[Elecraft] Kester Resin Five 50/50 alloy solder

[Nancy and Bob Widmaier]

Can anyone tell me what Kester Resin Five 50/50 alloy solder is made of.  I have an old roll since when I was a kid ham radio buider.  

Is it a rosin core solder? Is it acceptable for soldering PL259 connectors and such?

Thanks and 73,

Bob Widmaier
K3JOP