6: Power Amplifier Board
6-2
PRC1099A-MS
6.1.1
Predriver Amplifier
Predriver amplifier U1 is a class A amplifier with fixed bias. The predriver
amplifier stage includes a gain leveling network that consists of C59, R60,
R61, R62, and R64. The output from the collector is coupled through
broadband transformer T1. The stage is powered from the regulated T8 line
and is switched off in receive mode.
6.1.2
Driver Amplifier
The driver amplifier stage consists of linear broadband amplifiers Q2 and Q3
in a push-pull amplifier configuration. The driver amplifiers operate in class
AB with a regulated bias supply and grounded emitters. The input from the
predriver amplifier is coupled through broadband transformer T1. The driver
amplifiers uses collector-to-base feedback provided through R7A and C14,
and R10 and C10. The emitters are grounded. The output is coupled to the
final amplifier through broadband tubular-type, ferrite-loaded transformer T2
with a push-pull primary and secondary. The driver amplifiers operate directly
from the 12V supply and is switched off by the bias supply (DBIAS).
6.1.3
Final Amplifier
The final RF amplifier stage consists of RF power amplifiers Q4 and Q5 in a
push-pull configuration. The RF power amplifier transistors are designed for
SSB service in the HF range. The input from the driver amplifiers is coupled
through T2. The transistors operate in class AB using collector-to-base
feedback R16/C20 and R13/C23. The transistor bias is derived from the bias
regulator circuits.
Output transformer T3 is a tubular-type, ferrite-loaded transformer with a
push-pull primary and a single-ended 50 ohm secondary. The final amplifier
stage operates directly from the 12V supply and is switched on and off by
controlling the bias supply. The final amplifier is capable of power outputs of
30 to 40W.
6.1.4
Bias Regulators
Driver amplifier bias regulator circuit U3 compensates for temperature
variations by adjusting the driver amplifier bias voltage. Driver amplifier Q3
temperature is sensed by diode D1. The current through D1 increases as
temperature increases, which decreases the DT SENS voltage. DT SENS is
scaled by R48 and R33 and then applied to the non-inverting input of op-amp
U3. As the voltage decreases, the output of Q6 (DBIAS) decreases, lowering
the base bias to driver amplifiers Q2 and Q3. The quiescent operating point
for the driver stage is set by adjusting R19.
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 ...