Nothing has been heard on Polk County VHF fire and sheriff frequencies since last evening. Confirmed absence of traffic using two different scanners, both of which are receiving VHF traffic from adjacent counties with flying colors. First checked thoroughly for change of DCS codes. In a long shot, checked TACN, specifically Oswald Dome and North Bradley sites, for new talk groups. Nothing found. My theory is repeater failure, or possibly switch to an SMR. I'm pretty sure I would have heard talk of the latter.