Theory of Operation:
Main Board
3-11
UHF1/ UHF2:
L1601 and C1604 is the inter-stage matching network of the driver amplifier IC,
C1607, C1610, L1604, C1613, C1614, L1605 and C1616 serves as matching circuit of the driver IC
to the final device of Q1601. Capacitor C1607 also works as DC block to the circuit.
VHF:
C927, L907 C920, C921, L908, C922, L909, C924, L910, C923, C928 and C925 are
theelements of the output matching network apart from a transmission-line structure. The Gate
biasing is applied through a biasing network consist of R903, R904, R905, C915 and C917.
700–800 MHz:
L1002, C1002 and C1004 are the inter-stage matching network. Components C1013
and C1023 match the output impedance to the input of the final device (Q1001); capacitor C1013
also serves as the DC block.
3.1.3.2 Power Amplifier Transistor
The power amplifier transistors, (UHF1/UHF2 – Q1601, VHF – Q901 and 700/800 MHz – Q1001)
are Silicon N-channel MOSFETs housed in a high-power, surface-mount, PMM package. To prevent
thermal damage, it is essential that the heat sink of the power module be held in place against the
radio chassis using the RF board screw. All FETs are matched using a lowpass topology. Drain bias
is applied through L1606 for UHF1/ UHF2, L906 for VHF and L1007 for the 700/800 MHz. Gain is
dynamically controlled by adjusting the gate bias. The gate is insulated from the drain and source so
that gate bias current is essentially zero
UHF1/ UHF2:
C1620, C1621, C1622, L1609, C1624, L1610, C1623, C1628 and C1625 are the
elements of the output matching network apart from a transmission-line structure. The Gate biasing
is applied through a biasing network consist of R1603, R1604, R1605, C1615 and C1617.
VHF:
C927, L907 C920, C921, L908, C922, L909, C924, L910, C923, C928 and C925 are
theelements of the output matching network apart from a transmission-line structure. The Gate
biasing is applied through a biasing network consist of R903, R904, R905, C915 and C917.
700–800 MHz:
The input impedance-matching network is C1013 and C1023. A transmission-line
structure and C1019, C1020, L009 and C1021 form the output-matching network. Gate bias applied
through R1003, R1004, C1015 and R1005.
3.1.3.3 Directional Coupler
A directional coupler senses the transmitter forward and reverse power as control signals in the
transmitter's automatic level control (ALC) loop. Isolated ports are terminated with external resistors.
UHF1/ UHF2/ VHF/ 700–800 MHz:
The directional coupler consists of three embedded transmission
lines.
3.1.3.4 Harmonic Filter
The harmonic filter is a high-power, low-loss, low-pass filter. Its purpose is to suppress transmitter
harmonics. The filter also improves receiver out-of-band rejection. Shield SH8 must be in place to
achieve the required stop band rejection.
UHF1:
The harmonic filter apply discrete components as the circuit line up. The pass band is up to
520 MHz while the stop band is above 1200 MHz.
UHF2:
The harmonic filter apply discrete components as the circuit line up. The pass band is
from450–520 MHz while the stop band is above 900 MHz.
VHF:
The harmonic filter apply discrete components as the circuit line up. The pass band is up to174
MHz while the stop band is above 550 MHz.
700–800 MHz:
The harmonic filter uses both discrete components and transmission lines. The pass
band is up to 870 MHz, and the stop band is above 1500 MHz.
Содержание Astro APX 3000
Страница 1: ...APXTM TWO WAY RADIOS APX 3000 DETAILED SERVICE MANUAL ...
Страница 2: ......
Страница 4: ...Notes ...
Страница 6: ...vi Document History Notes ...
Страница 10: ...x Table of Contents Notes ...
Страница 12: ...xii List of Tables Notes ...
Страница 18: ...xviii List of Figures Notes ...
Страница 22: ...xxii CommercialWarranty Notes ...
Страница 46: ...3 20 Theory of Operation Main Board Notes ...
Страница 84: ...3 58 Theory of Operation Bluetooth Notes ...
Страница 147: ...Troubleshooting Waveforms Clocks 6 3 6 2 2 4 MHz Clock Trace 1 Trace recorded at R6113 Figure 6 2 4 MHz Clock Waveform ...
Страница 154: ...6 10 Troubleshooting Waveforms Audio SSI 6 3 4 BCLK Trace 1 Trace recorded at R6107 Figure 6 9 Audio SSI BCLK Waveform ...
Страница 156: ...6 12 Troubleshooting Waveforms RX SSI 6 4 2 DA Trace 1 Trace recorded at R2805 Figure 6 11 RX SSI DA Waveform ...
Страница 157: ...Troubleshooting Waveforms RX SSI 6 13 6 4 3 FSYNC Trace 1 Trace recorded at R2804 Figure 6 12 RX SSI FSync Waveform ...
Страница 159: ...Troubleshooting Waveforms TX SSI 6 15 6 5 2 DA Trace 1 Trace recorded at R2817 Figure 6 14 TX SSI DA Waveform ...
Страница 160: ...6 16 Troubleshooting Waveforms TX SSI 6 5 3 FSYNC Trace 1 Trace recorded at R2807 Figure 6 15 TX SSI FSync Waveform ...
Страница 161: ...Troubleshooting Waveforms SPI 6 17 6 6 SPI 6 6 1 CLK Trace 1 Trace recorded at R2803 Figure 6 16 SPI CLK Waveform ...
Страница 162: ...6 18 Troubleshooting Waveforms SPI 6 6 2 CS Trace 1 Trace recorded at R6602 Figure 6 17 CS Waveform ...
Страница 164: ...6 20 Troubleshooting Waveforms I2C BUS 6 7 2 SCL 5V Trace 1 Trace recorded at R2204 Figure 6 19 I2C Bus SCA 5V Waveform ...
Страница 165: ...Troubleshooting Waveforms I2C BUS 6 21 6 7 3 SDA Trace 1 Trace recorded at R6209 Figure 6 20 I2C Bus SDA Waveform ...
Страница 169: ...Troubleshooting Waveforms USB 6 25 6 10 USB 6 10 1 D Trace 1 Trace recorded at TP F_GCAI_USB Figure 6 24 USB D Waveform ...
Страница 170: ...6 26 Troubleshooting Waveforms USB 6 10 2 D Trace 1 Trace recorded at TP F_GCAI_USB Figure 6 25 USB D Waveform ...
Страница 172: ...6 28 Troubleshooting Waveforms SDRAM 6 11 2 CLKX Trace 1 Trace recorded at TP6308 Figure 6 27 SDRAM CLKX Waveform ...
Страница 208: ...6 64 Troubleshooting Waveforms LF CW on Spectrum Analyzer Notes ...
Страница 222: ...7 14 Troubleshooting Tables List of Board and IC Signals Notes ...
Страница 282: ...8 60 Schematics Boards Overlays and Parts Lists Main Board Block UHF1 84012513001_A Notes ...
Страница 338: ...8 116 Schematics Boards Overlays and Parts Lists Main Board Block 700 800 MHz 84012501002 Notes ...
Страница 390: ...8 168 Schematics Boards Overlays and Parts Lists Main Board Block VHF 84012512001_A Notes ...
Страница 456: ...9 8 Debugging Fixture Powering up Covert Board Notes ...
Страница 468: ...Glossary 10 Glossary Notes ...
Страница 472: ...Index 4 Index Notes ...
Страница 473: ......