Radio Comparison: Vacuum Tube Radio vs Transistor Radio

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Author: Kynix

Published: 2021-11-03 | Last Updated: 2021-11-03

Contents

Introduction

In general, the radio is constructed by mechanical devices, electronic devices, magnets, etc. It receives the audio signals emitted by broadcasting stations through converting electric wave signals. After the invention of the vacuum tube, the circuit and receiving performance of the radio had undergone revolutionary progress and improvement, that is valve radio. Later, with the development of technology, radios with transistors as the core gradually became popular. It's what we know as a transistor radio. Radios are still widely used for many functions. Here two main radios will be described in detail below.

Catalog

Introduction

Ⅰ Valve Tube Radio

1.1 Vacuum Tube Radio Classifications

1.2 Advantages and Disadvantages of Valve Radio

1.3 German Vintage Valve Radio Models for Sale

Ⅱ Transistor Radio

2.1 Transistor Radio Overview

2.2 Transistor Radio Selection Matters

2.3 Transistor Radio Brands for Sale

Ⅲ Radio Further Development

Ⅳ FAQ

Ⅰ Valve Tube Radio

The valve radio, also known as the vacuum tube radio, was a product of the early 20th century, and immediately became the new favorite of that era with the launch of the broadcasting station. By the late 1920s, vacuum tube radio equipment replaced the primitive spark-gap systems on most merchant ships. This new equipment could send and receive signals virtually worldwide, by using high frequency or "short-wave" bands. Tube technology allowed radio signals to be tuned with much greater precision than spark-gap. The basic design for tube radio was perfected by the 1930s and continued in use on merchant vessels into the 1980s.

1.1 Vacuum Tube Radio Classifications

🔺AM (Amplitude Modulation) Radio
In the era when tube radios were popular, AM radios were the mainstream products. Amplitude modulation wave modulates the high-frequency carrier with audio signal. Its waveform is symmetrical, the amplitude is the same as that of the modulated signal, and then obtain the audio signal after high-frequency component is filtered out. In addition, the frequency of the carrier signal (the frequency of the broadcasting station) is the carrier frequency.
AM radios can receive medium-wave and short-wave broadcasts, and some can receive long-wave broadcasts. Since the mid-band frequency interval has been unified to 9KHz, its highest audio frequency is only 4KHz. So the sound quality is affected because of large electromagnetic interference.
There are two main types of AM radios: direct-amplifier type and external (self) differential type
1) Direct-amp radio, also called high-amp radio, its typical circuit structure is as follows:
High Amplifier—Detection—Low Amplifier—Power Amplifier
A circuit that uses a grid detector circuit and high-frequency positive feedback is called a regenerative radio, which can obtain higher sensitivity and amplitude selectivity. A regenerative radio with high amplifier and short wave can receive AM telegraph signals. Most of the old Japanese-made radios have such circuits. Direct-amp radios are prone to self-excitation of high-frequency signals, high-end and low-end gains are uneven, and regenerative radios without high-amplification have poor selectivity. In addition, the reed speakers with poor sound quality are generally used, so they are gradually replaced by superheterodyne radios.
Simple regenerative radios mostly use reed speakers, which have high impedance (about 10K) and high sensitivity. It can be directly used as the load of the power amplifier tube, but the frequency range is only 350~3000Hz, so the sound quality is poor. Later regenerative radios applied moving coil speakers, and the sound quality was better. However, because of low impedance, an output transformer is required, and its primary impedance must match the load impedance of the power amplifier tube. Moving coil speakers are divided into permanent magnets, constant magnets and excitation. Among them, excitation horns are used in AC electronic tube radios, and their excitation coils can also be used as filter chokes.

2) Heterodyne Radio
The heterodyne radio adopts a frequency conversion circuit. The signal generated by its high-frequency oscillation circuit and the input signal have a certain frequency difference. After the two are mixed, a fixed intermediate frequency signal (455~465KHz) is generated. Some people call the oscillation frequency higher than the signal frequency a heterodyne type, and vice versa.
Heterodyne plus intermediate frequency amplifier circuit is called superheterodyne. This type of circuit requires a single electron tube to oscillate, and later a multi-pole or composite tube dedicated to frequency conversion appears. The superheterodyne type is the most common circuit of commercial radios. It has an automatic volume control circuit and can add tuning instructions. The circuit principle will be described in detail later. The superheterodyne radio can obtain more stable and higher gain due to amplifying the fixed frequency. The disadvantage is that there is image frequency interference.
The circuit structure of a typical superheterodyne radio is as follows:
Frequency Conversion—Middle Amplification—Detection—Low Amplification—Power Amplification

3) Autodyne Frequency Conversion Radio
Using ordinary pentodes for frequency conversion is only suitable for the mid-band, and the middle frequency is 175KHz. Due to the popularization of special frequency conversion tubes, it is rarely used now.

