rrkrr wrote in message ink.net...
If the filament is good and glass isn't cracked, the fact that the
mercury has condensed does not mean the tube is bad.

Absolutely true. In fact, the presence of shiny silver mercury is one
indication the tube is still good!

What it does mean
is that the tube hasn't been operated in a long time. In this case the
filament should be operated for half an hour or an hour before applying
high voltage in order to vaporize all the mercury inside.

This should be done with the tube vertical, base down *ONLY*.

Applying high
voltage to a mercury rectifier with liquid mercury on the tube elements
can result in a spectacular sound and light show...

And then it *will* be bad.

If it is bad, don't break in a dumpster!

73 de Jim, N2EY