Zenith Model 5-R-317 (5R317) "Glass Rod" Radio (1939)
I found this very Art Deco Zenith 5-R-317 radio
early one morning at the Brimfield Flea Market.
When introduced in June of 1938, it was called
the "World's Fair" model, perhaps in anticipation
of its appearance at the 1939 New York World's
Fair, which opened in April of 1939. Little was it
known at the time but that fair would portend the
end of an era. World War 2, which soon followed,
ushered in an era of austerity, and once it was
over the exuberance of Art Deco, the machine
age and streamlined everything, was gone.

The introductory purchase price of the 317 was
$29.95 in the East.

The chassis is an ac-powered 5-tube superhet
with tube line-up 6A8G (LO/mixer), 6K7G (IF),
6Q7G (2nd det/AVC/1st AF), 6K6G (power amp)
& 6X5G (rectifier). It tunes standard broadcast.
The schematic is
here, courtesy of NostalgiaAir.

When I found this radio, one of its glass rods
was broken, a push-button was missing and it
had been brushed with Shellac. I bought  a repl-
acement rod and button from

Zenith's Tip-Touch Tuning

The 5R317 features Zenith's "Transcontinental
Automatic Tip Touch Tuning",
an innovation new for
the 1939 model year that was offered on sets
costing $19.95 or more. The automatic tuning is
accomplished electrically by switching between
tuned circuits, rather than by mechanically
cranking the tuning condenser around to the
desired spot. The 5R317 is tuned using either
the regular rotary tuning knob (lower right), act-
ive when the lowest push-button, labelled "dial",
is pressed, or by pushing one of the 5 "automat-
ic tuning" buttons, preset to a favorite station.
Only the lightest pressure is claimed necessary
for activation, hence "
Tip Touch". A description
of the feature, clipped from a June 1938 news-
newspaper, is shown near right.

This promotional copy reads like the specificat-
ion for an 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-Freq-
uency-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 construct-
ion techniques. Moreover, much of the drift
associated with early tuning systems was attrib-
utable 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 satis-
factorily, free from tweaking by the listener. Fin-
ally, 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 autom-
attic 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 illumin-
ation once automatic tuning was selected). Per-
haps it was because of this that many manufact-
urers seemed reluctant to abandon the mechan-
ical approach. Of course, even though just about
all manufacturers did move over to push-button
electrical tuning within a short time period, it
would be many years, pending the advent of
synthesiser tuning and cost-effective numerical
displays, before this problem would be finally put
to bed for domestic radio receivers.
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"
...with Transcontinental Automatic Tip-Touch Tuning.
Tip-Touch Tuning Newspaper
Clip (June 1938)

"According to Zenith officials,
Transcontinental Tuning was so
named because it works equally
well on a combination of standard
broadcasts, distant and local stat-
ions 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 engin-
eers 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 Autom-
atic 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 snap-
plate 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."
Copyright TubeRadioLand.com
Dec 15th 1938, Oakland, CA
Aug 7th 1938, Va.
Zenith 5-R-317 Glass Rod Radio (1939)