The D/70/H is a standard D/70 hydrophone element combined with a signal conditioning amplifier.

The pre-amplifier is housed in either a stainless steel or nylon tube with an O ring sealed lid at each end.
The hydrophone element is moulded in polyurethane onto one of the lids whilst the other acts as a penetrator for the multi-core screened cable. Two of the cores are used for supplying the 24 volt power with the other pair providing the differential output signal.

The proximity of the amplifier to the D/70 hydrophone allows the signals to be transmitted along long lengths of cable (up to 150 metres) without suffering any degradation. The differential output also improves the signal to noise ratio and extends the upper frequency cut-off. The gain of the amplifier may be adjusted using links provided on the PCB.

Available without pre-amplifier allowing customers to use the housing for their own electronics. This option is also useful for other special applications e.g. the device could be used as a projector with the tuning and matching components fitted into the housing.