So I bought an ebay patch cable for my Icom 7300 last year, because I had no idea at the time where to get the parts here in Korea (I'm in Seoul) to build my own. The thing works, but there is a low/dull hum when I transmit. If I touch the radio, however, it goes away. I wrote the seller/maker about it (he's a ham who makes patch cables and sells them), and this is what he wrote back: Now here's the problem.... All of the wires are connected as he said they should be. BUT... I don't have a multimeter. If I had had a multimeter, and known how to use one, I probably would have never needed to purchase a patch cable, right? Side note: Multimeters are crazy money here in Korea... I can't just waltz down to a Lowe's or buy one online for cheap. I'm spending $50 for a low-end Chinese one, in Korea. There seem to be some kind of market protections on them, here. So, I asked for a multimeter for my birthday, and my father sent me one he'd purchased on Amazon. Got the multimeter after waiting for shipping...opened it up, and didn't work at all. Numbers going crazy all over the place, no matter what setting. So I'm stuck with a multimeter we paid to ship here (along with my other gifts), and so pissed I don't want to spend $50 in order to check a $10 patch cable. I'm leaving Korea next year, and won't be bringing much of anything, so there is no point in purchasing one now. Anyway... so I still have this hum. I checked all of the connections, and they are correct, per what he said. The radio is an Icom 7300. I have another patch cable (for a dynamic) which works just fine. I had purchased that elsewhere. Hums with two different brands of headsets. Don't have others to try. Any suggestions? I'm sure annoyed by this. Thanks.