High power—Technical description
232 NGT Transceiver System Technical Service Manual
Transmit path
High-power PA & Antenna Control PCB
This unit provides the control interface between the NGT, the power amplifier and the
SG235C antenna tuner. The NGT antenna control output is reconfigured to supply clock,
data and PTT information to the antenna controller.
When the frequency band of the PA changes, the NGT sends data via the clock and data
lines to the microprocessor IC3. IC3 decodes the data and drives IC4 to select one of the
seven PA bands on J2. Switch S1 is read by IC3 and is used to set up the system for
different external PA types.
The PTT signal is connected to the PA via IC2/A/B V5 and V7. The microprocessor IC3
can disable the PTT by switching V6 on.
When the SG235C antenna tuner is connected to the system at J1, the tuner reset line is
driven low when the NGT is scanning. IC3 also drives the LED (see page 226, LED
indications on the NGT).
Drawing 04-03377
Table 14: Position of digi switch S1
Digi switch
position
Mode Frequency range to band selection
0 Datron TW500A/TW1000A Band1 Not used
Band2 0 ≤ f < 3MHz
Band3 3 ≤ f < 5MHz
Band4 5 ≤ f < 8MHz
Band5 8 ≤ f < 13 MHz
Band6 13 ≤ f < 20 MHz
Band7 f ≥ 20 MHz
1 Datron TW500D/TW1000D Band1 Not used
Band2 1.6 ≤ f < 3MHz
Band3 3 ≤ f < 5MHz
Band4 5 ≤ f < 8MHz
Band5 8 ≤ f < 13 MHz
Band6 13 ≤ f < 20 MHz
Band7 f ≥ 20 MHz
2–15 Undefined Future use
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