Perhaps if you could indicate which system(s) you're having issues with (hopefully with a link to the RR Database entry for them to clearly indicate which one(s) they are) folks may be able to assist. If you're listening to one of the multi-site systems (such as Ohio's MARCS), please include the tower or towers you've got programmed in and the scanner's tuned to when the problems are happening. Examples of the desired talkgroup(s) might also be helpful for trunked systems, especially those multi-site systems like MARCS.
Also providing the same info on the new antenna would also be helpful (the link this time would be to the Radio Shack site).
There are several things that may be happening, depending on what the specifics of your desired systems are. Things like:
* the salesperson sold you an 800 MHz specific antenna when you're actually trying to pick up signals outside of the designed band for that antenna.
* you're trying to listen to a simulcast system and having issues due to too strong of a signal from multiple towers in that system (yes, I said too strong of a signal even though it may look like your issue is too weak of a signal, a very common issue).
* you're having issues due to very strong very local signals overloading your scanner so the weaker signals are drown out (like hearing your car radio just fine with the windows down until that very loud chopper pulls up right next to you).
* the talkgroup you want to hear is on a multi-site wide area system and there are no users on your local tower(s) affiliated with that talkgroup (basically no local users are on that talkgroup at the time).
