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3.2 DC INPUT AND DC AUXILIARY OUTPUT
DC input and DC auxiliary output are simply interconnected inside
the unit. The purpose of this is to enable other equipment to be
connected in a DC "daisy chain" and share the same power supply.
The DC connectors have a current rating of 5000 mA, therefore if the
external power supply can deliver 5000 mA and transmitter
consumes 600 mA, this leaves 4400 mA of power available for other
equipment using the DC AUX OUT. The DC input connectors are 5.5
mm outer diameter and 2.1 mm inner diameter in the centre pin. The
centre pin is positive and the outside is negative or ground. The unit
has protection for incorrect polarity. In traditional power supplies with
heavy transformers particular attention should be paid to the to the
rectifier diodes. Usually there are 2 or 4, soldering a ceramic disc
capacitor of 1nF directly across each one eliminates all kinds of
problems with ‘humming and buzzing’. CE marked power supplies
are usually radio frequency suppressed and do not suffer any
problems.
To comply with the Low Voltage Directive and provide safe operation
the external power supply must be current limited or fused to no
more than 5 amps. This will prevent the connectors and cables from
melting in a fault condition. We recommend that 5 amp red and black
figure of 8 cable is used for wiring DC.
To comply with EMC
Directive this cable should NOT be more than 3 metres length.
