[R-390] One last ballast alternative - 12BH7, 12BY7

[Tom Norris]

I don't remember the 12BH7/12BY7 being mentioned in the
latest round of zombie* horse beating. I had forgotten all about it
until I popped the top on a 390A over the weekend. Seems I had
used a "bad" 12BY7 in one of my sets some years back, it still works
fine. Is cheaper than a ballast - most of the time, especially if you
have a few lying around. Filament current is 300 ma and this particular
radio has worked fine with this "fix" for 8 years or so. Drift and
stability is comparable to my other receivers that use ballasts.

Tom NU4G

*Zombie Horse Beating -- this horse has been beaten so many times
it's become undead. At least judged by the number of times this
subject comes up over the years. :-)