Codan Radio Communications AMP-4-470 User Manual
2
Power Amplifier AMP-4-470-30-00
1.
General description.
The power amplifier (PA) is a one stage unit, working in AB-class operation mode. In addition to the
power amplifier section, the PA contains the power control, status monitoring and protecting circuitry,
as well as voltage regulation for supplying the RF and main control circuits.
The output power may be controlled either by the external analog signal (remote control), or by
potentiometer, accessible from the front panel (local control).
The voltage regulator turns on, when all four of the following conditions are present:
power amplifier section, the PA contains the power control, status monitoring and protecting circuitry,
as well as voltage regulation for supplying the RF and main control circuits.
The output power may be controlled either by the external analog signal (remote control), or by
potentiometer, accessible from the front panel (local control).
The voltage regulator turns on, when all four of the following conditions are present:
-
remote control voltage (in the case of remote control) is greater than 1 V;
-
input power is not less than 0.5 W;
-
the case temperature does not exceed + 85°C;
-
power supply voltage does not exceed 17 V.
If any of three first mentioned conditions is not met, unit remains in stand-by mode.
The PA is provided with a forced air cooling system and is protected against load mismatch, overheating
and overvoltage. The load mismatch protection smoothly reduces output power as the load VSWR
increases above 2:1.
Three LED on the front panel indicate the unit status. The green LED “TX” shows that the output power
is between the nominal (>30 W) and minimum set power ( ~20 W). The red LED “G/F” (general fault)
turns on during overheating or overvoltage. The red LED “VSWR” is active when the load VSWR is
above 2:1.
The PA has three outputs (open collector) for remote status monitoring. In an alarm state, the level is
pulled low.
The block diagram of PA is represented in Fig. 1.
2.
General parameters.
-
Frequency range, MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450 - 512;
-
Output power, W;
o
nominal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 30;
o
minimum set by local or remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 20;
o
in stand-by mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 0.2;
-
Harmonic level at the output, dBc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < -70;
-
Reverse intermodulation attenuation, dB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 40;
-
Input power, W:
o
nominal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0;
o
maximum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.0;
o
guaranteeing the stand-by mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 0.5;
-
Input VSWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 1.8;