I am also fairly new to the list, but I am using the DVB-T e4k dongle that you use. I was under the impression that e4k has a range up to 2.2 Mhz, and yet you are feeding it 100 Mhz. I am surprised it even tunes in! I don't think it is meant to work that high :-(
Up to 2.2 GHz ... not MHz ... you're off by a 1000x factor.
Cheers,
Sylvain