http://www.vk2zay.net/article/195 i think you will find that one works better. the page also gives details on things to try if it doesn't seem to work right. one detail left out is the antenna connects to the emitter of the BF199
in the circuit linked by the OP, the inductance, dimensions, number of turns, or other important details are not given. but it's easy to figure out.
given the 22pf tuning cap and 100Mhz as the center of the band, ...
1) the cap will be about 12-15pf at center tuned position
2) center of the band is 100Mhz
3) find the inductance that resonates with 15pf at 100Mhz
4) result is 150nH .... went to an inductance calculator page and entered the following, coil diameter =8mm (about correct if you wind the coil on a #2 pencil ), number of turns=5, length of coil = 12mm, wire diameter 0.5mm (page script changed it to 0.55), and design frequency 100Mhz. these figures got the coil almost correct for inductance at 125nH. if you squeeze the windings a little closer together you will get 150nH or add one more turn and stretch them out a little...
both circuits are regenerative or superregenerative receivers.
both of these receivers normally work as AM receivers, but for FM the radio is slightly off-center tuned, and the FM signal is demodulated by "slope detection".
NOTE: the antenna is connected directly to an oscillator operating at the receive frequency. this type of receiver can generate interference that radiates from the antenna.