I'm doing an analysis / simulation of a tube Hartley oscillator, shown below. (full circuit from Sept. 92 issue of QST, also in _QRP_Power_) My problem is that I don't know how to treat the coil, mathematically. I asked some of my professors, but they couldn't give a satisfactory answer. I was rereading some of my textbooks and found in the derivation of the usual formula for inductance that we need to assume the wire was uniformly wrapped about the core. Also, that only assumes a single uniform current flow in the core, whereas my circuit has taps that act as current sources... Finally, I am not even sure that the same value of L should be used for all three secions of the coil! Any help would be greatly appreciated.

Regards, Ross Tucker (NS7F) Arizona State Univ, Physics dept.

circuit schematic: (use mono font) +---|(----+ | | IN --)|--+------+--/\\/\\/--+-- -- -- -- | Ct Rg ________ +---|(--+ | | _|__ | || (_ * / / */ | Lt || (_ Cf | || (_/---|(--+ | || (_ | | || (_/-------)-----------+ || (_ | | _|__ | * / / */ | _|__ * / / */

coil details: toroidal core, unknown type total 19 turns middle (Cf) tap at turns above ground bottom (cathode) tap at 1 turn above ground coils cover ~300deg of circle on core Wound on a