Many (most??) of those Chinese-made POS's use 50 microsecond pre-emphasis, and modding them to 75 is all but impossible, given the micro-tech circuit board construction!! Yeah, I tried to do a pre-emphasis R-C swap on one of these things a couple of years ago --- and finally gave up!!
If you want to use FM to broadcast a church service, etc. ---- just get a Ramsey, or even a "Talking House" (newer model) and keep your audience close!!!

250 uv @ 3 meters doesn't travel far!!