Those PGA103+ amplifiers are good at a low cost. Nooelec has one but there are many others.
You will need to attenuate the 20dB gain to be something like max 6dB at the scanner or it will overload.
It can overload even with attenuation if you are too close to strong transmitters and a weak signal can be the result of desense of the receiver in the scanner, so you might in fact need bandpass filters or notch filters and even have to attenuate the signal slightly without any kind of amplifier used. It all depends of your unique situation.
There's always a solution but can be difficult to know what route to go until you have tested and tried different ones. Generally reception will improve the smaller frequency band you allow a receiver to see, using bandpass filters. A variable RF attenuator are very helpful, start at 0dB attenuation and listen to a weak analog signal and add attenuation and see if reception improves, then the signal are already too strong and need to be filtered or attenuated.
/Ubbe
