So, yes it is the season, one ideas was to use a strip heater -yes I did not want to put that in the title, it may have sound too....
found this stuff for telescopes, works on 12v so nobody will get zapped
https://agenaastro.com/dew-not-dew-remover.html
then a controller is needed
Astro Zap dew heater controller, https://agenaastro.com/pegasus-astro-dew-zap.html
then a 12v power supply...
thank you for your ideas
My initial though was xmas lights.... but they are all led now...