reverend wrote: ↑Tue Aug 26, 2025 2:24 pm What is the control voltage feeding the VCO varicaps (measured at point P3). If this is too low (below around 3 or 4 Volts) the varicaps may be being driven into saturation and that will cause a large leap in all sorts of nasty products.

Adjusted to a perfect 3.2V now, it only dropped the 50HMz by about 0.5dB
So that was not the problem.

But

reverend wrote: ↑Tue Aug 26, 2025 2:24 pm Also the matching into the gate of the RD15 doesn't look optimal. You could try removing the 2u2 inductor and replacing it with L4, then making L4 a short circuit. You may also need to lower C31 to 33pF or less to provide a proper match.

Done... 2u2 replaced with L4.
L4 = Short.
Before I replace C31 this is the result Thanks a lot for yours and everybody's help

.

No need to replace C31 then...!