This was pretty easy. I just put the 500 kHz antenna (directional properties at 7 MHz unknown) on the R75, and ran Argo. Here's a shot of the start of the 0630 run: http://www.w1tag.com/files/HAARP1.jpg The echo was visible for most of the first half hour, but disappeared from 0700 to almost 0725. The Doppler shift was definitely wider at the end. John A.