Dial Lamp Puzzle.

[pwdrive]

So to recap, pk = rms x 1.414, rms = pk x .707, pk to pk = rms x 1.414 x 2

For diode dropper calc, Vout = Vin x .707 then use this product to calculate the value of any additional series resistance required to drop the voltage down to the required total heater supply voltage at the required heater current (have neglected any forward voltage drop by the diode)
Is this correct?

Yes Lawrence, I believe that is all correct.

Regards

Thanks Robert, diode or capacitor droppers can be a bit of a trap for the unweary, so I guess this thread has been good for the advancement of the black art of radio repair/restoration.

Lawrence.