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How to increase the output volume for MFJ-418 Morse code tutor

            I have the MFJ-418 Morse code tutor for prepare the Morse code test. But I felt that the speaker output volume was not enough be listened at the busy or open area. After I opened the case, I found that the LM386 audio power amplifier be used as the speaker driver. And the pin 1 and pin 8 of this amp. was disconnected. Pin 1 and pin 8 is for adjust the gain. Just 20 times gain when disconnect these two pins. I am now connect a 10uF 16V electrode capacitor at there for maximize the gain to 200 times. Although there is some distortion here when the volume control at the maximum position, it still clear, readable, loud and clear. The output volume rise about 10dB more. Please see the datasheet for detail as follow.

Inside the box	PCB analysis

    Datasheet for LM386 Low voltage audio power amplifier