Installation manual

Transceiver Unit Connecting Power
16 Apr 2004
4
4.2.1 Ship Source Impedance
It is required that the total source impedance at the
Transceiver Unit does not exceed 250 mΩ.
Select a power outlet from the 24 VDC ship supply, and
measure the source impedance of the ship installation as
described in appendix C.2.
If 50 mΩ ship source impedance is measured, only 200 mΩ
is left for power cable loop resistance (250 mΩ - 50 mΩ =
200 mΩ).
If the total source impedance is too high the voltage drop
when the terminal turns on, is so large that the terminal
turns off again. When it turns off the voltage drop goes
down to zero and the terminal turns on again, and
therefore the terminal rapidly turns on and off.
The cable inductance should not exceed 5µH
. If the
inductance is too high, the Transceiver Unit Power Supply
may start to oscillate. You will hear an oscillating noise
from the power supply and the antenna voltage will be
insufficient.
4.2.2 Power Cable Selection
In order to make sure that the power cable fits the power
connector the dimensions of the cable must be:
• Cable outer diameter max 3 mm
• Inner core 1.5 mm
2
To minimize the cable inductance a multi 2- or 4-wire cable
should be used.
Recommended power cable types and length from source: