I found out what the reason was for the bad carrier suppression at 20 meter. The problem is the sideband oscillator. I did not have the xtal for usb. so I have use a 27 MHz on its fundamental frequency of 9 MHz. I had to make provisions to tune it to the right frequency. That worked but the signal shape is not a nice sine wave. This causes bad suppression of the carrier.
I will make an separate sideband oscillator with some filtering. That should fix the problem.
I have made an enclosure for the radiomyself. Using some laminated wooden furniture plate and some PCB plates. A picture will follow soon.
A metal case would look better but I don't want to spend too much money on this radio . However it is retro style. That suits the radio fine.
I will make a separate box with a PLL synthesizer to improve the stability. The PLL is working. It was leftover from another project. I need to make a controller for it using a microcontroller.
