RFI shouldn't be an issue, but it doesn't hurt to take precautions.
I use an older RIGblaster plus with my IC746 non-pro. I take the receive audio off the aux output in the back. PTT and transmit audio are handled through the front panel mick connector, and the RIGBlaster provides an input for your microphone. I think the Signalink might be a better idea, and the RigBlaster folks also have a similar unit now. The Rigblaster really doesn't do much on receive - in fact it does nothing in my setup. It's a direct connection from the aux audio out (NOT the speaker) to the mic input on the computer. Once you have that working, you can move forward with transmitting. If you are using the mic jack on the front of the radio, you could use VOX to key the rig. That's basically what SIgnalink does, anyway, and it avoids conflicts with USB to Serial junk.
I have several different software programs that I like to use. FLDIGI is what I use most often, but Ham Radio Deluxe and others work well. I am not using the CAT interface right now, but it works fine.
If you are going to use a USB to Serial adapter, shop around and find those based on the FTDI chip. I've had nothing but grief lately with anything that calls itself Prolific. Ever since upgrading my #1 ham radio computer to the latest fixpack for WIn 7, it won't recognize Prolifics. I had the same problem on another Win 7 machine, and removing the update eliminated the problem. But, on the one computer, I have had no joy getting Prolific to work , with or without the Windows update. I've tried all the many different drivers out there, and no joy. FTDI chipset devices work perfectly on all of my computers, no hassle. It just takes longer to find the FTDI based units. Prolific blames it on countefeit chips. Since this problem exists with so many Prolifics, I guess they are all counterfeit.
Anyway, the 746 does a good job on digi modes. Another hint - turn OFF the AGC and use the RF Gain control. It will help a great deal!
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