There are many brands of interface available to connect a PC to a ham radio transceiver. Often home-brew interfaces are used. They all do essentially the same thing.
They key the radio to transmit, pass a signal based on the mode of operation from the PC to the radio, then un-key to go back into receive mode.
Some automatically bypass the microphone
Sites about soundcard interfacing
- Understanding soundcard interfacing By Ernie Mills WM2U
- Digimaster from ZLP Electronics. A variety of interfaces and connecting cables are available.
- PCInterfaces In both kit and pre-constructed form.
- Microkeyer USB interface from Microham. Other models are available.
- SignaLink from Tigertronics. Two models available, one that used the computer soundcard and DB9 connection, the second has a built in soundcard and connects via USB
- Rascal GLX from Bux CommCo. Available in kit or constructed form. A variety of cable options are also available from the site.
- Rigblaster from West Mountain Radio. Has interface models with both USB and RS232 DB9 connections. Includes inbuilt rig control capability.
- RigExpert USB interfaces and MixW software.
- VA3TO linking interface. Operates under EchoLink software and doubles as a soundcard interface for various digital modes.
Interfaces can be fairly simple and thus are easily home-brewed. Here are 2 schematics. The first one is for PCs with a serial port being used for PTT, the second one for an Asus Eee netbook. It uses a VOX circuit for PTT.