I'm going to be connecting my new Yaesu FT-991 to the Henry 2k in my shack. The Henry uses a 12V T/R relay and the transceiver only needs to ground the center pin of the RCA jack to key the amp. My Kenwoods were able to do this without a problem, but the Yaesu does not appear to use an internal T/R relay for external linear amp keying. The Yaesu manual is less than helpful when describing the connections on the TUNER/LINEAR jack on the back panel of the amp. I'm assuming that if I connect the RCA to the pins for TX GND and GND, it should provide the path to ground to key the amp. I ordered a cable on eBay that should arrive today or tomorrow, and my plan is to see which pins the connector is actually soldered to. My assumption is that they connected it to the 13.8V pin and TX GND connector. I don't think it will hurt the T/R relay in the amp, but would it damage the transistor keying in the transceiver? I was thinking that if the transceiver is keying 13.8 volts on transmit, I could just use an external relay with the transceiver keying that relay, which would then close the coil on the Henry and key the amp. Am I getting too complicated with this setup?