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The Rise and Popularity of Plastic
The Rise and Popularity of Plastic
Majestic 5T10 (1942) Popular Bakelite Radio
The Rise and Popularity of Plastic in Radio Cabinets. Wood cabinets are labor intensive. The introduction of plastic materials allowed cabinets to be molded, saving labor costs. Early plastics used a material called bakelite, which was hard and overtime became brittle plus it came in a dark brown so sets had to be painted if a particular color was wanted (usually white). Plaskon was a popular product that made radio cabinets lighter and thinner. White or ivory were the standard colors.The other was CATALIN which allowed colors to be added during molding process. Like Plaskon it was a fairly lightweight material. Today CATALIN cabinet radios are highly sought after and expensive.
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Plastic Table Radios
Plastic Table Radios
Plastic gave new meaning to small stylish radios. A manufacturer could cheapen the design to save money, yet make a good profit because the look and style is the selling point. These plastic sets became the stepping stone of what was to come.
Zenith 6D312 "Beehive" (1938). Zenith Radio Corp, Chicago IL. Bakelite with push button tuning.Highly collectible today. . Uses 6A8G, 6K7G, 6Q7G, 25L6G, 25Z6G and 100-70 Ballast Tube. Transformerless pre AA5 radio.
UPDATE: Updated restoration was done in 8/2014. This involved adding a missing tube shield, added another over 6A8G tube for better stability, stuffed new capacitors into paper capacitor body, rechecked resistors, made a back cover similar to the original.
Zenith 6D315 (1938) Zenith Radio Corp, Chicago IL. A low end Zenith Bakelite that is highly collectible today. Uses 6A8G, 6K7G, 6Q7G, 25L6G, 25Z6G and 100-70 Ballast Tube. Transformerless pre AA5 radio.
BELOW: The black metal tube is a ballast. Inside a ballast is one or more wire resistors used to drop voltages (usually the tube heaters not adding up to the line voltage). They were also a sales tool, tauting more tubes- better set. Notice the speaker has been replaced with a permanent magnet speaker. The original field coil is mounted above the speaker.
Metal cover removed to see inside the 100-70 ballast tube
Majestic 5T10 (1942) Made by Grigsby-Grunow Chicago IL. AA5 radio using all glass GT tube version (12SA7GT, 12SK7GT, 12SQ7GT, 50L6GT and 35Z5GT). The cabinet style like a football. Majestic used this design into the post war period.
Dial Light
Typical pre war AA5 circuit. Most AA5 tube complement would have three metal tubes (12SA7, 12SK7, and 12SQ7). All glass GT style tubes are used. Very roomy chassis compared with other sets.
6D312 Totally Restored
BELOW: Emerson BJ200 Cabinet is like a kit. The bakelite cabinet consists of three parts that slide into each other around the electronics. To make repairs or change tubes one has to disassemble the cabinet.
BJ200 Dial Light
Dial glow of Ward's Airline 24BR-735B.
Back side of Ward's Airline 24BR-735B.
Sears Silvertone 6102A Midget Bakelite Radio. Has 4 tubes operating as a TRF RADIO. Uses 12Z3 rectifier, 25L6G Power Amp, 6F5 amplifier and detector and 6D6 tubes for the RF stages. Price in 1938 was $9.95.
Emerson BJ 200 (1938) Emerson Radio Corp, New York, NY. Transformerless Table Radio. (1938 compact using a new type of plastic called bakelite). AM/SW 6 Tube Superheterodyne. Uses 6A7, 6C6, 6Q7G, 25L6G, 25Z5 and L49 Ballast. Ballast tubes are wire resistors used for voltage dropping. In this case a ballast is to drop the remaining line voltage for the tube heater string. Transformerless pre AA5 radio.
Top of chassis. Notice the black metal tube, that's the L49 Ballast tube. The Emerson is cross between the older prong pin vacuum tubes and the newer octal based tubes. The Emerson used the wet electrolytics (the two aluminum cylinders) which were by this time being replaced with more compact dry paste types.
BELOW: Complete restoration of the BJ200. Had to do a lot of redressing of the wire and the pathways. Was pretty sloppy assembly.
Ward's Airline 24BR-735B (1942) Made by Belmont Radio (Equiv to model 7D21 and 7D22 Series B))
Painted Bakelite with Pushbutton Tuning. One of the last prewar radios. Interesting Transformerless 7 tube AM/SW Radio. Incorporates separate oscillator (12J5GT) and Converter (12SF7) which provides wider band tuning and more transfer gain.
