[ARC5] Tube Substitution

[Robert Eleazer]

I have been fascinated by the 12SK7 - 12SH7 discussion, partly because that is the kind of stuff I like to try.

In regards to the more general subject of tube substitution, does anyone know of a chart that shows the 7 and 9 pin miniature tube equivalents for the 8 pin octals and loctals?  

I once had a need to test some 5670's, and the problem was that the local Lafayette store tube tester (within easy walking distance of my apartment) lacked that tube on the chart.  After consulting the ARRL handbook, I was able to find a tube type that was similar to the 5670, with a different pin out and made an adapter (think it was one of the 12A*7 series), using one of those old "turret sockets."  I tried it out in the Lafayette store and it worked; the clerks there eyed me suspiciously when I pulled that contraption out but let me use it.  Of course, this was circa 1981 and they probably would not have noticed if the tube tester had vaporized anyway.

Wayne