Fellow RCMers,

I've been reading a book from the 50's that describes different kinds
of electrical motors and how to repair/rebuild them. In one part, it
very briefly recommends using a "growler" to test an armature.
Unfortunately, the reference was short and pretty obscure, and I was
left in the dark as to what the test would even accomplish. Does
anyone know the answers to any of these questions?:
1) What does a growler measure?
2) How to you correctly use one?
3) Can you build your own?
4) Has it been replaced by a newer device? I notice that neither HP
or Fluke offer one, so I suspect it may be antiquated.

This question might be better suited for rec.electronics or something,
but I know the metalworking hobby tends to generate piles of broken
motors (got a few myself) so I thought I'd check with y'all first.

Thanks!
Dave Doerschuk