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The table which follows, shows the approximate losses that will occur when using various lengths and
types of coaxial cable in 200 MHz band. Regardless of the type used, the cable should be kept as short
as possible to minimize signal loss.
Cable Type
RG-8A/U
1/2-inch HELIAX
7/8-inch HELIAX
1-1/4-inch HELIAX
1-5/8-inch HELIAX
3.4
Power
The transceiver may be operated from any well-filtered 10 to 16 VDC Power source; 13.8 VDC Nominal.
The supply must be capable of providing up to 7 Amps maximum, and 2.5 Amp consistently. With each
radio, an 03-1846A02 cable (as shown in Figure 6 below) is shipped, providing the matching power
connector on a 3-foot power cable. Ensure to tighten the connector securely to the radio. A surge
protection device such as a Transtector 1101-624 should be employed.
NOTE
The radio is designed for use in negative ground systems only.
Consult the following table to determine how much current is required for receiving or transmitting vs.
input voltage and RF power output. Duty cycle is a function of how many time slots of the 8 per second
are used for transmission. The STFP protocol used by the communications manager to send data into the
radio for transmission over the air specifies what time slot to use for each. If the communications manager
uses all 8 slots, the duty cycle is 100%. If four are used every second, the duty cycle is 50%. If 7 are used
every 3 seconds (24 slots), the duty cycle is 29% (roughly 30%). Many other duty cycles are possible
depending on the epoch size and number of transmissions within each epoch. All MPE RF safety
calculations are based on the highest ERP levels.
6
Table 2. Signal Loss in Coaxial Cables (at 200 MHz)
10 Feet
(3 Meters)
0.26 dB
0.06 dB
0.04 dB
0.03 dB
0.025 dB
Figure 6. DC Power Cable (P/N 03-1846A02)
TD220MAX Technical Manual
50 Feet
100 Feet
(15 Meters)
(30.5 Meters)
1.27 dB
2.50 dB
0.38 dB
0.76 dB
0.21 dB
0.42 dB
0.16 dB
0.31 dB
0.13 dB
0.26 dB
200 Feet
(61 Meters)
5.07 dB
1.60 dB
0.83 dB
0.62 dB
0.52 dB
MDS 05-6906A01, Rev R
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