[Elecraft] K3 has "Zero" Output??!!

[Mike Furrey]

Just as the 160 meter contest was starting my shack computer crashed big time ( power supply failure) . I unpacked my other computer, loaded and configured software, installed drivers for usb to serial cables and then it was time to give it a quick test before contesting. My dummy load was still packed (new qth here) so I turned the power output on the K3 down to "Zero" and hit F4 to send my call. Much to my surprise I heard my call and a report come back to me!  I hit F2,  sent my exchange and completed the Q. NO3M must have  a suburb set of ears to hear that "Zero" output!
Soooo ... when I turned the power output down to "Zero," What is the power output?????? I only have a Bird meter with a 250 watt slug in it and the meter doesn't wiggle at "zero" output. 
That was a fun Q!
73, Mike WA5POK