Chris,
I used to use one when I was racing karts at NHMS. It worked fine until somebody decided they wanted segment times and placed 2 more transmitters out on the track. I've seen where everyone puts their transmitters on the pit wall at start finish now.
I went out and bought a Rumblestrip GPS predctive timer for 395 and have been very happy with it.
http://www.rumblestripracing.com/ind...&product_id=50
Good Luck...
Are you coming to NHMS this weekend, I did not see your name on the entry list.
Regards
Abhi