| >Problem is, they are | >prior to the frequency chage that occurred some time ago | | Radios that are not 1991-type accepted, i.e., "narrow band/gold | stickered", can not be upgraded. The whole RF section must be | replaced. With the price of excellent computer radios now-a-days, | you're better off scrapping them and buying new units.
To expand on that, the transmitters could probably be modified to be narrow-band, and while they'd certainly work perfectly (and be perfectly safe) after that, I believe this isn't legal. (Not that I claim to understand the FCC regulations.)
(Don't ask this group for advice regarding FCC regulations -- that is, unless you like getting several totally different, mutually exclusive answers :) )
The receivers cannot be reasonably modified to be narrow band. They can legally be used, even today with modern equipment, and will work fine, but they'll pick up interference from adjacent channels. Don't use them except maybe in your shop and then only for testing. If you do that, be sure to mark them very clearly so you don't accidently use them in a plane.
(In theory the receivers could probably be modified to be narrow band, but they're so small and everything is so crammed in there, that once you pay somebody $40/hr to do it, you could have bought several brand new narrow band receivers for the cost. The transmitters are easier, but again, it's cheaper to just buy modern equipment.)
Don't throw away the transmitters, though -- depending on what you've got, they might make nice buddy boxes. Do remove the crystal and battery though, to make sure you don't accidently use them, once you've verified that they're not narrow band.
(What models are they, anyways?)
Oh, the servos you have will almost certainly still work with modern equipment -- they haven't changed.