Sound Card to Radio Interface

Acoustical Coupling

The least expensive way and maybe the only way is acoustical coupling. Just hold the radios microphone to the computers speaker and drap a microphone over the radios speaker. You can use most headphones as microphones. A laptop may not have a jack for external microphone but the built-in microphone(s) may be enough.

To transmit data, place the headphone(connected to the computer) over the radio's mic
To transmit data, place the headphone(connected to the computer) over the radio's mic.

To receive data, drape a microphone over the radio's speaker
To receive data, drap a mic over the radio's speaker.

Another way to receive data, is to use a headphone connector to the computer's MIC INPUT and draped over the radio's speaker
Another way to receive data, is to use a headphone connecter to the computer's MIC INPUT and draped over the radio's speaker

Hardwire Interface

I use a interface based on one the Howard S Teller KH6TY design.
I added a coupling capacitor(C3) and 2.2k resistor(R6) for radio that combine the mic and ptt on the same jack.
modified kh6ty interface for some radios


My circuit cardboard interface
My circuit cardboard interface using

My Yaesu FT-1802 does not have an audio data port so...


my interface needs to have one plug for the speaker jack in the back
my interface needs to have one plug for the speaker jack in the back


one for the mic jack front
one for the mic jack front

My Yeasu FT-857D has an audio level interface and a built in VOX circuit. The audio level interface uses a 6-pin miniDIN.


Yaesu FT-857D Audio Port in the back
Yaesu FT-857D Audio Port in the back


I cut the socket end off a PS/2 keyboard extension an solder three wire directly to the usb sound adapter.
I cut the socket end off a PS/2 keyboard extension an solder three wire directly to the usb sound adapter.


The usb sound adapters have two stereo jacks but the mic is mono, tip and ring are connected so use a stereo plug for the mic
The usb sound adapters have two stereo jacks but the mic(yellow) is mono, tip and ring are connected so use a stereo plug for the mic.
I just solder directly to the board.