14 Mar
2013
14 Mar
'13
2:33 p.m.
Also though you can peer thru the glass at the insides
some of them can
be hard to figure out the number of in 40 or 60 years of storage, so
make sure that you keep them such that their legends don't get rubbed
off in storage. Some of them will have the numbers applied to the glass
via some process that really is indelible short of breaking the glass,
and I've seen some with some sort of white ink that didn't last the
lifetime of the tube (was messed up when I took it out in the 60's)
Luckily in some cases you can read the chassis to determine the numbers.
There was a rumour doing the rounts about 50 years ago that at least one
manufacturer used water-soluble markings on the valves. The idea was that
old valves could not be washed and cleaned up and then sold as new ones.
Certianly soem markigns do come off very easily.
-tony