PRCguy is right. You're overloading your receiver. If I'm not mistaken, that Ramsey preamp isn't adjustable. I recommend a preamp with a gain adjustment so you can experiment with different settings. I often tell people to use a preamp as a last ditch effort. Using a better antenna and cable comes first. Or if you use a multicoupler, a preamp is almost a must due to the loss in the coupler or filters if used.
I experimented recently with a Stridsberg multicoupler. The one with out the preamp. I had a noticable drop in signals going through the multicoupler. I added an adjustable GRE preamp and what a difference it made. It overcame the loss of the multicoupler and then some.