I thought that I had eliminated most, if not all of my RFI problems with my ICOM 756 Pro 2 when connected to my homebrew computer interfaces. But I still am having some problems. This is particularly true for the audio cable which picks up quite a bit of RF even though it has isolation transformers. I reduced the problem significantly with large 125 mu permeability rods on both the CI-V cable and the audio cable, but there is still some RF present. I have tried some bypassing capacitors although I found that if too large will cause the CI-V to not work properly. I have been looking at schematics of different units and might try some chokes, but am not sure what to use and where to put them.
The problem is not so much when operating digital modes, but when I want to run power with SSB. I am forced to disconnect the cables from the computer to reduce the RFI affecting my transmitted audio quality. It also seems that my older emachines computer that I use with XP is more of a problem than the newer HP running Vista. This may be due to better shielding or improved design in the newer computer. Has anyone had actual experience with the problem and tried a number of interfaces? Which ones worked the best for you? The two that I am seriously considering are the MicroHam USB Interface II and also the Tigertronics Signalink (not the USB version). I know the Signalink has problems with some modes such as ALE signaling, but am hopeful that it will work good enough for most modes and will likely have the most isolation of anything available. There are a few other interfaces, but they either have worse isolation (West Mountain Rig Blasters) or cost more than I am willing to pay, (Navigator, etc.). 73, Rick, KV9U
