The circuit is based on the popular 16F88 microconrtoller the design of which has a number of pre-configured modes, the mode in which the unit operates depends on the state of two digital inputs pins. The state of these inputs is read on power up. Again the function of each of these pins is discussed in the download files at the bottom of the page.
This circuits was then transferred to stripboard in the following way.
The constructed circuit was then physically connected to external peripherals as below. This then provided a PC communications port for configuration, external function controls, Tx relay with N/O and N/C contacts and audio out for connection to the microphone input of a suitable transmitter.
The final assemble was then housed in an aluminium case.
The keyer has been tested with a IC2E handheld and gave good performance for DF. The unit above was given to a radio club member for testing/use in a microwave beacon.