Thank you for that information. I still don't understand why one site would have many transmitters TXing on the same frequency. Sounds like I need to read up on Phase 2 systems. I think the subject I need to look up is "TDMA" or some such.
On the DB page for the system you are after, click on the Site Name of the site you think you can receive.
Then on that page, click the FCC callsign. That should open a page with a map with numbered pincushions that show the near exact locations of the transmitters for the site.
If you would only get signal from just One of those transmitter sites, the TRX-1 may work but chances are that you will get signals from two or more transmit towers for your site which is what causes the timing problems for most scanners.
You usually have a better chance if you live outside of the intended coverage area for a simulcast site as that will sometimes have a better chance in you only getting a signal from one tower in the sites mix.
If you do try a TRX-1 or 2, buy it from a place with a good return policy if it does not work. For some users, they work well but it all depends on your location in relation to the towers for a given site and if you can capture the signal from just one transmit tower in that site.
The design of the SDS models from Uniden almost guarantee they will work as long as you have a useable signal strength.