1930-1937 The Depression and the Rise of the Golden Age of Radio
Page 2
Page 2
Compact or Midget Radios
Compact or Midget Radios
In order to cut costs, radio manufacturers tried to do parts cut, shrink cabinets and simplify circuits. Often with current technology the result was pretty significant. The phrase "you get what you pay for" really holds true. However as technical advances continued the compact radio became a mainstay in the late 1930's and thereafter.
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Philco 57C (1933) Philco Radio, Philadelphia PA 4 Tube Superheterodyne receiver using 2-77s, 42 and 80 vacuum tubes. Philco employed a power transformer as well. Philco always made quality sets, even at the lower end of the price scale. 1933 suggested price $15.
Inside the Philco 57C to show what is compact with 1930 technology
Crammed with parts underneath and on top.
ABOVE: Notice on the top side of chassis the FOUR holes coming out from the side. These are the IF transformer peaking trimmer capacitor. The IF frequency is 460 KHz.
BELOW: The two large cans on the left are the IF transformers and the 4 IF peaking capacitors on the top. This left little room for the rest of the components. The black boxes on the lower right are capacitor assemblies, where one or two paper capacitors are wired inside and then sealed in tar. The top of these boxes have terminals where other parts are mounted. Problem with these assemblies is that the entire assembly had to be replaced if defective OR pull out the old parts and stuff a new one in.
BELOW: The two large cans on the left are the IF transformers and the 4 IF peaking capacitors on the top. This left little room for the rest of the components. The black boxes on the lower right are capacitor assemblies, where one or two paper capacitors are wired inside and then sealed in tar. The top of these boxes have terminals where other parts are mounted. Problem with these assemblies is that the entire assembly had to be replaced if defective OR pull out the old parts and stuff a new one in.
Trav-ler 50A Karenola (1935) Travler Radio Corp. Chicago4 Tube TRF , using 25Z5, 43, 6C6 and 6D6 tubes. Uses line cord resistor to makeup balance of voltage not used for tube heaters, common in early transformerless radios of that time period. These line cord resistors would make the AC cord get warm. If it goes bad you had to get the exact replacement.
Chassis cleaned and polished!
Under chassis completely restored. New capacitors inside the original Ariston Lab paper and electrolytic capacitors. All dogbone resistors were in tolerance. The only modification was the addition of a 180 ohm 10 watt resistor (lower left) to replace the open line cord resistor. I added a polarized plug with the correct connections to minimize shock hazard.
Echophone 110 and 111 (1934). Echophone Radio Corp, Waukegan IL.. 4 Tube AC/DC TRF radio. Uses 77, 78, 38 and 12Z3 tubes. Uses a line cord resistor that drops the voltage from 115 to 40 volts, so it gets pretty warm.
ABOVE, other than the electrolytic capacitors only one paper capacitor was bad. The others were very good.. Capacitors were made by Ariston Labs.
After unbolting the assembly. The assembly case is bakelite on top with the bottom side sealed in a tar like material. In time the tar hardens and will crack or deform allowing moisture in.
Heat the tar and then scoop it out exposing the paper capacitors.
Clean the housing and install new parts into the correct eyelet feed thru. Reassemble into chassis.
ABOVE- With original back cover. BELOW- Glowing tubes.
Solution- Just bend the area where the IF transformer shield can touch the 78 tube pin inward to provide enough clearance.
BELOW: Band select switch in on the rear of the Sparton 594 radio. Pull tab out for SW and push in for std broadcast.
The power transformer for the Gilfillan was made by INCA of Los Angeles. I've seen this brand on several LA made radios. They always have the shiny silver enclosures.
CABINET before and after restoration.Radio was painted wrinkled white paint on the entire cabinet. Discovered that the set once had a handle on top and other versions had a handle so I manage to get a very similar brass handle. Gilfillan 4 and 4T had several different cabinet styles. This one has a burl walnut panel a boxy shap
Dial Light
Westone 20 (1934) : Los Angeles Radio Co, 4 Tube TRF radio using 56, 58, 2A5 and 80 vacuum tubes. Uses a power transformer. Westone made very low priced radios, most were bare bones radios, good enough for local stations. Garage type operation.
Inside the Westone 20.
