[time-nuts] injection locking

[Joop]

Kit VK2LL wrote:
>Theory suggests that lock sensitivity could be improved in this instance
>if the 10MHz duty cycle was changed from 1:1 to 6 or 7:1, the idea being
>that the narrower pulse should be <0.5 period of the frequency of the
>oscillator to be locked.  

Ah, that triggers some thought.
I know from (ARDF) experiments that sub-critical oscillators can be used
as very narrow filters. Just as the Q-multiplier circuits.
Even at the point where there is enough gain and oscillation starts, I
found the oscillator tracks and locks onto the incoming frequency.

Thinking this way of injection locking, it makes sense to increase
harmonic content of the injected signal. In essence it will then not lock
onto the fundamental frequency, but on some harmonic part of it. In my
SPICE investigation I injected a clean sine signal. Perhaps I should try
with some clipped or digital signal.
That might also explain why James G1PVZ was so successful. The bottom
2N918 might cause a lot of harmonics if driven into the collector cut-off.

Joop PE1CQP