AR 10052412, Operating And Service Manual

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Model 5000A225C
40 Rev A
3.2.3 A4 Four-Way Splitter
The Four-Way Splitter is a broadband splitter. The input signal is split into four equal-amplitude, equal-phase
signals. The amplitude of each signal is 6-6.5dB below the input signal when all outputs are terminated into
50
Ω
loads.
3.2.4 A6-A9 Four-Way Splitter
The Four-Way Splitter is a 180
°
broadband splitter. The input signal is split into four equal-amplitude signals.
The amplitude of each signal is 6-6.5dB below the input signal when all outputs are terminated into 50
Ω
loads.
3.2.5 A14-A29 Final Module Assembly
The Final Module Assembly consists of RF matching circuits, an RF transistor (Q1), a bias control circuit, and
a fault detection circuit.
The RF input is fed to a 4:1 balun transformer composed of T1 and T2. The output signal of the 4:1 transformer
is connected to the gates of Q1. The drains of Q1 are connected to a 4:1 balun transformer composed of T3 and
T4. Q1 has approximately 50 VDC applied to both drains at a total current of 18A. The RF stage has
approximately 19 dB of gain and an output compression point of 250W or greater.
The current through Q1 is monitored by U1. The output of U1 is fed to an op amp (U3) which has a reference
voltage on the non-inverting input. U3 compares the output of U1 to the reference voltage and generates an
error signal. This error signal varies the gate voltages of Q1 which in turn controls Q1’s current draw.
U5 is a comparator that monitors the output of U1 and generates a fault signal if the drain current varies outside
normal operating conditions. It also monitors the module temperature via a thermistor (R31) and generates a
fault signal if the module heatsink exceeds approximately 80 o C
3.2.6 A46-A49 Four-Way Combiner
The Four-Way Combiner operates in zero-degree configuration with a broadband range of .01-225 MHz. The
combiner is designed to tolerate loss of input signals at full power.
3.2.7 A50 Four-Way Combiner
The Four-Way Combiner operates in 180-degree configuration with a broadband range of .01-225 MHz. The
combiner is designed to tolerate loss of input signals at full power.
3.2.8 A51 Bi-Directional Coupler
The A51 Bi-Directional Coupler takes a sampling of the forward and reverse RF output signal for use in the
automatic level control and display circuitry as well as the RF forward and reverse sample ports. The RF
coupling of the forward and reverse coupled ports is approximately 76 dB for the amplifier internal ALC use
and 890 dB for the sampling ports.