I tried to help by looking up rsw434 but got rws 434. data sheet shows the tx and rx to be small modules with no access to on board connections. It is conceivable that the input overloads when the tx is close. The output power of tsw 434 is 16 dBm which is 40 milliwatt.
So, I'm not sure what youve got or whats happening cos yr description doesnt fit the facts I have.
I got a data sheet from wenshing and it refers to AGC but doesnt say the AGC function can be accessed. Not sure about your '+ input' and '- input'.