I use a Hamtronics amp on my base 800 antenna and it does a great job in pulling in 800 signals. However I am in the country, buried in the woods with high trees and high house so I don't worry about front end overload. But, as Statevillan said I think in most cases an amp will overload the front end of the PSR500. I too used the GRE amp on my Pro96 but have not used it on the PSR500 in a mobile environment. I play with the squelch and ATT to improve reception in a mobile mode.