Background : Dynatech Cobra SSB CB Radio
I bought this 120 channel Single Side Band(SSB) CB in 1981. I wanted to get into longer distance radio and SSB CB was an easy though not legal way of getting some experience. The correct legal way would be to get a Radio Amateurs Licence and operate on the nearby 28MHz frequency band.
Interestingly this was one of the few models of CB i came across at the time that would not work at all unless the microphone was plugged in. My other unit, the Sharp CB worked perfectly well without the microphone. There was an advantage to this as in the event that you were caught by the authorities if the microphone was not plugged in you could only be listening in to other users and not accused of transmitting which was much more difficult to prosecute and carried a much smaller fine!
Interestingly this was one of the few models of CB i came across at the time that would not work at all unless the microphone was plugged in. My other unit, the Sharp CB worked perfectly well without the microphone. There was an advantage to this as in the event that you were caught by the authorities if the microphone was not plugged in you could only be listening in to other users and not accused of transmitting which was much more difficult to prosecute and carried a much smaller fine!
This picture shows the unit with the top half of the case removed revealing the component side of the circuit board. The channel selector switch and the associated PLL frequency generator IC can be seen at the top left of the photo.
As an Electronic Engineer it was great to get a full circuit diagram with the CB. This was quite common for many products at the time including domestic radios and TV's.
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This photograph shows the solder side of the circuit board. The ribbon cables connecting the circuit board to the front panel controls which can be seen at the bottom of the photograph.
Also supplied was a complete bill of materials of all the components required.
Manufacturers rarely supply this kind of information now as it is so easy for dubious manufacturers to copy the design and sell it as their own. |