A simple opto isolated keyer circuit
by PY2TI
Use it to key your radio via serial interface and your logging program.
If you run contests using a logging software like CT, TR; it probably is useful to key your transceiver. There are two possible conection of your computer to a radio, serial interface or parallel interface.
To people who use your computer network conected, serial wouldn't be possible to use it, but if you are single operator and single computer like me, it will be free. So it is a scheme that i'm using.
This is a simple to build circuit, it is so small, i built it inside a female DB 25 conector.
Take a look at schematic in figure 1.
The circuit uses an opto-coupler type 4N25, it give an isolation of computer to radio keying line.
All of components is easily found at electronic stores, a small piece of bread board that fit inside a DB 25 conector can be used.
I tested this circuit in the last may CQWW WPX contest and it worked flawlessly.
Please remember : this is designed for serial interface for parallel interface it needs changes in the conector pins.
I hope that this little article can help you to keep your radio isolated from the computer. So if it works as your expect, please tell me. Send me an E-mail or pictures from your city i'll be very happy, and a good way to know how many people build then. Good luck and see you in the contests. CT , TR IS SOFTWARE I USED FOR TEST PURPOSE , NO OTHERS WERE USED, AND IS PROPERTY OF THEIR RESPECTIVE OWNERS.
j. rideo - py2ti
E-mail : py2ti
address: R. MIN. JOSE GR ALKMIN, 111
12233-510 - SAO JOSE DOS CAMPOS - SAO PAULO - BRAZIL
