I am using the "Swing Speed Radar with Tempo Timer"
manufactured by Sports Sensors Inc. and it is set up according to the directions that come with the unit. It is on loan to me from one of my local students. Now, whether it is calibrated or not I don't know. But we did use it at the beginning of the month during our first lesson, and I clocked 114 mph, 116 mph. And the speed registered by it is consistent with what I had on a launch monitor at Golf Galaxy earlier this year.
I had read that some LD competitors noticed that their maximum club head speed is forward of the ball location, so I experimented by moving the radar forward and back by as much as a foot either way. It didn't make a difference.
I don't really care what the final speed number is - what is very interesting is increase in the measurements after just four sessions. I mean from 115 avg to 122 avg and with a high of 128 mph...well if it hadn't happened to me I wouldn't believe it.
Never quit til you have a swing you'll never forget!