Two versions of a vf transceiver to aid in locating trapped miners were developed and tested. A belt-worn model was produced in both transmitter and transceiver forms. In addition, a quantity of the belt-worn models were fabricated using aluminum wire instead of copper to reduce unit weight. Ten prototypes of a battery cap model vf transceiver were also fabricated demonstrating further unit size and weight reduction while maintaining electrical performance. Although both versions of the vf transceiver are similar electrically, and both are constructed using conventional manufacturing techniques, the battery cap model realizes a lower total weight, smaller volume, and lower production cost than the belt-worn version. Samples of both versions were tested environmentally, and the test data are included in this report.