As stated above,I have tried this on several frequencies with intermod problems and it has not worked once for me
And that wouldn't work for intermod, since intermod is almost always a legitimate (to the scanner) on-frequency signal. It's probably the most difficult problem in the industry. (And it takes the people running the systems [it's usually caused by 2 or more signals] causing it to eliminate it - there's nothing you can do as a hobbyist to fix the problem.)This would require some type of filter or antenna change.