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The Kadette Jewel Model 40 Chassis 3-Tube
Ultra-Midget Receivers Models 41, 43, 44 and 48
Radio Service Data Sheet
July 1936 Radio-Craft

July 1936 Radio-Craft

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

For many years I have been scanning and posting schematics & parts lists like this one from a 1936 issue of Radio-Craft magazine. It features the Kadette Jewel Model 40 Chassis 3-Tube Ultra-Midget Receivers Model 41, 43, 44 and 48 radios in graphical format. It is able to be "miniature" because only three vacuum tubes are used - although a 12A7 diode / tetrode effectively makes it a 4-tube radio. I'm guessing the Kadette Midget might have only worked well in strong signal areas. Often times I run OCR on them to separate the textual content. The radio shown in the thumbnail is currently being offered for sale on eBay†; the price seems a bit steep. The case appears to be in fine physical condition, but the electronics could stand some rework. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. I will keep a running list of all data sheets to facilitate a search.

† Usually when I find an item like this on eBay, I have Archive.org's Wayback Machine grab a page snapshot of it and link to it rather than the original eBay page because it will soon disappear. Here is the RadioMuseum.org webpage for the Kadette Jewel Model 40.

The Kadette Jewel Model 40 Chassis 3-Tube Ultra-Midget Receivers Models 41, 43, 44 and 48
Radio Service Data Sheet

A.C.-D.C. operation; new type balanced-armature speaker; range, (Size, 5 1/2 x 7 1/2 x 3 3/4 ins.; molded bakelite cases in many colors; 550 to L600 kc.)

The circuit of this receiver is of the A.C.-D.C. type, the 12A7 tube, V3, acting as both rectifier and power tube. Voltages are as follows:

These readings are taken with the volume control on full and no-signal input. All voltage readings except the heater taken with a 1,000 ohms-per-volt meter, to chassis. The circuit is one of extreme simplicity (which accounts for the long trouble-free performance to be had). The set runs quite cool due to the fact that the dropping resistor is in the line cord. A magnetic speaker of new construction is employed and will give good service without the need of any adjustments. The case is of solid molded bakelite and may be had in several different colors. The speaker grilles are detachable and are also supplied in several finishes. The set is ideal for the traveler, since it is so small, and a suede carrying case may be obtained for carrying and protection. Since V3 is a dual tube, the set gives a performance equal to those using 4 tubes, resulting in very high sensitivity for a set of this type. To test for alignment, insert a thin strip of mica, bakelite, or celluloid between the plates of the tuning condenser sections. Tune in a signal then open the condenser slightly below the point of resonance. Insertion of the feeler should now increase the signal, and as the feeler is pushed still farther between the plates, the signal should drop off. Correction for incorrect adjustment is made by bending the plate sections at the point of mesh, checking at 1,000 and 550 kc. The trimmer condensers should be set for best gain at 1,500 kc.

Posted July 13, 2022
(updated from original post on 8/27/2015)

Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 227 Radio Service Data Sheets as of December 28, 2020.

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The Kadette Jewel Model 40 Chassis 3-TubeUltra-Midget Receivers Models 41, 43, 44 and 48Radio Service Data SheetJuly 1936 Radio-Craft

The Kadette Jewel Model 40 Chassis 3-Tube
Ultra-Midget Receivers Models 41, 43, 44 and 48
Radio Service Data Sheet
July 1936 Radio-Craft