Transmitter section of a weather radiosonde from late '90s. the circuit uses a crystal oscillator along with a 4046 PLL and a prescaler. the tx frequency is around 403MHz, tunable. There is a trimmer for adjusting the right side varicap in the xtal oscillator; the 2 varicaps on the left, in a back to back configuration, are controlled by the 4046 PLL;  the bottom trimming cap is for the tuning of the output stage.

the measured output power was less than 2 mW. Well constructed and very stable.