Somebody doing radio checks in Spanish (or maybe Portuguese?) on oddball frequency 26543 kHz LSB. 26,543 26.543 MHz LSB.
Given the nearly constant activity on 26.555 MHz LSB, plus 27.455 MHz USB and of course 26.585 MHz AM (Mexican trucker frequency), chances are this is one of the 26555 LSB crowd doing radio checks, tuning up his antenna, etc.