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Re: Here is schematic for 26 I'm building.

Posted by Thomas Mayer on May 9, 2007 at 02:32:17:
Hi!
nice simple design. What is the input level you expect the 26's grid will see ? Nominal CD level would drive the grid positive already.
If you stick with this op point, may I suggest to give 'filament bias' a try ? Connect the filament supply to one filament pin and the other filament pin to ground through a 1.5 Ohm resistor. This will give you the same grid bias without the need to resort to a battery. However in this arrangement the filament supply must be very quiet. I'd recommend a cutrrent source, or better yet a choke. Make it LCL, if you have the iron available.
Best regars
Thomas