..extract from 1933 Zenith advertising.
Zenith Model 715 Tombstone Tube Radio (1934)

The very ornate Zenith model 715 "midget" style radio was
introduced in the summer of 1933 (based on an Aug 1933
announcement in Radio Retailing). It was one of the series
700 radios referred to by Zenith as their "new Challenger
line". In September of 1933 this radio could be purchased
for $49.95, complete with tubes, in the East.
The 715 features shadowgraph tuning, introduced by Zen-
ith the previous season and very similar to that used for
certain contemporaneous Philco sets, such as the 19B. In
promoting this tuning aid, Zenith used advertising copy
very much like Philco's, proclaiming it as a "device that
makes every child or grown-up an expert tuner".
Whereas Philco would continue to use their basic electro-
mechanical shadowgraph through 1938 (after which time
they abandoned visual tuning aids altogether), Zenith, for
1937 refined it to provide "target" or "bullseye" tuning. A
year later they adopted "all-electric" target tuning, based
upon "magic" eye tubes, which they would continue to use
through at least 1946. Tuning eyes can be counted as one
of the features that make the latter 1930s Zenith sets so
popular among collectors today.
The 715 is an 8-tube ac-powered super-het covering the
standard broadcast band. Tube line-up is 58 (RF amp), 58
(mixer), 56 (LO), 58 (IF amp), 55 (2nd det/ AVC/1st AF), 59
* 2 (AF push-pull power output) and 80 (rectifier). The
schematic can be found here, courtesy of NostalgiaAir.
New Challenger Model 715 ..a masterpiece in tone, design, reception.
"8-tube Superheterodyne, Shadowgraph tuning, advanced type automatic volume control. 8" dynamic speaker. The cabinet has matched butt-walnut front with pilasters inlaid with genuine marquetry and overlaid with maple burl. Reeded ends. Hand rubbed, hand polished finish. Size 191/2" high, 16" wide, 91/2" deep"
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Shadowgraph Tuning "Here's the device that makes every child or grown up an expert tuner. When a station is not tuned to exact resonance a wide black shadow appears on the screen [ed]. As the station comes closer to the peak, the shadow becomes smaller, until finally, when tuned "on the nose", only a narrow black vertical line shows. Result: full rich resonance, not a rasping sound."
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..extract from 1933 Zenith advertising.
Copyright TubeRadioLand.com
Oct 31st 1933, Ohio
Nov 5th, 1933, Tx
Dec 9th 1933, Pa
Apr 23rd 1934, Tx
Oct 1933, Radio Retailing,
pg 1
191/2" (H) * 16" (W) * 91/2" (D)