Voltmeter wired into the circuit and set up to measure amperage.
703 Plus current draw:
On / Mute: 0.49A
On / Max Vol: 0.53A
On / Mic Keyed SSB: 1.03A - 1.06A
On / Mic Keyed RTTY: 2.33A
On / Calling CQ SSB: Saw a max of 1.95A. I'd guesstimate an average of 1.55ish Amps during transmit.