When I received it, it would only do 900 or so watts PEP and was flat topping.
It is supposed to do at least 1400 watts PEP.
Looks like the 500 volt rated silver mica caps in the 80 meter output filter can't take that kind of power if the audio is too hot or the SWR is too high.
Sorry to read of your troubles. I gather from others and my own experimenting with this TX that it should be limited to 200-225 watts carrier. Also the TX must only see 50 ohms. Dont push the limits on this TX. There is no metering so you have no idea of drain currents on those finals (unless a newer model has this feature).
When operated in a safe range the DYY TX does pretty well.
My .02...worth just that perhaps....
Peter