EDIT: I stand corrected. McMinnville does have a trunked system for police / fire / EMS. I didn't see WPYJ327 in the DB until just a few minutes ago.
Digging around in FCC ULS, I see Yamhill County has a 800 MHz license.
Could that be it?
I did some research on that, and found this article:
That 800MHz system is either currently a link between McMinnville and Newberg, or will be soon. That's just a guess.
Finally, there was this note before the link for the MPT-1327 system disappeared from the DB:
Latest News Update Posted on 2008-04-21 19:05:22
The YCOM MPT-1327 System has been deactivated effective 4-16-08. YCOM has switched to a conventional system using the formerly trunked frequencies.
Emphasis mine. I can confirm this, too. 460.275 and 460.4125 of the former Site 3 in Newberg had police traffic a few nights ago. Nothing big, mind you, but it was there. The other frequencies I'm not sure about only because I never had them programmed into my scanner.
In case you didn't write them down, here they are:
Former Site 1 (McMinnVille)
Former Site 2 (Sheridan)
Former Site 3 (Newberg)
A final note: I've only been scanning for seven months now with a BC92XLT, so I'm not stating any of this information as "accurate" unless others come to the same or similar conclusions. I don't want anybody thinking I know what I'm talking about when I personally don't have a clue...