Puzzled, basic flyback converter

[skenn_ie]

Hi. Can anyone shed light on this trace ? A very basic flyback converter, channel 2 is the mosFET drain voltage, channel 1 is the transformer output.
rectifier with 4ohm loadWhy am i seeing ringing on the output during the ON phase of the primary ?. If I short the (schottky) diode, the ringing stops.
TIA

 

[bertus]

Hello,

Can you post a complete schematic?
That way we can see what you are trying to do.

Bertus