special socket. The reissue 7868 had fatter pins, they will ruin the original sockets.

[g1]

According to this ebay listing, you go from novar to the 9 pin miniature on your tester:

https://www.ebay.com/itm/1-9Pin-Mini...8090764?_ul=BR

(“1PCS 9 Pin Miniature Male To 9 Pin Novar Female For 7868 Tubes.Hickok adaptor 1050-144 replacement")

[nosaj]

"Without seeing an actual adapter, hard to tell which socket your tester used..."

Precisely.

Read this pdf from the bama site . It states that the adapter will plug into the octal socket. It has everything youd need to build an adapter
http://bama.edebris.com/manuals/hickok/ca4/
nosaj

[g1]

Read this pdf from the bama site . It states that the adapter will plug into the octal socket. It has everything youd need to build an adapter
http://bama.edebris.com/manuals/hickok/ca4/
nosaj

That's the CA4, I thought the SA-4 was different?