Overview

The idea behind this project was to construct a microconrtoller based CW beacon Keyer that could be used in a variety of ways, the transmitted string needed to be programmable and the parameters of transmission needed to be adjustable. It was decided early on that the configuration of the beacon would be performed via a PC running a suitable terminal program.

The final design was required to directly key a transmitter (via the CW Key output) or alternatively to supply PTT/Audio controls to directly drive a standard transmitter.

A detailed outline of the operation of the software for the keyer can be found in the download files at the bettom of this page.

Circuits and Layouts

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.

Download:

The files for this project are availiable here:

1. CW Beacon - Control software Overview
2. CW Beacon - General purpose circuit - Layout
3. CW Beacon - General purpose circuit - Circuit Description
4. CW Beacon - General purpose circuit - Stripboard Construction
5. CW Beacon - General purpose circuit - Extended
6. CWBeacon - HEXCode V1-04b