Tim Wescott wrote:
Bill M wrote:
I'm a little confused again.

Setting up a 1624 tube for cathode biasing and also need to create a
center tap for keying to ground.

The book says 610 ohms at my voltage. So would I use a pair of 1200
ohm resistors in this case?

My logic is since there is not a separate cathode then the two R in
parallel would raise the filament 'cathode' 600 ohms above B-minus.

TIA and Merry Christmas,

Bill

(Disclaimer -- I haven't done this. It's just knowledge gotten from
lots of books, and lots of solid-state circuit design experience).

No, because all the filament voltage will go to mildly heating up the
resistors, and none will go to wildly heating up the filament.

Use a center-tapped filament transformer, and put the 600 ohm resistor
between its center tap and ground. If necessary, use a separate
transformer just for the 1624s.

If his un-centertapped filament winding is ONLY supplying that one tube
and he has each leg going to ground through a 1200 ohm resistor that
would result in a 600 ohm connection to ground. So it should work.
Remember that's 2400 ohms across the filament, it won't suck up much
heater current at all.