vacuum tube top question - Printable Version

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vacuum tube top question - radionoob - 12-27-2010

Hi all,

I'm getting around to restoring my 38-7, and I've noticed a problem with a vacuum tube.

Coming out of the top of the tube is a very small wire. On top of that is a little metal cap, which is connected to wire that continues the circuit.

My problem is that this cap won't stay on the tube, and so the circuit becomes broken.

How can I keep that cap on top of the tube?

Im assuming the little wire coming from the vacuum tube has to touch the cap to keep the circuit connected.

If this doesn't make sense to you guys, I'll try to take some pics to explain better.
Thanks for your help.

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Re: vacuum tube top question - exray - 12-27-2010

You should be able to resolder the cap to the wire. If the wire is too short you can solder on an extension of small wire.

Heat up the top cap separately and shake off the old solder. You should see a little pinhole where the wire goes thru.

Hope that helps.

-Bill

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Re: vacuum tube top question - Alan Douglas - 12-29-2010

Put a little Elmer's glue inside the cap. Pre-tin the wire coming out of the tube. Place the cap on the tube and rotate it until it fits snugly (I'm assuming the old cement is still in place inside the cap. There will be one "best" position, where the cap was originally). Now use a hot iron and add a little solder to the depression in the top of the cap, where the wire is poking through. Do it really quickly. Then let the glue set for a day.

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