User's Manual

MDS 05-4121A01, Rev. 02 TRM SB Integration Guide 15
At remote sites, a directional Yagi (Figure 7) or corner reflector antenna
is generally recommended to minimize interference to and from other
users.
Invisible place holder
Figure 7. Typical Yagi Antenna for Remote Sites
Feedlines
The selection of antenna feedline is very important. Poor quality cables
should be avoided as they result in power losses that may reduce the
range and reliability of the radio system.
Table 3 shows the losses that occur when using various lengths and
types of cable at 400 MHz. Regardless of the type of cable used, it
should be kept as short as possible to minimize signal loss.
2.4 Primary Power (3.3 Vdc)
DC Supply Connection
The transceiver can be operated from any well-filtered 3.3 Vdc power
source through the
DATA INTERFACE connector. The power supply must
be capable of providing at least 1.5 Amperes and provide current
limiting even if you intend to operate the radio at low power (0.5 Watts).
NOTE: The radio is designed for use in negative ground systems only.
There is no fuse or reverse polarity protection provided on the
transceiver’s PCB assembly.
Table 3. Length vs. Loss in Coaxial Cables at 400 MHz
Cable Type
10 Feet
(3.05 Meters)
50 Feet
(15.24 Meters)
100 Feet
(30.48 Meters)
500 Feet
(152.4 Meters)
RG-8A/U 0.51dB 2.53 dB 5.07 dB 25.35 dB
1/2 inch HELIAX
0.12 dB 0.76 dB 1.51 dB 7.55 dB
7/8 inch HELIAX
0.08 dB 0.42 dB 0.83 dB 4.15 dB
1-1/4 inch HELIAX
0.06 dB 0.31 dB 0.62 dB 3.10 dB
1-5/8 inch HELIAX
0.05 dB 0.26 dB 0.52 dB 2.60 dB
CAUTION
POSSIBLE
EQUIPMENT
DAMAGE