Production Year 1966 at $99.95
The Hallicrafters model CB-20 Citizen Band transceiver is a compact, crystal controlled, completely transistorized transceiver that provides up to five channels of operation in the class D citizen band service. The CB-20 incorporates a three stage, transistorized transmitter that is capable of the full Federal Communication Commission(FCC) authorized power limit of 5 watts along with a high level of modulation capabilities. The unit contains a completely transistorized superheterodyne receiver using single conversion. The unit also employs a series type noise limiter to reduce automobile and other local interference. It has an electronic Push-To-Talk(PTT), a high capacity ceramic microphone and a self contained speaker. The CB-20 has 12 transistors, 9 diodes. and one Zener diode voltage regulator.
From the factory, the CB-20 is only supplied for operation on channel 11. Although it is possible for the transceiver to operate on any of the lower 23 channels of the citizen band. In order for it to do so, the unit will need to be disassembled and have additional transmitting and receiving CR-81/U type crystals installed into the provided crystal sockets for the desired frequencies. The CB-20 allows for operation on any five of the lower 23 frequencies or channels of the citizen band. Should crystals be added or replaced for operation on the citizen band channels 1 through 23, no transmitter adjustments should be required. The FCC requires, however, that after the installation of new crystals, the transmitter by checked by a person holding a 1st or 2nd class commercial operators license. The loudspeaker which faces out towards the bottom of the unit is of the permanent magnet moving coil design. Received signals exit through a slotted section on the bottom of the unit. The speaker has an audio output rating of 2 watts. The entire transceiver is housed in a sturdy metal cabinet.
The front panel controls are as follows; starting from the left, an On/Off plus Volume control knob, Channel selector knob, and on the right is a Squelch control. The transmitter section is rated at 5 watts input and has a frequency range of 26.965 MHz to 27.255 MHz. The transmitter has been designed to operate into a 50 ohm load. A Television Interference(TVI) circuit has been incorporated into the transceiver which consists of a bandpass matching network with a 50 DB minimum. The receiver has a sensitivity of less than one microvolt for a 10DB signal and noise to noise ratio.
This transceiver requires a 12 volts negative ground DC power source. When the unit is operated in the receive mode with the squelch open, it draws 3/4 of an amp. When the squelch is applied and there is no sound coming from the speaker in the receive mode, the power consumption drops to 0.07 of an amp. During transmit with maximum modulation the unit draws 1.3 amps.
The physical dimensions are 8 1/2 inches long by 6 inches wide by 2 3/8 inches tall. In the box along with the CB-20 was a mounting bracket, and a separate envelope containing the following items, an FCC license application form 505, an FCC transmitter identification card, a warranty registration card, microphone holder, bracket mounting screws, red lead with fuse holder, black lead, and a perforated rear mounting strap. Optional accessories for the CB-20 included an AC to DC base station power supply and a HA-3 electrical noise suppression kit which eliminated noise that was generated by the automobile that the CB-20 was installed in.
The photograph on the left is a picture of the face of the CB-20. Across the front of the ceramic microphone is a metal sticker with the Hallicrafters name on it. The microphone should be held about one or two inches away from the operators mouth when transmitting. The coiled microphone cable has been wired directly to the circuit board. The CB-20 has been designed with no microphone connector on the outside of the case, thus making the switch to a different microphone an involved task. This was done because of the electronic switching used in the transceiver. Hallicrafters states that it is imperative that only the microphone that was supplied with the unit be used. The electronic switching sequence is as follows; the red and black leads must short before, or at the same instant, but never after the microphone circuit is completed by activation of the PTT switch. Conversely, upon deactivation of the PTT switch, the microphone circuit must open first.
The picture on the right is of the top of the unit. The paper Hallicrafters sticker found here reads as follows....
"NOTICE This equipment is licensed by the Federal Communication Commission, Washington D.C. Tampering with or otherwise molesting this apparatus is punishable by fine or imprisonment or both. The Hallicrafters Company Chicago Illinois".