Even in the economic climate of 1930s America, there was still a market, however slight, for luxury radio receivers. The Scott Radio Laboratories had their Philharmonic; Philco had its 38-116 and massive 38-690; and there was the mysterious Crosley WLW receiver, about which little is known today. The Zenith Radio Corporation, headed at the time by the flamboyant Commander MacDonald, was not to be outdone. They entered the market with their Stratosphere – for its time, a marvelous piece of technology with cabinetry to match.
Zenith's first Stratosphere model was introduced in late 1935, to take advantage of the 1936 radio season. Two versions were made available, the 16-A-61 and the 16-A-63. They were electrically identical; the difference being in a more ornate cabinet for the 16-A-63. These receivers featured a 16-tube chassis, at a time when five to seven tubes was the most to be found in the average home radio. This first version of the Stratosphere featured a powerful audio amplifier consisting of four 6F6G tubes in a push-pull parallel configuration, driven by a single 6F6G. Feeding this amplifier was a fairly standard superheterodyne circuit, one that might've been typical in better Zenith radios of the era, though with better design and parts.
The front of the radio featured the famous Zenith “black dial”, a large circular dial with each tuning band lit up separately in its own color. It resembled something out of an airplane and was complimented by two pointers, one to indicate received frequency, and one for handy logging of received stations. The dial was framed by an intricate metal escutcheon, and above the dial was a small window for the Shadowgraph – a tuning indicator device intended to aid the listener in accurate tuning.
All this was housed in beautiful cabinetry. The 61 was available in the usual type of “living room” style of radio cabinet, such as might be seen on Zenith's console radios, but made of better woods and veneers. The 63, however, came in a more elaborate cabinet with sliding doors, inlaid marquetry, and solid walnut pilasters.
Late in 1936, Zenith pulled out all the proverbial stops and introduced the model that most think of when they hear “Stratosphere” - the Model 1000Z. This was a radio designed for those to whom price wasn't much of a consideration; the 1000Z featured 25 tubes, including eight type 45 triode tubes, again in a push-pull parallel configuration, driven by two type 42 tubes (the older version of the 6F6G) and a type 76 tube. Audio bandwidth could be controlled from the front panel, courtesy of a variable-bandwidth intermediate frequency circuit that determined the selectivity of the radio and thus, along with the tone controls, the audio response of the receiver. All this was directed to a bank of three high-quality “Concert Dynamic” speakers: a large woofer for the bass frequencies, and two tweeters for the treble.
To match the power in the audio circuits, the 1000Z made use of two radio-frequency stages (none was the norm in most radio receivers of the day) and two intermediate-frequency stages to provide plenty of front-end amplification and sensitivity in the superheterodyne circuit. Tuning was again simplified for the user with the Shadowgraph prominently placed below the large, circular dial. Zenith was known for using the best components available; in the 1000Z, they used the best of the best – this receiver was intended to rarely see the inside of a repair shop.
As for the cabinet in which the 1000Z was housed ... the description from Zenith's 1937 dealer catalog says it best:
A symphony in rare wood. Rare woods blended into a symphonic harmony of exquisite color emphasize the true character of the Zenith STRATOSPHERE as a genuine musical instrument. Design has been dictated by the basic principles of acoustics, just as is that of the violin. Outstanding charm is the result. Solid walnut pilasters are combined with Australian laurelwood. The superstructure is Carpathian elm burl, inlaid with imported marquetry; a note repeated in the center of the grille. Doors are of matched American butt walnut, overlaid with marquetry. The entire ensemble is enhanced by a natural piano finish of satin sheen. Nothing finer has ever been produced by craftsmen in wood.
Flowery language, indeed, but not far off the mark for this receiver. Few of these elaborate receivers have survived to the present day; of those that have, most collectors understand they're dealing with a part of radio history, and take appropriate measures in restoring the receivers. A registry exists to track the remaining receivers and for many, the Zenith Stratosphere is the jewel in their collection.
Radiomuseum, 16A61 Stratosphere (16-A-61 Ch=1601)
. <http://www.radiomuseum.org/r/zenith_16a61_stratosphere_16_a_6.html> (October 2006)
Old Radio Zone, Zenith Stratosphere
. <http://www.oldradiozone.com/strat.html> (October 2006) (source for the Zenith Dealer Catalog passage