An antique radio is a radio receiving set that is collectible because of its age and uniqueness. Although collectors may differ on the cutoff dates, most would use 50 years old, or the pre-World War II Era, for vacuum tube sets and the first five years of transistor sets.
Types of antique radio
Morse only sets
The first radio receivers used a coherer and sounding board, and were only able to receive morse code, and thump it out on the board. This type of transmission is called CW (Continuous wave) or wireless telegraphy. When wireless telephony (ie transmission & reception of speech) became possible, speech radio greatly improved the usability of radio communication. Despite this, the antiquated technology of morse code transmission continued to play an essential role in radio comms until the 1990s.
All other sections of this article concern speech capable radio, or wireless telephony.
Early home made sets
The idea of radio as entertainment took off in 1920, and radio ownership steadily gained in popularity as the years passed. Radio sets from before 1920 are rarities.
Pre-war sets were usually made on wooden breadboards, in small cupboard style cabinets, or sometimes on an open sheet metal chassis. Homemade sets remained a strong sector of radio production until after the war. Until then there were more homemade sets in use than commercial sets.
Early sets used any of the following technologies:
Crystal set
Crystal set with carbon or mechanical amplifier
Basic TRF
TRF Reaction Sets
Super-Regenerative Receiver
Superhet
Crystal sets
These basic radios used no battery, had no amplification and could only operate headphones. They would only receive very strong signals from a local station. They were popular among the less wealthy due to their low build cost and zero run cost. Crystal sets had minimal ability to separate stations, and where more than one high power station was present, inability to receive one without the other was a common problem.
Some crystal sets users added a carbon amplifier or a mechanical turntable amplifier to give enough output to operate a speaker. Some even used a flame amplifier.
TRF
TRF sets (Tuned Radio Frequency) are the most popular class of early radio. These used one or more valves (tubes) to provide amplification. Early TRF sets only operated headphones, but by the 1930s it was more common to use additional amplification to power a loudspeaker, despite the expense.
The types of speakers in use at the time were crude by today's standards, and the sound quality produced from the speakers used on such sets is sometimes described as torturous. Speakers widely used on TRF sets included:
moving iron horn speakers
moving iron cone speakers
tin can, magnet & wire based speakers
in a few cases a moving coil speaker
The above are not altogether clear distinct categories, with significant overlap, nor a complete list, but represent the technologies in popular use.
Earliest TRF sets used no regeneration, and had very poor rf sensitivity and low selectivity. Thus only nearby stations and strong distant stations would be received, and separating different stations was not always possible.
Most TRF sets were reaction sets, aka regenerative receivers. These rely on positive feedback to achieve adequate gain. This approach worked well enough, but is inherently unstable, and was prone to various problems. Consequently there was a significant amount of hostility over maladjusted radios transmitting squealing noises and blocking reception on nearby properties.
TRF sets had typically 2 tuning knobs and a reaction adjustment, all of which had to be set correctly to receive a station. Earlier reaction sets also had filament adjustment rheostats for each valve, and again settings had to be right to achieve reception.
Superhets
In this era of early radio, only the wealthy could afford to build a superhet. Such sets required many valves and numerous components, and building one was a sizeable project.
Pre-war superhets were often used with the relatively expensive moving coil speakers, which offer a quality of sound unavailable from moving iron speakers.
Most post-war commercial radios were superhets, and this technology is still in widespread use in consumer radios today, albeit implemented with transistors and integrated circuits.
The advantages of superhets are:
Excellent sensitivity, enabling reception of foreign broadcasts
Complete stability
Well controlled bandwidth
Well shaped rf passband avoids the uncontrolled tone variations of TRF sets, and gives good selectivity
The downsides for pre-war superhets were:
Very high build cost
High run cost due to many valves and the need for large high power batteries
Construction was a sizeable project
Foxhole radios
World War 2 created widespread urgent need for radio communication, and foxhole sets were built by people without access to traditional radio parts. A foxhole radio is an illegally constructed set from whatever parts one could make, which were very few indeed. Such a set typically used lighting flex for an aerial, a razor blade for a detector, and a tin can, magnet and some wire for an earpiece. I.e. they were crude crystal sets.
Wooden consoles
The console radio was the center piece of every house back in the era of radio, they were big and expensive running up to $700 back in the late 1930s. Mostly for the wealthy, these radios were placed in hallways and living rooms. Most console radios were waist high and not very wide, as the years went on they got shorter and wider. Most consumer console radios were made by RCA, Philco, General Electric, Montgomery Ward (under the Airline brand name), Sears (under the Silvertone brand name), Westinghouse, radio-bar and many more. Brands such as Zenith, Scott, Atwater-Kent, were mainly for the rich as their prices ran into the $500-$800 range in the 1930s and 1940s.
Panel Mounted Control Switches
Knob Adjustment Vacuum Switches
Fast Replacement Limit Switches
automobile alternator power output
MC-36 Multi-Function Remote Cord
Variable Height Plunger Switches
没有评论:
发表评论