RE: Narrow banding Question
Dan is right. 72.320 is no longer a legal frequency. That was one of the original 72 mHz frequencies the FCC first granted us for use in R/C in 1966. Only AM transmission was permitted under those rules. The 50 new 72 mHz frequencies that we use now, on which FM is legal, became available in 1991. At that point, the old ones became illegal.
In their day, Cannon made good radios and the company worked hard to reduce sizes and weights of the airborne components to make smaller models more practical. But the R/C world has changed greatly since the 70's and 80's and today's equipment is enormously more advanced than the best of that era and on top of that, today's electronics is also much less expensive than the stuff of a few decades ago so it's hard to justify the expense of putting old radios like that back into service.