Painted Bakelite with Pushbutton Tuning. One of the last prewar radios. Interesting Transformerless 7 tube AM/SW Radio. Incorporates separate oscillator (12J5GT) and Converter (12SF7) which provides wider band tuning and more transfer gain.
ABOVE: Clean off chassis. I had to sand off the rust. The 6D6 tube does tend to oscillate, The tube shields were missing. BELOW: Complete restoration, The capacitors were cleaned out and stuffed with new ones while some resistors were too high value so adding a resistor in parallel brought the value close to specified amount.
BELOW: The radio originally used a line cord resistor to drop 60 volts along the heater string. Unfortunately, a 195-ohm 18 watts resistor is needed. I used a Dale-Vishay 200 ohm aluminized 25-watt resistor and gets pretty hot. To dissipate the heat, I mounted it to the chassis.
LEFT: Back side has large vents. You can see the tubes glow.
Plastic and Other MIDGET Radios
Plastic and Other MIDGET Radios
Often sold as an extra set around the house. Midget sets began during the early Depression when manufacturers had to cut cost to sell radio sets. They later became the extra set or that bargain set for those who live in the metro areas. Usually sells between $7-$12, They were minimal sets often low end TRF sets or bare bones superhets. The use of plastic help open up the market for these sets. All midgets were transformerless. Early models used "line cord" resistors that look like a basic AC power cord, but these had a third resistive wire to help drop the tube filament voltage. These cords got warm to the touch.
Tuned Radio Frequency (TRF) Sets
Sonora TK or TP (1939-40) Sonora Radio, New York, NY. Price was less than $8, MIDGET Uses 4 Tubes (12K7-GT, 12J7-GT, 35Z5GT and 50L6GT)
TRF sets are sensitive but are not very selective. Strong signals tend to "drown out" the tuning. Bakelite cabinet. Later midgets started using Plaskon material, which provided more variety of shapes and lines but were prone to heat cracks and deformations.
TRF sets are sensitive but are not very selective. Strong signals tend to "drown out" the tuning. Bakelite cabinet. Later midgets started using Plaskon material, which provided more variety of shapes and lines but were prone to heat cracks and deformations.
Very small (5" H X 7" W X 4.5" D)
Very Crowded. Layout before restoration.
Replace Capacitors. Modern parts free up a lot of space.
ARVIN Metal Midget Radios
In 1938, Noblitt-Sparks (Arvin) decided to take a different path and produced midget sets with metal cabinets. Turned out to be a successful product line as they continued the product into the early 1950s.The first was the model 40 (1938-39) it used two tubes a 25B8GT and 70L7GT. These two tubes did the job of 4 tubes. Soon after came the model 402 (1940-41) that used three tubes, a 25B8GT, 50L6GT and 35Z4GT or 35Z5GT, that did the job of 4 tubes. The final configuration that was used into the 1950s was the 422 (1941-42) that used the AA4 set 12SA7, 12SQ7, 35Z5GT and 50L6GT. The AA4 was adopted probably for cost savings as the other tubes like the 70L7GT and 25B8GT were not as common and probably cost more.
Arvin 422 and 422A (late 1941-42) Price was $6.95. Measuring only 6.5 inches wide, was definitely one of the smallest midget sets. Features a superheterodyne circuit using 4 tubes (12SA7, 12SQ7, 50L6GT and 35Z4GT or 35Z5GT).
The dial face is a reproduction of a Arvin 444 midget produced for 1942 year. The original foil dial was missing. The dial has the same dimensions; the graphics is slightly different.
ABOVE: only one IF transformer and 4 tubes. Comes with 30 ft of antenna to provide local reception. BELOW: complete restoration, hiding most modern components in or near vintage parts.
Plastics made the compact radio very small. Sometimes half the size of wood compacts. Problem the plastic tends to deform with heat from the tubes so very few survive to collectors. They were throw away radios.
Above: TSA-155 front view and with panel light on.
Above NOT MUCH SPACE, expect a HOT cabinet radio. That's one of the reasons why midget radios are relatively rare to find one without cracks or find one at all.
