In 2005 I bought a TKM NC 2210 Ramp Tester from Sporty's Pilot Shop. It works fine to test the function and performance of nav receivers in response to VOR, Localizer and glide slope signals. The calibration sticker showed an expiration date in 2006. I like to have the unit calibrated and I found that the manufacturer is the best source. If you have a need for calibration of one of these units contact them at email@example.com
. The standard charge is $95 plus shipping and handling.