[R-390] Blowing B+ fuse

[Tim Shoppa]

> The B+ inrush with the silicon diode modification will be huge.

It's not so bad - the diodes don't drive filter capacitors directly, there's
big filter inductors in the way.  If a B+ fuse blows, it's not directly because
of the solid-state PS mod.  (Now it may be indirect if the extra B+ volts causes
a capacitor or tube to fail shorted)

I've made measurements of AC inrush current with and without
inrush-limiting thermistors, I'll see if I can post oscilliscope traces on the
web somehow.

Tim.