[R-390] building new components (PTO)

[Conard Murray]

Back when I was a young whippersnapper, my elmer was given a '390A from
a batch that MARS was distributing without PTOs. This guy was a
build-it-yourself sort of ham and since PTOs weren't as available in
1978 as they are now, he built up a solid state VFO for it using a 10
turn pot as the tuning element. 
I especially remember this because we went through what seemed like
thousands of 10 turn pots at hamfests looking for a non-wirewound one
for the tuning element. 
This lashup actually worked out with fairly decent tracking, so it can
be done. 
Conard, WS4S