Wood and Douglas 1335, Operating Instructions Manual

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1892 1335 - Orion Radio Modem Operating Instructions - v2.9 / Aug 2009
Earthing and Equipment Protection
It is important that the unit be correctly earthed. Failure to do so makes it vulnerable to
damage, especially where high-voltage equipment or voltage spikes are present.
These points should be earthed to a common ground point:
v The power supply negative output. Floating output power supplies are not
suitable.
v The cable screens of data cables, which should be linked to pin 5
v Equipment connected to telemetry inputs and outputs (RTUs)
v The antenna screen (where an antenna is not mounted directly on the unit)
v The equipment chassis
In installations prone to lightning strikes, a lightning arrester should be fitted where the antenna
downlead enters the building.
The chassis may be earthed via a mounting bolt provided steps (for example, a toothed
washer) are taken to ensure a good contact.
Cable grounds should be at earth potential before being connected to the unit. This will avoid
possible damage to the unit or sparks which might be a hazard in some environments.
Power should be connected last, and we recommend that you check the polarity (inner
conductor positive) and voltage (9 to 15V DC) before making the connection.