[amsat-bb] 70cm preamp

On my V/U setup I have a SP7000 70cm preamp. Working FO29(JAS2) my 2 meter signal overloads the preamp, my signal splattering like an adjacent strong station. With preamp off the problem is not there. In testing I found the overload happens in any combination of 70cm 2m frequency pairs. I can eliminate the problem by lowering the tx power, but by doing so I have a hard time copying my own signal. How can I eliminate the 2m sig overloading the preamp while still maintaining adequate power? Antennas m2 436cp30, Gulf Alpha 2m5el, both right hand polarization. I could use some suggestions. Thanks Bill