Combine the butter, salt, lime juice, chili powder, and pepper in a 9×13 flame-proof pan (aluminum foil drip pans work great for this).
When the grill is ready, set the pan on the grate and heat just until the butter is melted. Remove from heat, but keep warm nearby.
Grill the corn directly on the grate, turning a little it every minute or so until the kernels are a deep yellow and have started to lightly blackened (about 5 minutes). Move ears to basting pan and rotate to coat. Return to the grill and cook for another 2 to 3 minutes, turning often. Remove to the basting pan, rotate again to coat, and then move the pan full of corn to the grill. Let it sit on the grate until everything starts to bubble, about a minute.
Rotate one more time in the butter baste and serve hot off the grill.