User manual

Chapter Three Installation
MAN_905G_1.16 Page 30
The Yagi gain also acts on the
receiver, so adding Yagi
antennas at both ends of a link
provides a double
improvement.
Yagi antennas are directional.
That is, they have positive gain
to the front of the antenna, but
negative gain in other
directions. Hence Yagi
antennas should be installed
with the central beam
horizontal and must be pointed
exactly in the direction of
transmission to benefit from
the gain of the antenna. The
Yagi antennas may be installed
with the elements in a vertical
plane (vertically polarized) or
in a horizontal plane
(horizontally polarized). For a
two station installation, with
both modules using Yagi
antennas, horizontal
polarization is recommended.
If there are more than two stations transmitting to a common station, then the Yagi antennas
should have vertical polarization, and the common (or “central” station should have a
collinear (non-directional) antenna.
Also note that Yagi antennas normally have a drain hole on the folded element - the drain
hole should be located on the bottom of the installed antenna.
3.3 Power Supply
The 105G power supply is a switch-mode design which will accept either AC or DC supply.
The module includes an integral battery charger for a backup battery.
The module accepts supply voltages in the following ranges :
12 – 24 volts AC RMS or 9 – 30 volts DC at the “supply” terminals, or
10.8 –15 volts DC at the “battery” terminals.
The power supply should be rated at 1.5 Amps and be CSA Certified Class 2. For use in
Class 1 Div 2 explosive areas (USA/Canada), the power supply must be approved for Class 1
Div 2 use.
905U
A
ntenna installed
with drain holes
down
Coax feed looped
at connection
90
o