Vintage AM Radio

Figure 1. Vintage AM Radio

🔺FM (Frequency Modulation) Radio
FM radio is a radio that transmits radio signals through the use of FM frequency modulation carrier. Due to the shorter wavelength, the signal transmitted is much better than that of the radio that uses the AM wavelength. However, due to the short wave, the transmission distance is relatively short.
FM wave is to use audio signal to modulate the frequency of high frequency carrier. Its advantages include strong anti-interference ability, high signal-to-noise ratio, good frequency bandwidth and sound quality, in addition, the audio frequency can reach 20Hz~15000Hz. Because the FM wave works in the ultra-high frequency band, it can accommodate many radio stations. With its linear propagation characteristics, the same frequency can be reused at a distance of hundreds of kilometers, which can effectively solve the problem of congestion of medium and short wave radio stations.
Modern FM broadcasting is compatible with stereo and mono channels(in the early days of stereo broadcasting, two frequencies were used and two radios for reception). Some hobbyists are likely to use a simple super-regenerative circuit to receive FM broadcasts. Because it works in a self-oscillation state, the work is unstable and has strong super-noise.

1.2 Advantages and Disadvantages of Valve Radio

Advantages of Valve Radio

1) The valve tube circuit has a simple structure and good anti-overload performance.
2) The characteristics of the power amplifier circuit of the tube radio are better than those of the transistor or integrated circuit power amplifier. The screen current of the Class A power amplifier circuit with an output transformer for output impedance matching has little change at zero signal and full signal. So the performance is stable, the distortion of the line work area is very small, and the harmonic content is very rich .
3) The speakers used in valve radios are generally larger in diameter than those of transistor or integrated circuit radios.
4) The IF circuit characteristics of tube radios are better than those of transistor or integrated circuit radios.
5) Have collection value.

Disadvantages of Valve Radio

As for the shortcomings, valve tubes that are large in size and used as basic components, built-in accessories are also bulky, power consumption has also increased, the overall quality has become poor, inconvenient to carry, and poor seismic performance. In addition, it is very difficult to make FM stereo radio devices, because early tube radios can only receive shortwave and medium waves. These shortcomings eventually led to the replacement of tube radios by transistor radios.

Vintage Valve Radios - Will they work?

1.3 German Vintage Valve Radio Models for Sale

AEG Radio
Blaupunkt
German EMUD
Graetz Vintage Radio
Grundig Vintage Radio
Hornyphon Vintage Radio
Vintage Koerting Radio
German Metz Vintage Radio
Vintage Nordmende Radio
Philips Vintage Radio
Vintage Saba Radio
Vintage Siemens Radio
Telefunken Radio

Vintage Valve Radio

Figure 2. Vintage Valve Radio

Ⅱ Transistor Radio

2.1 Transistor Radio Overview

The transistor radio is the second generation radio after the valve radio. Compared with vacuum tubes, transistors are small in size, light in weight, resistant to vibration, long in life, and low in power consumption. This kind of radios can be made compact and have relatively stable performance. Therefore, after the advent of transistor radios, a large number of portable radios and pocket radios have emerged. They are very convenient for daily use. The Regency TR-1 was the first commercially manufactured transistor radio by developed by Texas Instruments and IDEA Inc., introduced in 1954.
Transistor radios use transistors to process and amplify signals. Simple to use, it is a small transistor-based radio receiver.

2.2 Transistor Radio Selection Matters

To choose a good transistor radio, you must first understand four basic relationships:
1) The larger the chassis volume, the better the sound quality.
2) The larger the horn diameter, the better the sound quality.
3) The larger the battery volume, the longer the relative service life of the battery.
4) The longer the magnetic bar, the higher the sensitivity.
Secondly, we should also pay attention to five points when selecting:
1) The change after the power supply voltage is reduced should be small. When selecting, you can have listening trial, because the impact on a high-quality radio should not be significant.
2) The distortion of the offset radio should be small. After finding a radio station, having the left and right adjustments, the distortion should be small. In addition, there should be no whistling sound, otherwise, the frequency characteristics of the intermediate frequency part are poor.
3) The volume change should be small when turning the button.
4) Human body induction has little influence. When a person's body is close to the radio, it will have a certain impact on the work of the radio. This situation is particularly obvious for shortwave.
5) The noise should be small. Noise generally includes electrical noise and mechanical noise. Turn the radio to a place where there is no station, and turn on the volume to the maximum. At this time, the minimum sound is better. Listen to a program to check whether there are noises caused by resonance of certain components when the volume is loud. Finally, you should also pay attention to whether the tuning knobs and buttons are coordinated and effective, and whether the shell of the radio is damaged or not.

