Factual Information 2015:1.9 Communications/1.9.1
This page contains an extract from MH370/01/15 Factual Information which accompanied the (first) Interim Statement released by The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 on 8th March 2015.
1.9.1 High Frequency (HF) System
This aircraft was installed with Collins HFS-900 HF System. The HF communication system on this aircraft uses two HF systems with a common HF antenna to transmit and receive radio frequency (RF) signals in the HF range.
The HF transceiver operates within the frequency range of 2,000 MHz to 29,999 MHz and one KHz channel spacing.
The Left Transfer bus sends 115V AC three-phase power to the Left HF communication. The Left HF communication transceiver supplies 115V AC single phase to the Left HF antenna coupler for operational power. It also supplies 28V DC for the key interlock function. The Right HF communication system is the same as the Left, except that it uses power from the Right AC Sec 2 bus.
Source: Malaysian ICAO Annex 13 Safety Investigation Team for MH370, 8 March 2015, Factual Information MH370/01/15
The Factual Information was updated in 2018 by the Safety Investigation Report MH370/01/2018 which added new content but did not include all of the previous data.