I have tried again and move the dvb card to my windows machine and it works
much better, no bad reception and no channel tuning problems.
But I want it to work on linux and not windows.
Do you have one of the cards where the PWM value stored in the card's
EEPROM needs to be overridden? I don't remember exactly for which cards
this was required or improved things, maybe you want to check the mail
archives or just try to override it using the 'pwm=' module parameter
for ves1820.o and optimize this value by trial'n'error...