Re: Directly heated tube, cathode bias

raypsi wrote:
On Dec 25, 12:46 pm, raypsi <RBorow...@xxxxxxxxx> wrote:
On Dec 24, 8:58 pm, Bill M <radioex...@xxxxxxxxxxx> 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
hey OM:

Exactly and you will need at least 10 watts of resistors to be safe.
Because they also will have to handle plate, grid1, grid2, and the
current they draw across the filament. I suppose if they where wire
wound like 25 watt you could stick a ferrite rod in their hole and
make them your filament chokes also. But if you use carbon comp
resistors then part of your drive will go heating those resistors, so
not much gain going on there.

73 OM
n8zu

Well they ain't filament chokes, but in the drive circuit the drive
signal won't go to heating them up if they are chokes. So they will
only be taking about 1 mil of current from the filament circuit.

73
n8zu
One possible problem. If this is an RF amplifier circuit you probably want to use NON-INDUCTIVE resistors in the circuit or they WILL act as chokes!
.

Relevant Pages

  • Re: Directly heated tube, cathode bias
    ... Setting up a 1624 tube for cathode biasing and also need to create a ... parallel would raise the filament 'cathode' 600 ohms above B-minus. ... Exactly and you will need at least 10 watts of resistors to be safe. ... but in the drive circuit the drive ...
    (rec.radio.amateur.homebrew)
  • Re: Directly heated tube, cathode bias
    ... Setting up a 1624 tube for cathode biasing and also need to create a ... parallel would raise the filament 'cathode' 600 ohms above B-minus. ... Exactly and you will need at least 10 watts of resistors to be safe. ... but in the drive circuit the drive ...
    (rec.radio.amateur.homebrew)
  • Re: Directly heated tube, cathode bias
    ... 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. ... If the filament winding isn't center tapped, then two resistors form the center tap. ...
    (rec.radio.amateur.homebrew)
  • Re: Directly heated tube, cathode bias
    ... Setting up a 1624 tube for cathode biasing and also need to create a ... The book says 610 ohms at my voltage. ... parallel would raise the filament 'cathode' 600 ohms above B-minus. ... Exactly and you will need at least 10 watts of resistors to be safe. ...
    (rec.radio.amateur.homebrew)
  • Re: Directly heated tube, cathode bias
    ... Setting up a 1624 tube for cathode biasing and also need to create a ... parallel would raise the filament 'cathode' 600 ohms above B-minus. ... Exactly and you will need at least 10 watts of resistors to be safe. ... but in the drive circuit the drive ...
    (rec.radio.amateur.homebrew)
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