IF transformer coupling continued

You can see the output swing as the coupling increases.

The frequency shift because the loading draws inductance from the primary. I can not help but wonder how many times a well built regen failed to function simple because the coils were over coupled. I mean more is better does not away apply. The early builder would go to great lengths to make their coil adjustable for this very reason. 

If you examined the previous post you should have observed over coupling reduces output in an IF transformer.