Tvheadend

Hi,

I'm trying to use tvheadend with the Swiss Cable network (dvb-t). I've got 1 tuner in my pc ( Philips TDA-10023 DVB-C).
I used professional cables but unfortunately I'm not able to get a good signal quality.
When I restart tvheadend and attach the antenna I got 100% signal quality almost everywhere. I can watch tv and anything works fine.
But after some minutes the signal quality start to decrease and all mulitplexes get to 0% signal quality.
I am sure the signal quality should be quiet good.

I deactivate the monitor signal quality, but that don't help.

Any ideas?

thanks,
Mario