Voice Keyer for FT-897 (and similar)
There are several voice keyers on
the marker already. However, I wanted something as small and
portable as the TCVR FT-897 is.
The keyer is embedded into a small plastics box.
It is plugged into the MIC cord. This way it doesn't require any extra power supply.
The keyer is controlled by the buttons on the MIC:
UP - record
DWN - play back
FST - play repeatedly
All the parts are mounted on one single PCB including the two RJ-45 connectors.
This is the top face of the board.
The bottom face of the PCB.
Comments to the schematic:
For the recording and playback it uses Winbond ISD1730 chip.
CMOS 4053 switches the AF paths instead of a relay.
NE555 makes a delay around 3 sec between two playbacks.
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