When I restore this set, I did not save the original paper capacitor tubes and stuff new ones in. Only the box electrolytic was done. All the dog bone and wire resistors were good. This set AC line was rewired to use a polarize plug for safety.
The back side of the Westone 20, showing the tubes glowing.
Sparton 594 (1934) Sparks Worthington CoA 5 Tube Superheterodyne using 2-78s, 75, 43 and 25Z5. There is a Sparton 506 that shares the same chassis but with a different cabinet. Transformerless radio, using a line cord resistor to make up balance of voltage not used for tube heaters. It was common for the line cord resistor to open up and one would have to get the exact replacement.
A Lot more crammed before. When I originally restored the set, I couldn't see any reason to restuff paper caps and keep the original look, except frustration. Now I might have tried it, but as one can see it would be so tight. On the upper left I recently installed a voltage dropping resistor because the line cord resistor finally opened up. One can see how little room there is to it in.
TIGHT ON TOP TOO! The Sparton chassis is about an inch wider than the other set shown on this page. This has 5 tubes to the 4 tubes on the other sets. Not much room to work with.
Gilfillan 4/4T (1934-35), Gilfillan Brothers, Los Angeles.4 Tube TRF radio. Uses 57, 58, 2A5 and 80 tubes. Gilfillan had the distinction of being one of the few west coast radio manufacturers to be licensed by RCA. Many Los Angeles manufacturers, contracted with Gilfillan to design radios (cabinet not included) for them. Gifillan after WW2 would become a strictly defense contractor.
Chassis all cleaned up. The knob at the lower left is the band selector. The metal box on the upper right is the electrolytic capacitor assembly.
SHOWCASE
Radio Restoration Challenges- Frustrating or Rewarding?
Westinghouse WR-21 (1935): A Personal Experience
Inside the set. Notice in the small button batterynext to the tube shield, that's a bias battery.
Many years ago, I picked up an interesting midget radio from the depression era. It had the nameplate Westinghouse, but I couldn't find the model number. When I took out the chassis, the radio had been worked on with many modifications/repairs. Since I couldn't find the model number I took a chance, looked at radio schematics of the 1930's that used the same tubes and worked from there. Got the radio to work but what model was it? After a lot of detective work, I came up with nothing and put the radio aside in hopes that someday I will locate the model. Some 10+ years later, I was selling off radios that I felt weren't worth keeping and this was one of them. I took one more careful look at the cabinet and with the light in the right direction I could barely see a model number punch stamped into the wood on the bottom of the cabinet. I could barely make out WR-21 with the "W" really faint. This confirmed it is a Westinghouse model made in 1935 according the Rider's Perpetual Servicing Notes.This is an early example of AC Transformerless Radio using 5 tubes, a design philosophy that would continue to the end of vacuum tubes as the "All American Five" (AA5) Tube Radio. Problem was that the layout of the radio is the same but tubes did not match the WR-21. It is a 5 Tube Superheterodyne radio using 6A7, 6D6, 75, 42 and 25Z5 vacuum tubes.There was no service notes on any changes like this. The mystery continues. I did more research into the 1936 model year and Westinghouse came out with the WR-100. The WR-100 is a small tombstone style rather than the midget and has a chassis layout a lot different than mine. However it used the same tubes as my radio. After pondering this I took a guess that my WR-21 was a mid year upgrade since tube technology and standardization was rapidly moving. Westinghouse made a design change using the newer tubes and put them in the WR-21 and did not update the service notes. I rewired most of the radio to the WR-100 design. It was difficult and frustrating at times because midget radios have very little room to work with so it was difficult to see if one was making the right connection. After about a week of rewiring and checking over I was done. Then I noticed in the schematic a small button battery was used to bias the grid of the First Amplifier Tube (type 75), which was not on the WR-21 schematic. After some research I found that a battery was sometimes use to bias a tube because it was cheaper to use a battery than a resistor in those days. Since in this application the battery would last for the life of the set which usually wasn't too long since midget radios were generally throwaways. It was a cost effective approach which is the reverse today. Made a 1935 equivalent battery circuit with 2012 parts and positioned it as it might have been in 1935. Turned on the radio and it works! I'm keeping this radio it was worth the wait!
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