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12 pin compactron pinout dimensions ?

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The circle diameter that the pins are located on appears to be .75". I checked a 6JM6, but the pins are not located 180 degrees from each other, so they measure ~.790 - .040 pin dia. = .75.

Oddly, the Wikipedia entry says the pins are on a 27mm circle, for a B12C socket.

jeff
 
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Yup, and there are different dims reported elsewhere, which is why I'm looking for a mechanical drawing.

The circle radius for a PCB mount socket won't work. I'm looking to connect the tube directly to pcb so spacing needs to be right on or there's risk of cracking the glass when plugging it in.

Thanks
 
I'm looking to connect the tube directly to pcb so spacing needs to be right on or there's risk of cracking the glass when plugging it in.

To me, that sounds like a recipe for disaster. There's got to be a way to make either a chassis mount or PCB mount socket work.

pin diam = 3/64" = .05" = 1.3mm

I have several different compactron tubes here, and all the pins measure .040".

jeff
 
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Hey guys ! Thanks a lot for taking the time to measure !

Still, one problem is getting the pin location on the circle. As Vinyl58 said above, the pins are not directly opposite each other through the center-line, but offset. So a drawing showing radius angle from pin to pin would help a lot. I've never seen one, but find it hard to imagine the manufacturers never published them. They've got to be out there . . . . .somewhere.
 
B12c Duodecar B12C base (IEC 67-I-17a) Compactron T-9 construction/E12-70 base

19.1mm (3/4") circle,
11x 27.7° then gap between pins 12 & 1
pin diameter 1.02mm

Abbildungen - Figures
 

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B12c Duodecar B12C base (IEC 67-I-17a) Compactron T-9 construction/E12-70 base

19.1mm (3/4") circle,
11x 27.7° then gap between pins 12 & 1
pin diameter 1.02mm

Abbildungen - Figures

Thanks for posting that. The angle is the missing key to the compactron puzzle. No surprise, the Wikipedia entry wrongly states the pin circle diameter as being 27mm, when it's really 19.1mm.

jeff
 
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Hey, thanks Payloadde ! That was the ticket!

OK, this is how i figured it out in ExpressPCB. Started with a large 5 in.radius circle > calculate chord length for 13 sided polygon > circles at chord length > lines from intersects to center > then add actual pin circle diameter (the little white one at center) . Later on I'll finish it with pads for pin sockets and post the file here. (Sorry BMike, I've haven't used DesignSpark.)

Thanks again guys!
 

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Compactron was GE's trademarked name for the 12 pin duodecar base also used by RCA and others. All 12 pin tubes in the US have .040 inch pins. The pin angle is 27.69 degrees, 13 pins with one missing.

All Compactrons were technically 12 pin tubes, but the trademarked name did become rather generically used to refer to all the multi element tubes, and even some 9 pin sweep tubes. I don't remember ever seeing this done in GE's own literature, and RCA never used the Compactron word, except when making and branding tubes for GE.

GE had been using the 'tron trademark since the 1940's. Their 807 and other transmitting tubes were Pliotrons. Their mercury vapor rectifiers were Phanotrons. There were others I don't recall.

The 12 pin base was not common outside the US. Many of GE's compactrons were just two or three tubes that were already in their catalog stuffed into a single envelope to counter the solid state revolution. I am including a list that GE published in 1964.

The 9 pin base was used world wide with two common flavors. Neither have been called "Compactron" in manufacturer printed literature.

The Novar is the large 9 pin base common in the USA. It has .040 inch pins on a .687 inch circle.

The Magnoval is the large 9 pin base common in Europe, Japan and Korea. It has .050 inch pins on a .687 inch circle. The pin to pin angle is 36 degrees, 10 pins with one missing.
 

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On many of the listed tube basings there are pins with the 'IC' designation which I'd guess stands for internal connection. On some, the letters stand out in line with a single pin and others are set in between which I would take to mean there is some sort of difference, perhaps that the latter ones are connected together.

I've seen tubes with pins not connected to anything at all. Did they put the designations there to let users feel they weren't just flapping in the breeze?
 
Most of the time there is nothing actually connected to these pins. It is intended that nobody actually connect anything to these pins since ANY manufacturer is free to actually connect something to them in the future.

Many sweep tubes that do not have a plate cap reserve the pins on either side of the plate pin in this manner to avoid the possibility of an arc in the socket.

Sometimes a manufacturer will use one of the IC pins for an internal tie point, while another manufacturer of the exact same tube, or a different batch of the same tube from the same manufacturer will not. An example of this is the 35LR6 sweep tube. SOME Sylvania made tubes used pin 7 for the center tap of the heater. The tube actually contains two 17.5 volt heaters wired in series. I save about 20 of these and they do indeed work quite well from 17.5 volts, however I have some more Sylvanias and some RCA's with no connection to these pins.

Some Compactrons with multiple tubes inside will use one of the IC pins for the connection between the two heaters. Again, this can be sporadic between different versions of the same tube number. Some of the dual tubes that have a small sweep pentode and a damper diode in the same envelope do this since the guts come from other tubes. The heater tap is not symmetrical. The sweep tube has a higher voltage heater, but both draw the same current since they are intended to operate in a series heater string.

Some Compactrons with multiple tubes inside will use one of these pins for structure support. The pin may or may not actually be connected to anything inside, but may draw current if a positive voltage is applied to it.

Sometimes the IC connection can be tied to a shield that is physically inside the tube. This is often the case when there is a similar version of the same tube without the shield. There is a multi unit Compactron like this, but I can't remember what it was.

In any case the IC pins are a wild card, and you can never tell exactly what will be connected to these pins. The only time I would use them is when you are making a one off for yourself and you have a lifetime supply of spare tubes that you can verify before building.
 
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Over the years I've seen some recommend cutting off unused (or duplicate) pins - (particularly for hi mu or high gm tubes) as a help in lowering rf and radiated noise pickup problems. I see it as a danger to the glass (when the pin snaps) but wonder if there really is any EE benefit.
 
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Is there a mistake in this drawing where DIA 16.5mm should be 26.5mm, since the DIA of pins is 19mm which is obviously larger than 16.5mm? Check the precision if you wish.
 

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