6: Power Amplifier Board
PRC1099A-MS
6-3
For final RF power amplifiers Q4 and Q5, the bias regulator circuit operates
the same as for the driver amplifiers. D2 senses the Q5 temperature and drives
bias regulator U4 at pin 3. U4 biases the base of Q7 up or down according to
the input FTSENS which drives RF power amplifiers Q4 and Q5. The
quiescent operating point for the final stage is set by adjusting R24.
6.1.5
Temperature Switch
The PA board includes a temperature-sensitive resistor (thermistor TH1) with
a positive temperature coefficient to prevent damage to RF power amplifiers
Q4 and Q5 from overheating. Thermistors change resistance with
temperature; this means that as the thermistor temperature increases, its
resistance increases. Bipolar transistor Q8 forms a voltage divider with TH1
and conducts when the heat sink temperature exceeds 80°C, pulling the LOW
POWER line to ground. This forces the radio RF power output to 5W or less
until the RF power amplifiers cools. TH1 is mounted in a hole in the board
heat sink under the PA board and normally measures about 150 ohms at room
temperature.
6.1.6
Specifications
Note:
These specifications are subject to change without notice or
obligation.
Table 6-1 Power Amplifier Board Specifications
Characteristic
Description
Transmit
Current
+8 VDC at 65 mA
+12 VDC at 250 mA (quiescent)
+12 VDC at 3.6A (20W, CW, output)
Frequency
1.6 to 30 MHz
Output
20W, CW into 50 ohm
Input
0 ±2 dB
Gain
43 dB
Содержание PRC1099A
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Страница 49: ...3 Audio Filter Board 3 14 PRC1099A MS Figure 3 2 Audio Filter Board Component Locations 738221 Rev J ...
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Страница 71: ...4 1650 kHz IF Board 4 6 PRC1099A MS Figure 4 2 1650 kHz IF Board Component Locations 738028 Rev D ...
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Страница 86: ...5 Mixer Board 5 10 PRC1099A MS Figure 5 4 Mixer Board Component Locations 738217 Rev H ...
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Страница 103: ...6 Power Amplifier Board 6 6 PRC1099A MS Figure 6 2 Power Amplifier Board Component Locations 738617 Rev C ...
Страница 117: ...7 Antenna Tuner Board PRC1099A MS 7 9 Figure 7 2 Antenna Tuner Driver Board Component Locations 738346 Rev B ...
Страница 118: ...7 Antenna Tuner Board 7 10 PRC1099A MS Figure 7 3 Antenna Tuner Board Component Locations 738027 Rev D ...
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Страница 131: ...8 Synthesizer Board 8 6 PRC1099A MS Figure 8 2 Synthesizer Board Component Locations 738025 Rev A ...
Страница 163: ...9 Processor Board 9 14 PRC1099A MS Figure 9 2 Processor Board Component Locations 738218 Rev B ...
Страница 178: ...10 Display Board 10 8 PRC1099A MS Figure 10 1 Display Board Component Location Diagram 738220 Rev G ...
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Страница 185: ...11 Junction Board 11 4 PRC1099A MS Figure 11 1 Junction Board Component Locations 738222 Rev F ...
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Страница 207: ...13 Internal Options PRC1099A MS 13 7 Figure 13 3 ALE Board Component Locations 1 of 2 738215 Rev B ...
Страница 208: ...13 Internal Options 13 8 PRC1099A MS Figure 13 4 ALE Board Component Locations 2 of 2 738215 Rev B ...
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Страница 247: ...Index 6 T Technical specifications 1 2 Transmit path 2 4 U USB 1 4 see also Modulation modes USB LSB mode V VSWR 1 4 ...