Fuse Clip for Small Plate Cap Use

[wrenchone]

The small size skirted top caps used by many sweep tubes are troublesome. The current crop of Chinese top caps don't fit very well, or ride high and look dorky (or both), not to mention exposing metal bits at high potential.

Attached is a picture of a partial solution - a commonly available fuse clip. I bought a bag of these on E-pay, and they are available in many configurations from your usual line-up of catalog distributors. The clip fits snugly on the top part of the cap, solving one problem. The fast-on connector provides a secure place to solder the plate wire. What's missing is an insulating shroud that goes all the way down to the glass, but busy little beavers out there will no doubt come up with something. One person in another thread suggested using a silicone distributor cap/spark plug connector boot - not a bad idea, and not all that expensive.

 

[wrenchone]

Here's another view of the fuse clip used on the plate cap of a 6GV6, a typical small/medium size sweep tube using the small skirted plate cap. It's a nice fit on a 6BQ6, too.

 

[wrenchone]

Silicone tubing (~1/2" ID) would also make a nice boot... Some sellers on Ebay are offering "milk tubing" at 2-3 dollars/foot. Mc Master-Carr also sells appropriate silicone tubing in several colors

 

[livingdeliberately]

covering idea...

Solder your wire, then snap an old fuse in place, and then use Plasti-dip.
It comes in many colors and is good insulation.😉
Cheers
mltube

 

[wrenchone]

I have my doubts about plasti-dip standing up to the heat in the long run - also, It'll look lumpy...

 

[w5jag]

That's a nice idea, thanks for sharing it.

Have you tried heat shrink tubing to insulate it?

Even some of the vintage plate caps can ride high. I have a bunch of Millen's and some ride higher than others.

Win W5JAG

 

[wrenchone]

Heat shrink would work, it just won't be very pretty. For the small skirted caps, anything not specifically designed to cover the skirt will ride high. There were some plastic plate caps in the old days that worked, but I haven't seen any of those for 40 years. The fuse clip also fits my newlyacquired Russian Geiger tubes.

 

[Sendy]

Heat shrink is not good idea. I think better is somethink of laboratory ceramic glassware, little ceramic crater or crucible, and silicone glue.

 

[wrenchone]

An idea - the little ceramic cups used with TIG torches would work with this concept, with a little silicone (the hard variety if you can find it) to center the plate wire and anchor it in place.


Edit - Look for "TIG Nozzle" on E-pay to see what I mean. A lot of the items available are pink, but WTF... I've been thinking of doing a petite pink-and-blue amp anyway that I'll call "Ladies Choice", especially as I now have 100 pieces of pink LEDs for pilot lights....

 

[Matt BH]

Hey Wrenchone, I guess the topcaps are quarter inch? If thy are you can use the collet from a control knob. Some of them are phenolic material which should be fine with heat, in which case you amy be able to keep the plastic part of the knob and put a solder tag in the top. Otherwise you can smash the plastic off and use any of the other methods of insulation. Much like this sort of thing:

 

[Hi_Q]

That's a brilliant idea Matt, I wonder if you can drill a small hole near the top for a wire than attach it to the brass insert in such a way that the cap can be fitted to fully insulate.
Les

 

[Matt BH]

That was exactly what I was thinking🙂 If the correct sized knob was chosen its skirt would cover the step in the tophat shaped anode cap aswell. Plus it would look pretty smart.

Only one problem I can see is that kids/people not in the know may think they are controls and wrench the anode cap off the top of the valve.

Cheers Matt.

 

[mashaffer]

My solution would be to use the fuse clip as is and put the whole thing in a cage. I know... spoils the view but I would be very nervous having any kind of removable high voltage line exposed no matter how well insulated.