Racal Instruments AN/TRC-207, Operation And Maintenance Instructions, Page: 51 / 102

TO 31R2-2TRC207-1
5-3
5-2.9 Antenna System
The antenna for the bi-directional repeater provides simultaneous transmit and receive capability. The antenna provides
transmit and receive frequency coverage over one of each of the bands of operation. Three antennas cover all of the
frequency bands of operation: 30-88 MHz, 136-174 MHz, and 403-470 MHz.
The antenna provides an average gain in each band as indicated in Table 5-1.
Table 5-1. Antenna System Frequency Band Vs Gain
Frequency Band Gain
30-88 MHz -7 dBi to +2 dBi
136-174 MHz +2.5 dBi or greater
403-470 MHz +2.5 dBi or greater
5-2.10 Diplexer (A3)
The diplexer provides a method of using both a receiver and a transmitter on a common antenna. The diplexer, when
properly tuned, provides a transmitter to receiver isolation of 70 dB at any frequency spacing of 4 MHz or 3% of the
operating frequency, whichever is greater. The diplexer has an insertion loss of less than 2.25 dB between the transmit
port and the antenna, and less than 3.0 dB between the receive port and the antenna. The diplexer is capable of handling
60 watts of RF power in the transmit path and provides protection at the receive port to limit receive signals to a maximum
level of +33 dBm (for dBi, dBm, see Glossary).
5-2.11 AC/DC Power Supply (A2)
The AC/DC power supply enables the bi-directional repeater system to operate from the following power sources:
a. External 115V 50/60 Hz AC
b. External 230V 50/60 Hz AC
c. External 10V to 32V DC
d. Internal battery power: one to four self-contained replaceable batteries can be used; use of at least three
is recommended; type BA5590/U Lithium or BB590 nickel-cadmium. For battery operation, use of
the 2 WATT mode will greatly prolong battery life.
All external power sources are accessed through a common connector on the power supply assembly. A unique cable is
provided to accommodate each source. Two toggle switches operate as described in Table 4-2.
The power supply enclosure contains an RF peak detector that produces a DC voltage that is proportional to the
transmitted RF power. The detector is used with the repeater unit as part of the RF output power automatic level control
(ALC).
The power supply enclosure also contains a +28V DC-DC Converter CCA. The +28V DC-DC converter (A2A2)
provides reg28 VDC to the RF power amplifier (A1A6). The power converter operates from a 10-32 VDC input.
Section II. FUNCTIONAL OPERATION OF ELECTRONIC CIRCUITS
5-3 REPEATER CONTROL/AUDIO CIRCUIT CARD ASSEMBLY (CCA) (A1A2)
As shown in Figure 5-2, the repeater control/audio CCA (A1A2) consists of the following major functions:
a. Multiple inputs - The control CCA can accept clear (analog) voice or digital data input from either
Radio A or Radio B, or clear voice input from the local audio connector (MIC) on the front panel. The
local MIC input will only be active if the BDR mode switch is set to one of the COMMS positions.
b. Clear path - The clear signal path provides amplification and filtering of the analog voice signals
received by the BDR and converts the analog to digital signals that can be used by the digital signal
processor (DSP).