Hi Paul, The spectrum has higher peaks at 120 Hz steps from you wspr carrier at 1500 Hz. How those go down with the distance from the carrier tells that the AM modulation mostly contains a short amplitude change lasting say less than a few milliseconds and repeating at 120 pulses/s. There is also a smaller amplitude component at 60 pulses/s. Probable reason is full wave rectification in the mains power supply and may also be sawtooth shape due to insufficient DC filtering, perhaps too small capacitance. If you have an RF amplifier that is working at saturated power, then the ripple in the DC voltage directly modulates the RF amplitude. As proposed you could try some battery as the power source to see whether those sidebands are removed. If you try FT8 mode, then your sidebands will have the same 50 Hz width as the main signal. 73, Reino OH3mA
