I'm staying in the Phoenix area for the week. First thing I find on a search with my 996 is a p25 trs with a SID of 015Ah-0123 and a cc on 774.34375. Unless I missed something, it's not in the RRDB. Sounds like fire ops on TG 1104. Who is it?
Also FYI, 774.34375 is part of the State Licenses block of the 700 MHz spectrum, which is why you won't find it on any FCC licenses. It falls under Arizona's WPTZ765 statewide license. States are not required to license sites individually, nor do the SL licenses specify specific usage or sites.
I was talking about searches on the FCC ULS, not RRDB. If you tried to search for 774.34375 in Arizona on the FCC's site, you would've come up empty because the state is not required to license the frequencies/sites individually that are already covered under their statewide SL license.
When searching for System ID 15A on the RRDB, the Yuma system pops right up. You probably tried to search it by using the leading 0 or trailing h that your scanner displays.
Searching 774.34375 in Arizona on the RRDB Frequency Search by State returns the Yuma system as the only search result. A Trunked Frequency Search of Project 25 with that frequency also returns the Yuma system in the search results.
I'm surprised you had trouble finding it using the RRDB searches.
Talkgroup 1104 on the YRCS has not been identified yet. This talkgroup is ADOT, but not sure of the channel number or channel name. If you are able to positively ID the channel, please submit to the DB.