[Heathkit] Re: 6293 tube question

[Ken Kaplan]

Ok - I don't doubt that Glen is right about the 6293 being a "tougher" 6146. What I haven't 
been able to figure out is how they (the manufacturers) did it. I examined a 6293 and a 6146 
under a 10x-30x stereo microscope and I'd swear on a stack of good matched pair gold pin 
cryogenic treated shot peened magnafluxed 6L6's that they are the same inside (at least 
what you can see through the glass). The plate metal and other visible parts are the same 
thickness and the spot welds look the same. Must be something different deeper inside. 
Guess I'll have to wait until they go bad to find out.

Anyone who uses 6146 family tubes (bet there are at least a dozen of you) should read 
Glen's article on the tube.

fyi - tubes are not pretty at 10x and worse at 30x.

btw - I was just kidding about the 6L6's (especially the shot peened part).

73 Ken kb7rgg