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[TCML] Custom GU-81M Vacuum Tube Socket

Greetings all,

As you may recall, a few weeks ago I mentioned wanting a cheaper solution for connecting wires to the studs on the bottom of the GU-81M vacuum tube for my VTTC. Sockets for these tubes can be found on ebay, though they seem somewhat expensive - between $50 and $80 each. That wasn't exactly in my budget so I decided to design a PCB to use as the socket for my tube. This is what I came up with:

- PCB is approximately 80mm in diameter (perhaps 90, I cannot recall off the top of my head) and is 1.6mm thick (a standard PCB thickness)
- There is a slot in the center of the board to allow it to be seated around the glass alignment feature on the base of the tube
- Contact with the tube's studs is achieved using six Keystone #3510 6.4mm (1/4in) PCB-mount fuse clips. These clips are rated for 15A so should do the trick
- External wiring is connected to the board using six Keystone #4966 1/4" PCB-mount male spade terminals. 

That's it. Very simple. The assembled board can be seen here:


Note the original design had the spade terminals mounted to the top side of the PCB (same side as the fuse clips) but I quickly realized that this brought them much too close to the metal tube base. I decided to remove them and place them on the bottom layer instead, thus providing much more clearance. 

If I were to do this again (and who knows, maybe I will), I would probably make the PCB thicker (2.35mm instead of 1.60mm) because it gets a bit flimsy in spots due to the large cutout. It isn't a critical issue but it would be much more rugged if I thickened the board a bit.

I just thought I would share in case anyone might be interested.

Matt, Fairlee VT
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