Zenith Model 5-R-317 (5R317) "Glass Rod" Radio (1939)
I found this magnificent Art Deco Zenith 5-R-317 radio early one morning at the Brimfield
show a few years back. It is often referred to as the "World's Fair" model after it, and its
sisters, appeared at the 1939 New York World's Fair, where Art Deco design was center
stage. Little was it known at the time but that fair would portend the Grand Finale of the
Art Deco period. World War 2, which soon followed, ushered in an era of austerity. Once
it was over the particular exuberance of the Art Deco period was forever gone.
Zenith 5R317... World's Fair Crystal Grille Automatic Special.
|"Beautiful walnut finish with sparkling
crystal grille - Expensive Transcontinental
Automatic Tuning -- scintillating tone"
"the most perfect tuning since Zenith first
put Automatic Tuning on a radio in 1928"
The original purchase price of this radio was $29.95, though in good condition, some have sold for upwards of $700 today. The
model was introduced in June of 1938 as part of Zenith's line-up for the 1939 season. As a point of reference, the New York
World's Fair itself did not officially open until April 30th of 1939.
The chassis is an ac-powered 5-tube superheterodyne having tube line-up 6A8G (LO/mixer), 6K7G (IF amp), 6Q7G (2nd
detector/AVC/1st AF), 6K6G (power amp) and 6X5G (rectifier). It tunes the standard broadcast band.
When I found the radio, it had one broken glass rod, one missing push-button and had been brushed with Shellac. I got a
replacement rod and button from www.gn4radios.com. One of these days I'll attend to the finish, but it looks so good I'm in no hurry.
The 5R317 was described by Zenith as featuring their "Transcontinental Automatic Tip Touch Tuning" system, a new innovation for the
1939 season offered on sets costing $19.95 or more. With this technique, automatic tuning is accomplished electrically, by the
switching in-and-out of tuned circuits, rather than by rotating the tuning condenser to the desired spot. The 5R317 is tuned using
either the regular rotary tuning knob (lower right), active when the lowest push-button, labelled "dial", is pressed, or by pushing one
of the 5 "automatic tuning" buttons, preset to a favorite station. Only the lightest pressure is required for activation, hence the
description "Tip Touch".
In a newspaper article from June of 1938, the invention was described thus:
"According to Zenith officials, Transcontinental Tuning was so named because it works equally well on a combination of standard broadcasts,
distant and local stations as it does in a combination of all local stations. It is described as being just as selective and sensitive as tuning by hand,
a thing according to Zenith engineers never before accomplished in any radio set. A further claim made for this type of tuning is that it does not
drift due to changes in heat or humidity, stations do not wander and once the button is set for the station, it will always come back again at the
same spot. Frank Smolek, service manager for Zenith demonstrated how a customer can set up the Automatic Tuning for himself with the aid of
only a screw driver."
"No longer is an expert service man with an oscillograph needed, say the makers, because all one has to do is to slip off the snapplate cover that
carries the call-letters for each button and turn a small screw to the station wanted. Just as the notes of a slide are moved up or down, so the
desired stations will come in one by one as the listener moves the screw up or down."
This all reads like the specification for the ideal tuning system, one to which all automatic tuning radios of the day aspired, and
almost too good to be true for a set, such as this one, not having any means of Automatic-Frequency-Control (AFC). However,
Zenith did claim to have paid special attention to minimizing drift to acceptable levels in their circuits, through the application of
sound engineering, including the use of low-drift components and solid construction techniques. Moreover, much of the drift
associated with early tuning systems was attributable to their predominantly mechanical nature. The Zenith system was
fundamentally electrical and did not rely on the movement of relatively imprecise mechanisms, such as those still in use at the time
by many other manufacturers. These generally mandated AFC in order to work satisfactorily, free from tweaking by the listener.
Finally, Zenith claimed to have laboratory and field-tested their innovation extensively, so overall it probably worked very much as
they claimed it to.
One of the main drawbacks of using the early electrical tuning systems was that when automatic tuning was in effect, the dial
pointer was left pointing at the wrong spot on the dial, which could be very confusing to the listener! (though to be fair, most sets
turned off the dial illumination once automatic tuning was selected). Perhaps it was because of this that many manufacturers
seemed reluctant to abandon the mechanical approach. Of course it would be many years, pending the advent of synthesiser
tuning and numerical displays, before this problem would be finally put to bed for domestic radio.
...with Transcontinental Automatic Tip-Touch Tuning.
|Zenith's Tip-Touch Tuning Innovation