The license for this system, WQDN876, shows two control points (one at Webb Cty SO and one at Webb Cty Road and Bridge Dept.).
The control station will input on 153.7625, 153.980, 154.725 and 155.1525.
The transmitter will broadcast on 155.730, 155.8275, 155.910 and 159.030.
I find it interesting they only have one transmitter site, it's south of Laredo in La Presa (27 23 56.7 N, 99 26 02.3 W). This is probably why you're receiving it so well troubadour- it's practically in Laredo.