Apeks HP Wireless Transmitter (MH-8A)

This tank pressure wireless transmitter is compatible the Apeks DSX dive computer. Also compatible with Aqualung, Aeris, Hollis, Oceanic, Shearwater, Sherwood, and Tusa dive computers that support hoseless air integration.

The transmitter is Nitrox Ready, rated for depth up to { 500 ft | 150 m }, and has a user replaceable, non-rechargeable and widely available CR2 photo battery. Although the official specifications reference the usual EN250 requirements for accuracy of mechanical pressure gauges, you can expect the ±5% full scale accuracy typical of digital gauges. The high pressure o-ring located at the base of the transmitter is a standard size AS568-012, oxygen compatible material while the battery cap o-ring used is size AS568-016, Nitrile (Buna-N) A70. Both o-rings are widely available and under normal circumstances neither o-ring requires routine replacement. The dive computer will display a low battery warning that indicates the transmitter number when the transmitter battery needs to be replaced.

The transmitter screws in to a high-pressure (HP) port of the first stage regulator mounted on the tank to be monitored. An antenna inside the dive computer receives the signals when it is positioned within { 72 in (6 ft) |1.8 m } of the transmitter and within a zone parallel or at a 45 degree angle to the transmitter. Best reception is achieved when the dive computer and transmitter are within { 3 ft | 0.9 m } of each other. During a dive you may at times move the dive computer so that is out of the signal pattern of the transmitter, resulting in a temporary interruption of the link. The link may also be interrupted if the dive computer is within { 3 ft | 0.9 m } of a running DPV or after a strobe light flashes. The link will be restored within 4 seconds after the dive computer is reoriented, moved back into range, or the interference clears. For technical diving, Dive Gear Express recommends following the best practice of also including a standard analog SPG on the regulator as a backup.

In rare cases, the body of some first stage regulator designs will have hose ports oriented such there is not room to accept a wireless tank pressure transmitter without interfering with hose routing. The solution is to use a standoff adapter, or some divers prefer to use a short 6-inch HP hose pigtail (do not forget the required Air Spool) in place of the standoff.

Officially, the Apeks branded transmitter is supported and warranted by Apeks for use with their DSX computer, not with other brands. However, this tank pressure wireless transmitter (OEM by Pelagic Pressure Systems = FCC ID MH-8A), is also compatible with those specific models of Aqualung, Aeris, Hollis, Oceanic, Shearwater, Sherwood, and Tusa brand dive computers that also support hoseless air integration with transmitters having that same MH-8A number. It is NOT compatible with Garmin brand dive computers.