ORIGINAL: Jim Schwagle
I remember following a thread similar to this a year or more ago, with many people far more knowledgeable than I contributing, and the conclusion was that the modification (I'm not advocating swapping crystals) ban did not apply to 27 MHz. A quick search of the FCC site shows that the ban (95.222) applies to type-accepted transmitters(95.209 refers to 95.222 and specifically mentions type accepted transmitters), and the 27MHz band, is non type-accepted as per 95.209. This rule does refer to technical specifications I did not look up. I'll just stick to 72 & 75MHz with synthesized transmitters and receivers to solve my problem. I guess that since the park flyers tend to be lower cost, manufacturers just don't pay attention to 27MHz with regards to more sophisticated transmitters.
Jim I beleve your assesment is reasonably accurate and for whats it worth the 1991 narrow banding in the US did not apply to our six channels on the 27Mhz band either. This has allowed a flouishing market in very old systems on the band that predate the middleaged wideband systems on 72 that are illegal. This for the challange flying vintage RC airplanes (not RC assist old timer free flights) as it once was. Of course great care is taken in when and where they are operated due to shareing with surface RC and garage doors.
John