Hi, all.
Ron,
Your track/field users should be aware that operating out-of-band is not only dangerous, but is _illegal_. (U. S. 47CFR95.207)
The gist of 95.207 is:
27 MHz band - Surface only
72.01-72.99 MHz - Air only
75.41-75.99 MHz - Surface only.
If you run into someone who just won't cooperate, a letter from the FCC can be a real wake-up call!
Cheers,
--Bob
AG4PV