I just got my hands on some nice 50's Sylvania 1n34a's. They are the heavy duty type glass case with the thick leads tapering down to normal thickness wires. They all have some kind of loose white powder in them. It looks almost like aluminum oxide or some other fine oxide powder.
Is this some getter type meterial they phased out later?

There should not be anything loose inside them.

Dave

Some old diodes did have a white powder inside. Believe it was there as a drying agent.

That is interesting, I have never seen one with a powder inside. All of my Sylvanias from the 50's are clear.

Dave

Hi Dave

We don't think of diodes as having white powder inside. It can easily be seen on early RCA diodes which are clear glass and have metal ends. Look inside the glass while moving the diode around. You will see the powder move.

Old diodes with white powder inside look somewhat like this:

http://www.ebay.com/itm/Diode-Germanium ... 45ecd1d999

http://www.ebay.com/itm/5-1950-Point-Co ... 4ab39e6053