Hello, I have the hard to find cable with two prong connectors on each end, which connects the T4/TR4 Transmitters to the L4 amplifier. This is the VOX / amp TR switching cable. There was one on ebay that sold couple of weeks ago for $56. I don't have use for it any longer, so email me if you need one with a reasonable and fair offer. 73 Saad N5FF