Racal Instruments AN/TRC-207, Operation And Maintenance Instructions

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TO 31R2-2TRC207-1
4-11
NOTE
The transmit power for RADIO A will always be at peak power regardless of the front panel
POWER setting because the routing for RADIO A does not pass through the Power Supply unit,
which senses the transmit power and provides gain control back to the power amplifier. Thus,
the POWER setting on the front panel only controls the transmit power of RADIO B.
4-3.2.6.3 Precautions for Cross-Banding.
The tripping of circuit breakers and excessive heating could occur if the 30-88 MHz band is not connected as shown in
Figure 4-7 , ensuring that the 30-88 MHz band RF path is connected through the Power Supply unit. Avoid using
frequencies that are harmonically related, integral multiples of each other, as this could cause the system to lock up by
receiving internally generated signals. For example, avoid using combinations such as 76.55 MHz and 153.10 MHz or
150.2 MHz and 450.6 MHz. Do not use the 150 Hz RX and TX tone in this configuration. If RX and TX tones are used
the same tone must be used in all radios in both bands. A slight degradation in audio level will occur when the system
is configured for cross-banding in the 30-88 MHz band, which could limit the tandem ability in the unencrypted mode.
Either side, TX or RX, of the diplexer can be used but the ANT port of the diplexer must be connected to an antenna or
the RF IN port of the Power Supply unit. Even though one side of each diplexer is unused, the TX and RX frequency
spacing of each diplexer must have the minimum spacing as stated in paragraph 4-3.2. It is important to check that
diplexer tuning is adequate by using the TUNE modes (see paragraph 4-4) and to verify proper operation by establishing
voice communications using both COMMS modes with radios.
4-4 INITIAL POWER-UP AND DIPLEXER TUNING PROCEDURES
Perform the following procedure to power-up the bi-directional repeater and tune the diplexer.
a. Ensure that the RF cables are properly connected to TX connector J2 (4, Figure 4-4) and RX connector
J3 (1, Figure 4-4). Ensure that the proper antenna and diplexer are installed. Ensure that both receiver-
transmitters are programmed in a simplex configuration (same receive and transmit frequencies) for
each channel being used. It is recommended that CTCSS tones (see TO 31R2-2PRC139-1) be used
for repeater operations in the non-secure mode, particularly for tandemed BDRs. All radios in the
intended communications net must be programmed with the same tone. Tones should be set to "OFF"
for secure operation.
b. Ensure that the bi-directional repeater has been installed as described in Chapter 2. Place the MODE
SELECT switch (6, Figure 4-1) in one of the COMMS positions. Place the POWER switch (7, Figure
4-1) in the 2 WATT position. Place the AC/DC POWER switch (2, Figure 4-2) in the DC or AC
position, as applicable, and the DISPLAY switch (1, Figure 4-1) in ON position. If DC power is
selected, place the DC SEL switch (1, Figure 4-2) in the EXT or INT position, as appropriate. Ensure
both circuit breakers are set to ON. Verify that the green POWER LED (5, Figure 4-1) is illuminated.
c. Using the channel select switch on the transmit receiver-transmitter (HHR B), select as the transmit
channel the same channel that is being used by the remote receiving receiver-transmitter.
d. Using the channel select switch on the receive receiver-transmitter (HHR A), select as the receive
channel the same channel that is being used by the remote transmitting receiver-transmitter.
e. Set the diplexer SENS control (2, Figure 4-5) fully clockwise.
f. Release locking ring on diplexer RCV tuning dial (3, Figure 4-5). Coarse tune the RCV tuning dial (3,
Figure 4-5) to the approximate receive channel frequency.
g. Release the locking ring on the XMT tuning dial. Coarse tune the XMT tuning dial (4, Figure 4-5) to
the approximate transmit channel frequency.
h. Place the bi-directional repeater MODE SELECT switch (6, Figure 4-1) in the TUNE A position.
i. Adjust the RCV tuning dial (3) with the red TUNE button (1) depressed until a peak meter indication is
noticed. If the meter produces 100% deflection, turn SENS control (2) counterclockwise until adjustment
of the RCV control yields a peak response less than 100% deflection. Tighten the locking ring on the RCV
tuning dial.