The problem could be that your Linear LNBF is not aligned correctly to the satellite. Since the switch degrades the signal a little, it becomes obviouse that the signal reaching the receiver is not strong enough.
I may recommend the following:
1- Make sure your LNBF is aligned perfectly. What is the receiver you are using, and what signal quality are you seeing without the switch?
2- Check the
coaxial cable/connectors you have between the LNBF and switch. Use high quality cable/connectors only.
3- You may want to consider adding an inline amplifier between the LNBF and switch.
4- If all else fail, try changing your switch and see if the signal improves.
Best of luck.
=D>