Gentlemen, I am seeking advice. I have a problem with a pair of
Amperex 3-500G valves, manufactured in France. The problem is that the
wire from one side of the filament, through the glass envelope and
connected to the valve pin, had a "dry" joint connection to the pin.
The joint, being high resistance, began to heat up, and over time, got
worse, to the point that the tube heater volts dropped and the
emission dropped off, then, more heater power was dissipated in
heating up the tube pin joint, to the point where the paxolin disk,
which supports the pin, has become charred around the base of the pin.
This problem is the same on both valves for the same pin. The position
of the pin is the heater pin located at "11 oclock" (socket pin 1?) as
you view the base of the valve. I would suspect this as being
a "batch" production problem, and suspect that others may have had a
similar problem, but how to resolve the situation. I have thoroughly
cleaned both the plated brass pin and the connecting wire, which is
not copper, and reconnected the two together by means of soft solder.
I presume that the original manufacturing process was one of
automated gas jet brazing, or hard solder, and the flame to that pin
assembly was defective. Now, should I endeavour to braze or hard
solder the connection, in order to preserve the integrity of the
connection, or will my soft soldering be sufficient. I would be
grateful for advice in due course....a contact e-mail address for
Amperex in France would be especially helpful....sincerely John. G3JVC
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