This picture shows the PCB layout of components for a simple Interface to connect Rig to computer sound card and provide RS232 connection.

Click on image to see component layout annotated.

Click here for circuit diagram

This picture shows the track side of the PCB board as it was originally made when an opto isolator was not used. The pads however were spaced sufficiently that a "work around" was possible to incorporate the opto isolator, and transistor and protection diode.

Look for the emitter leg identifier and the other leg follow as emiter base collector.

such information on the transistor can be found in data book / catalogues

By using this method there is a reduction of cables where EMC problems might occur.

Component list
Resistors		Capacitors		Semiconductors
Value	Required	Value	Required	Type	Required
1k8	2	NONE		Opto isolator 4N25 or similar	1
Horizontal Preset 22k	2	Wire wound		Diode 1N914 or 1N4148	1
		Isolation transformers Farnell's code 177-497	2	Diode 1N4002	2
				Transistor BFY51	1
Other components	Led to your taste in colour and intensity plus resistor for current limit assuming 25v feed from RS232 (allowed for 1k8 in resistors above amend as necessary)			Suitable sized box to hold board plus cable ties to lock cables to board
2x stereo 3.5mm plugs to link to sound card			9 or 25 pin connector as appropriate to computer to link to RS232
Plug to mate with rig mic socket of rig Plug to mate with external speaker socket of rig			Small Single Pole Single throw switch to inhibit PTT line on Computer start up
Small speaker, suitable for your rig to hear the DATA tone incoming			About 3 metres of screen single cable
Single sided PCB material and etch fluid if you are to make your own PCB - do not attempt this if you have not experience of making PCBs as the etch fluid need much care in use			About 2 metres of screen multi core cable (6 plus Screen)