I built this Hartley oscillator (taken from the November 1990 edition of Popular Electronics) as part of an AM modulated signal generator project. But, it steadfastly refused to oscillate.
I was careful about layout and built it on copper clad board, triple checking all connections and component values. I even clocked the confusing reversal of drain and source. Still nothing.
So, I modeled it in LTSpice and it doesn't oscillate there either, even after playing around with the values. Is there something I'm missing here? I'd still like to get this oscillating, since I've put some effort into its construction.
For parts I used an air blade variable cap (10 - 317pF) and an old RF transformer that I tuned to 255uH (to give me the low end of the MW band) on the primary (the tapped coil is about 7uH). I wound a new secondary to give me the 7uH I needed according to the 707VX spec (which has a 6:1 turns ratio).