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This is not a sophisticated automatic keyer but it is lot QRP to build and to have fun operating it.
When the paddle is connected to the DOT terminal, C1 starts to charge. When C1's charge reaches sufficiently high value, it causes the transistor BC157B to conduct and pulls the relay and key the transmitter. Paddle connection is then momentarily disconnected through the relay, discharging the capacitor and thus stopping the transistor to conduct. The relay releases and paddle connection is restored to ground. The cycle repeats until the paddle is released.
The dash paddle works in the same fashion. The 10 k preset set the dot - dash ratio. The 47 K potentiometer is mounted on the front panel and acts as speed control. 2K2 preset should be adjusted for soft most operation of the keyer. Can you imagine any simpler QRP Keyer?
Circuit By K P S Kang. Published is Indian Ham 4/1997
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