This little transmitter is suitable for less demanding Doppler propagation measurements. It is designed for use on 80m, but can be easily adapted for 40m or 20m. The output is about 500mW of unmodulated carrier, with a stability of about one part in 106, or ±3Hz on 80m. With care (for example mounting the unit in a diecast box, packed in an outer box of expanded polystyrene) stability will be even better.
The transmitter consists of a TCXO (Temperature Compensated Crystal Oscillator) reference at about 14MHz, followed by two divide-by-two CMOS dividers, and a Class E FET power amplifier. Follow the Schematic Diagram as you read the description below.