The earliest portable radio was the most portable ever made, the lightest, the least expensive and completely solid state. And this was almost 60 years ago. It consisted of a galena crystal detector mounted on a necktie stickpin and had four connections, for antenna, ground and headphones.
It required no batteries, could work forever, had no moving parts except for the detector. It had its problems, though. It picked up all broadcasting stations but could not separate them and its sound volume was barely noticeable.
When vacuum tubes came along the popular approach was "the bigger the better." Portables were the "in thing" in the thirties, but since they were battery operated, they demanded a strong back. The batteries alone, and each portable needed three different types, weighed much more than about a dozen modern units. These portables were popular for beach use, but to prevent physical exhaustion had to be carried there in a car.
The solid state semiconductor transistor changed all that. Capable of being powered by tiny batteries and of delivering loudspeaker volume, transistors revolutionized the portable receiver. They were made so small they fit easily into shirt pockets or dangled by a chain from the wrist. Some could be worn like wrist watches.
Early portables were AM only. FM became possible by making the circuits do double duty. For AM reception a built-in loopstick antenna is used; for FM, a telescoping antenna which recesses into the case of the portable.
When cassettes showed they had music reproducing abilities, the portable became the popular unit it is today. The portable became more functional and it wasn't too long before short wave bands were added. All this meant price increases, so today it's possible to buy a portable for as little as $10, or several hundred.
The $10 and under portable sounds too cheap to be any good, but at one time the cost of a single transistor in these radios sold for much more. Mass production and low labor cost in Hong Kong and Taiwan has brought these down to where they are highly affordable. They cover only the AM band but they have a tuning control, combined on-off switch volume control, and a lightweight "in your ear" headphone is supplied. The battery is a single 9-volt type and the overall weight, with battery, is 10 ounces or less. Many portables, including the least expensive, are supplied with a wire type built-in metal stand so they can be put in a tilted position.
The name of the portable game is features, but these bring up the cost. The first of these is the two-band unit, covering both AM and FM; it has a carrying strap and a rear mounted switch for selecting AM or FM, a telescoping antenna and a jack for an in-the-ear headphone. It's possible to pick up stereo FM stations but these portables are designed for mono only, and have just a single small speaker. The power source is a single 9-volt battery. Total weight, including the battery, is about 10 ounces.
Portables can be quite sophisticated. One unit is not only AM/FM but is equipped with a liquid crystal diode (LCD) digital clock. A separate lithium battery with a service life of one year is used for the clock and three AA pen-light batteries for the radio. The clock is equipped with a beep wake-up alarm that will run for about four minutes after the selected alarm time has been reached and it will then turn off automatically. Unlike analog clocks, the digital in the radio has an AM and PM indicator. The clock has an hour switch, minute and second display switches.
Some of the larger portables are designed for stereo FM and use a pair of 4" to 6" speakers. But because the speakers are separated by a few inches, all sound, whether stereo or not, will be heard in mono only.
The sound quality of portables is nothing to get excited about. Many of them distort seriously, particularly when the volume control is advanced. There is less distortion with headphone listening since less sound power is required.
Portables with a built-in cassette tape facility are heavier and larger than the AM only or the AM/FM types and weigh about 4 lbs. including the batteries, usually four size C cells. In some portables the cassette is for playback only and these are less expensive than those that have a playback/record facility. Those that can record have a condenser microphone built into the case. An interesting feature is that these units generally have a tone control, not found in less expensive portables. The cassette tape section is operated by switches, either plano keys or pushbuttons. The cassette section includes fast forward, play, rewind, record and a button that is a combined stop and cassette eject.
With a portable of this kind it is possible to take along cassettes recorded at home, or commercially prerecorded cassettes, and to record any external voices or sounds. portables are also available that are cassette recorder/players only, but aren't radios.
Portables now range from a few ounces in weight to a few pounds or more. Size, weight, features, styling--all of these affect the cost. But no portable manufacturer emphasizes sound quality--or its lack.
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