When I use SSB on 20, 18 and 15m, I get a strong signal (20db below the main signal) 2.8Mhz left and right of the tx frequency, as if the carrier is being amplitude modulated with 2.8 Mhz.
I already tried disabling the PA power and measuring the signal at different points before the PA, but this signal isn't there, not even directly at the power MOSFETs. When I enable the PA, I can't measure low power signals on the PCB anymore.
On all other bands, this singnal isn't present. In CW mode, the signal isn't there on any band.
Has anyone observed something similar? I'm completely at a loss. Spectrum analyzer screenshots will follow as soon as I get everything set up again.
