The ornamental design for a cablehead, as shown and described.
FIG. 1 is a top, front perspective view of a cable head, showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing the connector and cable in FIGS. 1-7 are included for the purpose of showing environmental structure and form no part of the claimed design.