Re: Tube Coil
> Do I use RF chokes on the Sec. lines of the xformer on a tube coil.
RF chokes are not necessary unless the tube coil is run in a pulsed mode.
>Do I rectify the output and feed the system with DC or does the tube preform
The tube will automatically rectify the AC.
>Is the pri/sec a normal Tesla setup driven by the tube arrangement.
Yes basically, but the primary will probably require about 22 to 32 turns for
proper impedance matching to the tube, depending on parameters such as tube
type, voltage, power input, etc. If the primary has too few turns for what
the coil needs, the tube will overheat. Also, tube coils especially small
ones, usually use a cylindrical primary, but you can use a saucer primary.
If the tube plate runs too hot (too red), you can do any or all of the
following; reduce the coupling, increase the grid leak resistance, decrease
the grid leak capacitance, add more primary turns (and of course use a
smaller cap to stay in tune), reduce the number of grid coil turns (or move
the grid coil farther from the primary), vary (optimize) your tuning. There
will be a tuning range where the coil will give the same spark length, but
towards either edges of the range, the tube will run cooler, spark will be a
little dimmer, but just as long, that's the most "efficient" tune-point.
> Im thinking of using an 811-a in a "Hartly Oscillator" design. It appears
>that the pri. in the tank is center tapped to ground.
I never tried the Hartley circuit.
>Im going to try a microwave transformer, and buy a filament transformer
depending >on the voltage of the 811-A , I think its 10v but Ill find out for
Microwave trans will work for up to a 10" (maybe 12") spark. Filament
voltage for the 811A is 6.3 volts, this is convenient, since you can use the
transformer from an old junked TV chassis if you want to limit the cost.
Hope this is helpful. Happy and raspy tube coil sparks!