Broadcast PLL - Veronica NRG 2025

[BriansBrain]

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

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

Veronica NRG 2025 - Siglent 29-08-2025.jpg

Thanks a lot for yours and everybody's help

.

[reverend]

No need to replace C31 then...!