Letter Re: Radio Basics Presentation


This is in reference to the “Radio Basics Presentation” and the follow-up information from “W.A.

A few points of clarification on a CB myth that just will not go away.

CB radio actually has 40 channels. That’s it; there are just 40 channels.

There are two modes of transmission authorized on CB radio: Amplitude Modulation (AM) and Single Sideband (SSB). On any given channel you can select between the two modes of transmission. You can select AM mode or SSB. With SSB operation, you can select either the Lower Sideband (LSB) or the Upper Sideband (USB) mode. While this gives you the option of three different “modes” per channel, it does not change the fact that there are only 40 channels. When you spin the channel selector knob, regardless of what transmission mode you have selected, you still only see 40 channels on the display.

These 40 channels must be shared by everyone. AM and SSB signals do not mix. For practical purposes, there can only be one conversation on a channel at the same time. You cannot have two persons talking on AM mode, two persons talking on LSB, and two more persons talking on USB, all trying to use the same channel. It just doesn’t work.

CB radio manufacturers have used the sales pitch of “120 channels” in their advertising for years. And that’s all it is, a sales pitch or gimmick that falsely gives the impression that SSB operation gives you more channels. It doesn’t. There are only 40 channels.

Another sales gimmick: for years Radio Shack claimed their CB radios had “5-watts of power”. They don’t. Back when there were only 23 channels authorized for CB radio, the FCC regulations specified the output power could not exceed “5-watts input to the final amplifier stage”. This was a common measurement associated with tube-type radio equipment. When measured at the output connector on the back of the radio, most “5-watt input” CB radios had an actual output power of 3.5 to 3.8 watts.

When the FCC authorized 40 channels, it also updated the regulations to match the solid-state radios that had become the norm. The “5-watt input” regulation was changed to the far simpler “4-watt output” standard. But for years, Radio Shack continued to advertise their CB radios as having “5-watts”. The ads were careful not to mention “output power”, since that would imply violation of the FCC regulations. The Radio Shack CB radios all put out the maximum of 4-watts output power. The mention of “5-watts” was just advertising hype.

I also recall seeing a Midland CB radio advertised as having “7-watts of power!*”. But if you followed the asterisk down to the fine print, you saw that statement was clarified as “7-watts of audio power to the speaker”. While the extra audio power to the speaker might be helpful in a noisy truck cab, it has absolutely nothing to do with RF output power to the antenna. Again, it was just advertising hype. Buyer beware!

Since AM and SSB signals don’t mix well on the same channel, it is important to know where the SSB’ers hang out. After the 40 channels were authorized by the FCC, the SSB’ers moved up to Channels 36-40. Channel 36 LSB became the “calling channel” to monitor when attempting to make a SSB contact. Once contact was established, the conversation was often moved to Channels 37-40. AM operators who wandered onto one of the top five channels were often told bluntly that they were on a “SSB only” channel. This “gentleman’s agreement” limited the SSB operators to five channels, leaving the remaining 35 channels to the AM operators. Considering the far greater output power authorized for SSB operation, it was to the benefit of the AM operators to let the SSB operators have their five channels to operate on.

Another point of clarification: the 40 channels from 26.965 to 27.405 MHz are the ONLY authorized CB channels. Anything else is illegal. In like fashion, the authorized RF output power levels are 4-watts for AM radios and 12 watts Peak Envelope Power (PEP) for SSB radios. Anything above those levels is illegal.

The 40 CB channels can be crowded. There are a lot of folks sharing the same channels. It is similar to being in a crowded sports stadium packed with fans. The noise level can be deafening. However, with the crowd comes a degree of anonymity. It can be difficult for an eavesdropper to pick out your conversation with your buddy from all the other conversations going on. There is safety in numbers, especially if you blend in with the crowd and avoid drawing attention to yourself.

It therefore baffles me that there are so many people who like to run outrageous output power levels far in excess of the legal limits. Or they are fascinated by “freeband” operation on illegal channels below Channel 1 or above Channel 40. They use modified CB or Ham radios, or purchase “Export” CB radio models. The advertising for “Export” CB radio models hint that they are legal to own somewhere, as long as they are exported to that location. However, the fact is that “Export” CB radio models have a combination of channels, modes, power output, and other features that make them illegal in every single country in the world. There is no place on earth where they may be legally used.

What these people fail to realize is that by their actions they have left the crowded sports stadium and the anonymity of the crowd. They are now outside the stadium in a huge open field, wearing a red t-shirt and waving a red flag. They are easy to spot and to identify. A sweep of the radio spectrum above and below the 40 CB channels, using a shortwave receiver or spectrum analyzer, will quickly reveal their signals. Using excessive output power will really make the signal stand out. The concepts of OPSEC and maintaining a low profile have been completely eliminated. Your signal stands out like a nail sticking up from a board. Those are the very same nails that get hammered. If you want to survive WTSHF, you had better learn to not stick out. Don’t make it easy for the government monitoring stations to find you by operating out of band or with high power. Learn to blend in with the crowd. There is safety in numbers. – 73 de Sarge