[TELECOM Digest Editor's Note: This is an example of how someone > screwed up when the Citizens Band radio channels were numbered. CB is > allocated the space between 26.965 kc and (originally) 27.255 kc. The > 'channels' were 10 kc apart, and there were (originally) 23 channels. > (Well, not originally, when there were 8 channels, but in later > years.) If you look at the difference between 27.255 and 26.965 as > divided in 10 kc increments you get more than 23. That's because the > FCC took three spaces in the middle and reserved them for use on > garage door openers. So we had channel 22 as 27.225 and channel 23 > a full 30 kc later, on 27.255. Then the FCC said they would expand the > CB area all the way up to 27.405, or 40 channels, although common > sense would imply actually 43 channels if you take 27.405 minus 26.965 > at 10 kc increments. What the FCC did, in an effort to 'tidy up' that > discrepany was run the channels slightly out of order. After channel > 22 (27.225) they created channel _24_ at 27.235, channel _25_ at 27.245, > then they had the (already existing) channel _23_ at 27.255 where it > had always been, and then by 10 kc up to channel 40 at 27.405.
There were more than three gaps left in the channels for radio-control. They are at:26.995 (between channels 3 / 4) 27.045 (7 / 8) 27.095 (11/ 12) 27.145 (15 / 16) 27.195 (19 / 20)
then 27.235 and 27.245 as you say, which were later filled by channels24 and 25. In addition, 27.255 was shared between CB channel 23 and the "blue" radio-control channel.
Having those two channels out of order in the frequency allocations > did make for some tricky programming of the 'gang switches' > (revolving knobs which select the channels). PAT]
It also resulted in some interesting switching modifications over here in Britain as well, as when we finally got a legal CB allocation in the early1980s it was just 40 channels running in straight 10kHz steps all the way (27.60125 through 27.99125).
I did quite a lot of EPROM burning to provide UK bands on export sets20-odd years ago.