[R-390] Megacycle detents, nominal B+, and bad tube brands

[Tim Shoppa]

The megacycle detent on my 390A seems not as tight as it should be.
Especially tuning around bands with a "cusp" (e.g. middle of 15MHz)
in the cams the Megacycle knob will occasionally twist out of the
detent as I tune the kilocycle knob around.  Is it a good or a bad
idea to bend the megacycle detent spring a little bit to help out?
Or any ideas for a more permanent solution?

My 390A has had its power supply solid-stated, and a 100 Ohm dropping
resistor put in.  The B+ I measure (audio B+) is 227V in AGC or MGC and
252V in Stand-By.  This is with 120VAC power in.  This seems to me to
be on the high side, although I don't know what the official number is
supposed to be.  There's real nicely regulated 150V on the regulated
supply.  To lower the non-regulated B+, is the answer more dropping
resistance (200? 250? Ohms?), a 40V 10W Zener, a bucking transformer, ???

Oh, I ordered some 12BA6's to eliminate the ballast tube issue.

And on bad tube brands: "JJ" (Eastern European manuf) ECC82's/12AU7's
are not too good in the 5814A spots.  I've had two develop filament-to-
other-element leakage that gave intermittent hum, just in the past week.
Luckily I have a good supply of JAN 5814A's.

Tim.