Hi Radu,
I’m back online.
Thank you for your reply.
I think that I’m hitting some parameter limits of the soldered inductor or capacitors. There is a temperature related limit after which there is a big step in the duty cycle and the voltage regulation become very noisy.
Is it possible to have the exact models or parameters of the inductor and 1kv 10nf capacitors included in the kit ?
I would like to try NP0 capacitors and better rated inductor to try to get less noise an better regulation under temperature stress.
I would like to try this before pushing up the inverter frequency which could lower it yeld.

Other than this minor nit (I’m a little bit perfectionist ….), the unit is up for more than ten day now and it work beautifully.

Emmanuel.