EB1200 Power Amplifier Protection Circuits
1. Overheat protection.
If the temperature of the aluminum cooling radiator exceeds + 45C, the PWM system
will smoothly increase the fan speed.
When the radiator temperature reaches + 60C, the PTT circuit is broken and it will be
impossible to turn on the amplifier for transmission, until it cools down to + 50C.
2. Protection against exceeding the maximum permissible output power.
If the output power level exceeds the permissible threshold, the protection will operate,
which disconnects the + 50V supply from the output transistors. To reset the protection, turn off
the + 13.8V power supply for at least 5 seconds.
3. High VSWR protection.
If the VSWR in the load exceeds 2.0: 1, the protection system will operate. To reset the
protection, turn off the + 13.8V power supply for at least 5 seconds. If the protection is
triggered, we recommend checking the antenna SWR. If you cannot match the antenna, but it
works, use an antenna tuner.
4. Protection against exceeding the maximum permissible current.
If the current value of the output transistors exceeds the permissible threshold, the
protection will operate, which disconnects the + 50V supply from the output transistors. To reset
the protection, turn off the + 13.8V power supply for at least 5 seconds.
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