Discussion in 'Working Different Modes' started by NY3V, Nov 19, 2010.
I need info on how to operate PSK31 using an MFJ9420 xcvr.
The 9420 seems to be a pretty simple rig. Here's my advice, based on PSK with my TenTec 580∂:
•Use an audio cable to take the headphone output of the radio and input it to the computer's microphone input. (If the radio does not have one, you will have to use the computer's microphone to pick up the radio's speaker... this may cause difficulties).
•You will need to create a custom cable that will take the computer's audio output (headphone/speaker jack) and input it to your radio's microphone input.
•If your radio is not capable of running in VOX mode (I suspect it is not) then you will also need to build a circuit that will switch the PTT on when you send audio from the computer.
You will have to pour over the detailed manual or schematic of the radio to figure out how to connect things the right way.
When using the mic input on the PC (and most laptops no longer have a line input) I have found a 10:1 voltage divider knocks the audio signal down to a more reasonable level. Keying can be done through a serial port using a simple transistor circuit or an opto-isolator -- a decent USB-to-serial adapter will work if all you have are USB ports.