Vintage Transistor Radios Show And Tell

2.3 Transistor Radio Brands for Sale

Edifier
GAORUI HOME TEXTILE
SONY
Rolton
HALFSUN
Panda
Soaiy
Nintaus

Regency tr-1 Transistor Radio

Figure 3. Regency tr-1 Transistor Radio

Ⅲ Radio Further Development

With the advent and development of integrated circuits, transistors have been replaced by integrated circuits, that is the third-generation radios invention, sometimes also known as semiconductor radios.
After the radio uses integrated circuits, not only the size can be made smaller, but also the reliability is high. As the number of integrated circuit components is getting larger and larger, radios made with it have better performance and more functions. The integration of radios has become an inevitable trend.

Ⅳ FAQ

1. What is a vacuum tube radio?
A vacuum tube, also called a valve in British English, is an electronic device used in many older model radios, television sets, and amplifiers to control electric current flow. The cathode is heated, as in a light bulb, so it will emit electrons. ... The anode is the part that accepts the emitted electrons.

2. Do valve radios still work?
A valve radio will never be as reliable as a transistor set, and short of ripping out the chassis and replacing it with a transistor circuit, we aren't going to make it that reliable. However, some designs of valve set are more unreliable than others, and the main factor seems to be heat.

3. What did valves do in radios?
The valve was useful as an electronic switch and its first use was in radio circuits detecting signals. The valve has two elements - a wire and a metal plate surrounded by a vacuum. The electricity flows between them.

4. How does a tube radio work?
The basic working principle of a vacuum tube is a phenomenon called thermionic emission. It works like this: you heat up a metal, and the thermal energy knocks some electrons loose.

5. When did radios stop using vacuum tubes?
1950s-60s - Most vacuum tubes were replaced by transistors in the west. 1970s-80s Tubes are still used in many specialized applications like broadcast television and radio.

6. Why did we stop using vacuum tubes?
Vacuum tubes suffered a slow death during the 1950s and '60s thanks to the invention of the transistor—specifically, the ability to mass-produce transistors by chemically engraving, or etching, pieces of silicon. Transistors were smaller, cheaper, and longer lasting.
A transistor is a semiconductor device used in electronic circuits as to function as "on" and "off" switching and amplifying device in the electronic circuits. ... Radio is a device which transmit and amplifies signals. The modern radio uses transistor since it is smaller in size.

7. Are transistor radios still being made?
Transistor radio is an obsolete term now, carried over from when having transistors rather than tubes made small radios possible. It has come to be analogous to a portable, battery-powered radio, so while I will be making some recommendations, they likely will have integrated circuits, rather than transistors.
It is a radio receiver which uses transistors to amplify the sound. Transistor radios can be cheap and small and some use very little electric power. Some can amplify the weak radio waves that are usually not picked up by weaker vacuum tube radios.

8. What does a transistor radio do?
The function of transistors in radios is straightforward. Sounds are recorded through a microphone and turned into electrical signals. Those signals travel through a circuit, and the transistor amplifies the signal, which is subsequently much louder when it reaches a speaker.

9. Why was the transistor radio invented?
One goal was to find a replacement for fragile and energy-wasting vacuum tubes. Building on war-time research, John Bardeen and Walter Brattain, working with group leader William Shockley, developed a device they called a transistor.

10. Where was the transistor radio invented?
There was a tremendous push during the war to reduce the size and power consumption of vacuum tubes, particularly because the receivers used in radio-controlled bombs depended on vacuum tube technology. “Not long after the war ended, the transistor was developed at Bell Labs, in 1947.

11. What is the name of first transistor radio?
Regency TR-1
In July 1954 the Texas Instruments and Industrial Development Engineering Associates (I.D.E.A.) companies embarked on a six month project to produce a pocket-sized radio for the Christmas market. The result was the Regency TR-1, the world's first pocket transistor radio.

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Radio Comparison: Vacuum Tube Radio vs Transistor Radio

Introduction

Catalog