A simple way to do it is to use a high-speed signal relay like the Omron G6A-274P40-DC12 (Mouser 653-G6A-274P40-DC12) which switches in typically 3ms (spec is 5ms) and handle 3-amps. I've used these relays in several QSK switches (info in various articles on my website at www.ad5x.com
). Put one of these relays in a little Bud box. Feed the amp-enable output of the opposite radio to this box to enable the relay to switch the antenna to ground when the other transmitter transmits.
The FT-950 has a 15ms minimum amp-enable-to-RF-out delay. The TS480 has a minimum 10ms amp-enable-to-RF-out delay. Both well above the 5ms spec'd switching time of the relays.
Phil - AD5X