[R-390] C-103

[Craig C. Heaton]

Joe,

On the tubes, the Collins engineers knew what they were doing. Wait for the
correct tube. About the only tubes on the R-390A that can be played with are
the ballast tube, which can be removed pins 2 & 7 jumpered (then the BFO&PTO
toob replaced with 12BA6's) and the two rectifier tubes can be solid stated.

Ask around and see if anyone local has a tube collection and selling at
reasonable prices. Hamfest are another source, I'm getting tubes there for
my R-390A at one buck each.

Craig,