Above: Compare underneath the chassis of the Emerson CL-256 with the Sonora TK on the LEFT. The Emerson is only about inch wider but has FIVE tubes.
BELOW: Front face of the RCA 5X5. Notice the long crack on the left side. That was the condition of the set when I got it. It has been securely repaired but you can never get it back the way it was. Usually damaged sets don't have much collecting value. But sets like this one are hard to come by, so often it is worth picking up cheap.
Dial light,
Superheterodyne (Superhet) Sets
Sonora TSA-105 or 155 (1940)Sonora Radio, New York, NY. MIDGET Transformerless using 1st generation AA5 tubes (50L6GT, 35Z4GT, 12Q7GT, 12K7GT and 12A8GT).
Very Small (5" H X 8" W X 4.5" D)
Above: Tube glow and tight quarters.Below: Restoration complete
Emerson CL-246 (1941)Emerson Radio Corp, New York, NY. Midget Plaskon Radio. Transformerless using 1st generation AA5 tubes (35L6GT, 35Z4GT, 12Q7GT, 12K7GT and 12A8GT).
Knobs are not the original type, but the color is correct. Notice that the crack on the top of the plaskon cabinet is fairly common on midget radios, due to heat from tubes.
Inside the AA5 Emerson CL-246, not much room with prewar octal tubes. Cabinet gets hot so not surprising to find cabinet cracks.
Left:
Plaskon plastic cabinets tend to be translucent, allows scale light to glow through cabinet.
Plaskon plastic cabinets tend to be translucent, allows scale light to glow through cabinet.
RCA 5X5 "Little Nipper" (1938) RCA, New York. This is a very interesting superhet midget. It serves as a personal radio and has a built in AM broadcaster to allow other radios in the house to receive the same station it is tuned to. The transmitting frequency is around 540 to 800 KIHz and utilize the power line as an antenna. Can also make records with phono input line. An AA5 with a different tube complement. 12SA7, 12C8 IF AMP, 12SC7 Amp and Xmit OSC, 35L6GT and 35Z5GT
BELOW: Tightly packed top of chassis! The second IF is under the chassis at the front center. One can see the adjustment padding caps on top.
ABOVE: New capacitors were used. Noticed how much room was revealed. Did not stuff new PTFE capacitors into old paper capacitor housing as shown LEFT: in original as found wiring. The original caps took too much space and would be difficult to put back and potentially damage other parts.
The FADA 1000 "BULLET" : A CATALIN Plastic Radio
The FADA 1000 "BULLET" : A CATALIN Plastic Radio
FADA used this style from 1941-1942 and 1946
(Fada Radio & Electric Co, Long Island NY)
Bakelite was one of the first materials used for radio cabinets based on plastic or composite materials. They were heavy, brittle and came in dark brown or near black. The color had to be painted on. By beginning of the 1940's a type of plastic called Catalin could be molded with the color already in. This lower the production cost, made the radio lighter, and the choice of colors was big. Shown below is my restoration of the FADA 1000 (The Bullet) made in 1946 but it was a carryover from the prewar series started in 1941. good to excellent condition can fetch a high price. Catalins are highly collectible and in very Found this at a Goodwill Thrift Store for $4 back in the early 1990's. If you look at the picture above you can see the light from the dial panel showing through the plastic. This is an easy way you can identify the CATALIN plastic radio.
RESTORING THE ELECTRONICSAll paper capacitors were replaced with PTE Molded capacitorsThe Filter Capacitor was a sealed aluminum FP Twist Lock type. It was cut open, cleaned out in new reliable aluminum electrolytics were installedAll out of tolerance resistors and power handling resistors were replaced with more reliable metal oxide types.
RESTORING THE ELECTRONICSAll paper capacitors were replaced with PTE Molded capacitorsThe Filter Capacitor was a sealed aluminum FP Twist Lock type. It was cut open, cleaned out in new reliable aluminum electrolytics were installedAll out of tolerance resistors and power handling resistors were replaced with more reliable metal oxide types.
FADA probably felt that they could use this radio during the postwar because the style was popular so no new engineering was needed.
Original Paper Capacitors
New PTFE Caps installed
<<<<<<<<Remove old electrolytic assembly out of can and rewire base with new elecytrolytics
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Install new caps and glued on can cover.
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Install new caps and glued on can cover.
TOP VIEW OF CHASSIS (Pre War Octal Tubes and IF Transformers)
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