Noise level on WB receiver

  • Using Scan&Tioune as of today I recognized a strange background noise on my WB receiver, when doing a very wide scan. I allways was disapointed because of low MER readings. What could be the reason for this strange periodic noise? I am using a 85cm offset dish pointing to QO-100 and I have a second LNB on the side for Astra in 18 degrees.