My loss is your gain. I purchased this kit so I could use my desktop computer to key my HF rig for FSK and CW. However the add on serial port in my computer evidently does not supply enough current to drive the optoisolators into full saturation. (The optoisolators in the kit draw 11.5 mA at 12 VDC) It does not drive the output of the optoisolators low enough to key my TS-590SG. The low logic level is about +0.5 VDC. There are evidently many rigs out there that will work with this interface, but my TS-590SG would not. You can see the schematic and more about the kit at http://thetower.us/FSK/index.html The kit originally cost $20.00 plus shipping and the enclosure cost $8.50. If you would like to give this interface a try, I will sell it for $10.00 plus USPS Priority Mail delivery ($7.20). Payment by Cash, Check, Money Order or PayPal. E-mail direct to TimWS4V@gmail.com No warranty, but everything is just as I received in the kit and what you see in the pictures.