Category Archives: Radio history

1976 Emergency Power Idea

Fifty years ago this month, the CB column in the March 1976 issue of Popular Electronics carried some pointers for CB’ers to be prepared for emergencies. Included was this simple circuit to ensure that the radio could see uninterrupted service in the event of a power outage.

A trickle charger keeps the 12 volt battery ready to do at all times. And the 4PDT relay ensures that switchover is automatic. (If you can’t find the 4PDT, two DPDT relays would work just as well.)

Edit:  I just noticed that the diagram is wrong.  Can you spot the error?  Post a comment below.



1941 British SWL Station

Shown here 85 years ago this month in the February 1941 issue of Practical Wireless is the receiving station of Ronald Rose of Birmingham, England. At the left is a five-tube superhet, and at the right is a four-tube set. It also includes a wavemeter and speaker.

With a 75 foot inverted L, Rose routinely tuned in stations in America, Australia, and Panama.



1966 Arc Beam Communicator

Sixty years ago, the February 1966 issue of the British Radio Constructor showed a refinement in light beam communication. As we’ve shown previously, it can be done with a normal incandescent bulb. But there were two disadvantages. First, the bandwidth was quite low. And because the light source was spread out along the filament, it wasn’t possible to concentrate the light into an extremely narrow beam.

These problems were solved by the use of an arc lamp, specifically, a Sylvania Concentrated-Arc Lamp type A2, was used. The bulb necessitated a pulse of about 1000 volts, so some additional circuitry is required.  The transmitter is shown here.  The transistorized receiver is typical of other receivers, and is transistorized.

During daylight, the set was said to have a range of at least a quarter mile, and the bandwidth was 1000 Hz.



1956 Code Practice Oscillator

Seventy years ago this month, the February 1956 issue of QST showed this circuit for a very simple code oscillator, using the venerable CK722 transistor. This was actually a simplification of an earlier circuit, which had been updated by George Carson, W0JV.  The oscillator runs on 1.5 volts, but for greater volume, that could be upped to 3 volts.

Carson was a professor at the University of Iowa, and his call is still held by the Iowa City Amateur Radio Club.



1956 British 3 Transistor Portable

Seventy years ago, the British radio enthusiast who wanted to be the first on his block to own a transistor radio could do so, thanks to the plans contained in the February 1956 issue of Radio Constructor.

The portable set, dubbed the “Transistorette,” had been on display at a national radio show, where it had great interest.  As soon as transistors became available in Britain, the editors of the magazine got to work coming up with a practical circuit.  With a short antenna and ground connection, the set provided good loudspeaker volume on the medium wave band.  It was essentially a crystal set, with a three-transistor audio amplifier.  It ran off a 22.5 volt battery, and since transistors were new, the magazine contained a stern warning of the consequences of hooking the battery up with the wrong polarity.



1956 Darb Holiday 3-Way Portable Bike Radio

This cyclist appeared seventy years ago on the cover of the February 1956 issue of Radio Electronics. She is described by the magazine as a “typical Southern university coed,” and she is listening to a favorite program on her Darb Holiday radio, a four-tube portable that could be powered three ways. With separate power packs, it could operate from AC power, 6 volts DC, or dry cells. It featured pushbutton tuning of three preset stations, with no variable tuning.

Another installation by another cyclist is shown at right. The set was manufactured by S.C. Ryan. Co., 1316 Yale Place, Minneapolis.



1941 Two Tube Superhet

Eighty-five years ago, the February 1941 issue of QST carried the plans for this two-tube receiver which covered 1.4 through 14.5 MHz. The construction article, which carried no byline, noted that it was customary for beginners to start with a two-tube regenerative receiver. This one, however, was a superheterodyne. Since it contained no IF amplifier, the detector stage was actually regenerative.

The article conceded that this seemingly combines the disadvantages of both. But this wasn’t really the case. By having the detector set to a fixed frequency, it could be optimized for stability, particularly because the frequency was low, the set using an IF of about 1600 kHz.

The total cost was $11, $1.50 of which was for the most expensive component, the dial. A 45-volt battery supplied the B+, and a filament transformer was used to provide the 6.3 volts. The article noted that both the battery and the transformer could be had for about $2.



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1926 Music Master Model 60

If you were in the market for a radio in Milwaukee a hundred years ago today, you could take home this set from Schuster’s department store for only $69.50, a price which included the set, speaker, batteries, antenna, and tubes. You could be listening right away. The set was a Music Master model 60, and this ad appeared in the February 20, 1926 issue of the Milwaukee Leader.



1941 British Pre-Tuned Two Tube Receiver

Eighty-five years ago this month, the February 1941 issue of Practical Wireless  showed how to build this two-tube receiver . It was specifically designed for use in an air raid shelter from which a reasonable external antenna had been mounted. It could be pre-set to either the Home Service or the Forces program, and once the tuning was set, it needed no further adjustment.

It boasted long battery life for both the filament and high tension batteries. The set could drive a loudspeaker, and the completed project was mounted in the case shown at right.

 



1946 Philco Radio-Phonos

Eighty years ago today, the February 18, 1946, issue of Life magazine carried this ad for two of Philco’s latest offerings.  The model 1213 was a console radio-phonograph.  The ad mentions that the radio tunes both AM and FM (the new postwar band).  But it also covered 9.3 through 14.5 MHz shortwave.

But the model 1201 was revolutionary, having just been invented by Philco engineers.  There was no more fussing with lids, controls, tone arms, or needles.  You simply inserted the record (of any size), closed the cover, and the record would play itself.