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Old December 25th 08, 06:46 PM posted to rec.radio.amateur.homebrew
raypsi raypsi is offline
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First recorded activity by RadioBanter: Jul 2008
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Default Directly heated tube, cathode bias

On Dec 24, 8:58 pm, 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


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