CBWI December 1996 Clarifiers
You may wonder why CBs are locked on frequency. Back when sideband was first introduced to the CB community, The clarifiers would move both transmit and receive together. This was legal because the tolerance of the transmitters was +/- .005 %. This means the radio had a frequency range of +/- 1.3 kHz from the center frequency.
The industry used this leeway for the clarifier. They also designed the circuits to be modifiable to increase this range substantially. Back in those days, everyone wanted to go down 10 kHz to make use of the RC or “A” channels. They used 3A, 7A, 11A, 15A, and 19A for sideband to get away from the congestion of channel 16 or whatever happened to be the local sideband channel.
When the “A” channels were busy operators dropped 5 KHz to make use of other unused space between 15A and 16. This activity upset the FCC and when they approved additional channels new stringent regulations were imposed including the one that mandates all transmitters must be locked on frequency. This made anything more than a two-person conversation difficult.
Radios were off frequency and any third party sandbagger would go nuts turning the clarifier back and forth. Everyone wonders why the factories let radios out that are off frequency. By the letter of the law, they’re not. The new tolerance is +/- .002% giving them a leeway of just over +/- 500 Hz and still be considered on frequency. In production, the radios are set before having time to reach full operating temperature.
This is one reason for new radios being off frequency out of the box. Uncle Charlie’s actions made it necessary for most operators that wanted to use sideband to contact a technician and while at the shop they’re usually told about extra channels and so on. The customer most often decides to get everything done at one time.
Charlie’s plans backfire again! All sideband clarifiers can be unlocked and expanded to a degree. Some, like the Cobra 148GTL and 200OGTL will slide +5 KHz and -12 KHz without changing parts or adding chokes. Although it’s nice to have capabilities to go anywhere, the more range a clarifier covers the more touchy it is to use. ©CBWI