[BC] tube sound (tube transmitters)

[nakayle@gmail.com]

  Well in defense of "old Bessies" everywhere, tube transmitters will shrug
off voltage spikes that can wipe out dozens of sold-state modules.  A
station I'm familiar with here in lightning country got hit at least once
every summer.  They ran a hybrid transmitter with solid state exciter,
driver and control logic- and tube finals.  Every hit would zapped one or
more solid state components but the old tubes would fire up and go right
back to work.

 -Nat kayle