Hi All, what is the best way of repairing an EBF35 VALVE. I have tried tying wire around the base without success. However the valve works well when wrapped in aluminium foil. bowler

Electrolube silver conductive paint

Ebay is one source, WES is another

I’ve had success with exposing the existing copper wire band around the base and repainting the glass with a carbon lacquer mixture. I then usually overcoat it with the gold or red paint as per original. Ground up carbon mixed in quick dry lacquer works well.

I have had an article on that published in "Radio Waves" and with permission in Canada.

Two things happen with metallisation on Philips tubes: One it comes off and two; separation from the earthing pin, due to people dragging instead of prising the tube out by the envelope, breaking the bond.

I used conductive glue on a frame. You need to re-establish contact with pin 1 from the outside. Tube here is still in service. The article should still be buried on one of the Terabyte BU portable drives.

I will send Brad a photo of it; its a Pentagrid ECH35. Pin 1 metallisation. Glue probably Jaycar SKU: 127257. It needs coating.

Marc

The "correct" way would be of course to spray new metallised red paint on the valve including the tie wire that sits at the top of the socket. This wire internally goes to pin1. After it dries you could stencil the valve number on.

However because I am lazy I just firstly wrap aluminium foil around the glass then hold it in place with tape. Then I wrap several turns of bare wire around the foil and tape this down too. The end of the wire is run to pin1 and soldered on. This works fine. I'll also add a small sticker to the valve with the type number written on it. Looks ugly, but it works well.

Photo uploaded to Post 4.

By overcoating the conductive layer with red paint has the same effect and the result is quite nice. I do most of these types valves that I come across in repairs now. The gold finish is little harder to replicate faithfully.

With this one I was lucky, the wire wrap was still tied to pin1. So I placed a collar at the top & secured the spiralled silver wire, all the way down with Araldite (dobs).

Bottom end was soldered to the wire wrap. Only then was the glue applied to the cleaned glass, let set, then coated.

Naturally the tube, albeit experimental at the time, was tested and was good. One does not waste material on a dud.

Photos uploaded to Post 7.

That looks really nice.