N1LAF
04-17-2013, 10:47 AM
This is my interface for my radios, cheap and easy. I know it works with Kenwood and ICOM radios, and probably with all others. Also works with laptop, desktop, and USB to Serial hardware.
http://paulfelgate.com/hamradio/serial/serialschematic.gif
Voltages from hardware handshake lines that are not used supply power for the interface. Diodes D1 and D2 will allow only positive voltage to the circuit. Capacitor C1 filters any voltage supply transients. Since serial interfaces can be 5VDC or 12VDC, a zener is needed to reduce 12VDC down to 5VDC. MOSFETs are used as interfaces. They supply voltage separation. R1 provides pull-up for serial in, and for Kenwood radios (At least the TH-F6A), it needs an input voltage. D3 only allows positive voltage to the MOSFET, R2 is a bleeder, as well as R5.
For rig control - this 'Open Collector' (actually Open Drain) can be used.
http://paulfelgate.com/hamradio/serial/ptt.gif
ICOM's uses a single serial line (which is a pain, have to use collision detect to ensure the output got through), and the Kenwood is full duplex.
http://paulfelgate.com/hamradio/serial/connections.gif
http://paulfelgate.com/hamradio/serial/serialschematic.gif
Voltages from hardware handshake lines that are not used supply power for the interface. Diodes D1 and D2 will allow only positive voltage to the circuit. Capacitor C1 filters any voltage supply transients. Since serial interfaces can be 5VDC or 12VDC, a zener is needed to reduce 12VDC down to 5VDC. MOSFETs are used as interfaces. They supply voltage separation. R1 provides pull-up for serial in, and for Kenwood radios (At least the TH-F6A), it needs an input voltage. D3 only allows positive voltage to the MOSFET, R2 is a bleeder, as well as R5.
For rig control - this 'Open Collector' (actually Open Drain) can be used.
http://paulfelgate.com/hamradio/serial/ptt.gif
ICOM's uses a single serial line (which is a pain, have to use collision detect to ensure the output got through), and the Kenwood is full duplex.
http://paulfelgate.com/hamradio/serial/connections.gif