29-10-2015, 08:07 PM
You actually need methylated spirit to dissolve the cement which was used to fix the valve base to the bottle. As Brian says, it was a mixture of shellac and wood flour. (It won't have been cellulose shellac so thinners won't dissolve it).
If ever you need to take a base off to replace with one of a different type, as I've discovered to my cost, never simply unsolder the wires and remove the base expecting the wires to obediently stay where they are in a nice ring formation. The 'pinch' which is recessed into the base of the bottle is flat - not circular, and once the base is pulled off, the wires take on a life of their own and spring into whichever random formation they have a mind to. Hence, all you can then identify is the heaters. The anode, cathode, grid, whatever could be any combination.
What I therefore do is make two cuts around the old base with a Dremel & cutting disc to free up a ring from the wall of the valve base, then cut through the ring and discard it, to expose all of the wires. You can then see which wire goes to which pin of the valve base, tie on a little label to identify it, then you can safely unsolder all the wires and remove the old base, ready to extend the wires to the pins of the new alternative base before fixing it to the bottle and soldering the wires in each pin. I then remove the labels from the wires and slip coloured sleeving over the wires.
To illustrate what I meanI've attached a few pics of an EBL1 side-contact valve being converted into an EBL31 by substituting an octal base. This is all irrelevant in your present case as all you are intending to do is to remove the bottle, snip off wires (unless you intend to keep the heaters connected for appearance sake, if intact), and to fit silicon rectifiers internally in the valve base across the appropriate pins, so you don't need to know which wire was which, and the heater wires can be identified come what may, if the heater is still intact.
You certainly like multiple challenges Nick!
Good luck with it.
If ever you need to take a base off to replace with one of a different type, as I've discovered to my cost, never simply unsolder the wires and remove the base expecting the wires to obediently stay where they are in a nice ring formation. The 'pinch' which is recessed into the base of the bottle is flat - not circular, and once the base is pulled off, the wires take on a life of their own and spring into whichever random formation they have a mind to. Hence, all you can then identify is the heaters. The anode, cathode, grid, whatever could be any combination.
What I therefore do is make two cuts around the old base with a Dremel & cutting disc to free up a ring from the wall of the valve base, then cut through the ring and discard it, to expose all of the wires. You can then see which wire goes to which pin of the valve base, tie on a little label to identify it, then you can safely unsolder all the wires and remove the old base, ready to extend the wires to the pins of the new alternative base before fixing it to the bottle and soldering the wires in each pin. I then remove the labels from the wires and slip coloured sleeving over the wires.
To illustrate what I meanI've attached a few pics of an EBL1 side-contact valve being converted into an EBL31 by substituting an octal base. This is all irrelevant in your present case as all you are intending to do is to remove the bottle, snip off wires (unless you intend to keep the heaters connected for appearance sake, if intact), and to fit silicon rectifiers internally in the valve base across the appropriate pins, so you don't need to know which wire was which, and the heater wires can be identified come what may, if the heater is still intact.
You certainly like multiple challenges Nick!
Good luck with it.
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
