Digimode
PC to TRX galvanic isolated Interface
This interface is galvanic isolation of the transceiver from PC computer. Audio input and output paths are separated by transformers; optocouplers serve to isolate the digital paths, PTT and CW KEY.
It
was built for Icom
IC-718 but can be used for any other radio. Interface support PTT
keying over
RS232 RTS (pin 7) and CW keying over RS232 DTR (pin4) line. LE diode
LED2 glow
green when radio is in RX state. LED3 glow red when PC software switch
radio to
TX state. If you use some of contest or logging software for automatic
CW
keying, LED 4 will glow in rhythm of Morse letters.
Connection from PC to
interface goes to 9 pin subD female connector. It takes 3 pins:
- Pin
7 – RTS (RX/TX
keying)
- Pin
4 – DRT (CW
keying)
- Pin
5 – PC GND
Connection from interface to TRX goes via 9 pin subD male connector. Same connector is used for audio channels from interface to TRX. This is connection cable for ICOM IC-718.
| Interface | Description | Icom |
| Sub D - male | 13 pin ACC Socket | |
| PIN 2 | PTT | 3 - Send |
| PIN 3 | CW Key | |
| PIN 7 | TRX GND | 2 - GND |
| PIN 8 | Line out PC | 11 - Modulator input |
| PIN 9 | Line in PC | 12 - AF detector output |
Schematics diagram
Schematics made with Abacom sPlan. Download free viewer at http://www.abacom-online.de/uk/html/dateien/demos/splan-viewer60.exe
Download schematics as:
PCB layout and parts placement
PCB is simple, one sided. I use toner transfer method to make this one. There is instruction for this method at my site. For now it is only in Serbian, but soon, it will be English to. Here you can find PCB layout in different formats so you can choose what is best for you.
PCB layout made with Abacom Sprint 5.0. Download free viewer at http://www.abacom-online.de/uk/html/dateien/demos/ViewLayout50.exe
Download PCB layout as:
Download parts placement as:
Realization
I did not save PCB space so everything can be accessible and logically
placed. You can notice that I used old PC mother board connectors for
sound input and output. Two reasons for that. First, it is
easy to
find old PC mother boards at my scrap pile, and second, it's hard to
make mistake in audio cables if you use connectors of right colors. So,
just connect same color at interface and PC side.
I
