The UHF Sonobuoy Command Transmitter (CH124B) provides only one-way transmissions initiated from the AN/UYS-503 to command activated sonobuoys. It is identical to the UHF transmitter/receiver, except that it is not configured to receive or to voice transmit. It utilizes only the lower UHF antenna.

Electrical power is supplied through the DC primary BUS at 28 VDC and the circuit-breaker is located on the HELTAS power distribution panel.