非利浦方案1900怎么调？

我目前用的是非利浦5130方案，tranceiver 是3537，PA是BGY502（集成了天线开关）
该方案有两个射频通道，一是低频同道，一是高频通道，目前低频是900，高频是1800.
根据文档，低频也可接850，高频可接1900.
可是它更换了1900的SAW后，接收灵敏度很差，点测只有-75左右。改接受回路能调高2dB,再也调不动了。（注发射功率是正常的，没动发射回路匹配）
不知道各位老大有没有这方面的解决办法?

At first, make sure your Saw filter is OK(soldering, PCB, performance, etc..)！
  I have no idea of BGY502, but since it integrates with ASM, the ASM should be of pHEMT process coherent with PA, which generally with no dedicated Rx port for DCS/PCS. So your connection style seems to be OK.
  What I am afraid about is timing/switch of the ASM, the ASM may be switched to another port as the default configuration is tri-band; on another word, you need to make sure your FESW configuration in TAT.