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Advertising Graphic Used for Zenith's 1938 Robot Dial
Zenith 12-S-267 (12S267) Shutter-Dial Console Radio (1938)
The magnificent 12-tube Zenith 12-S-267 (12S267) console
radio, introduced as part of Zenith's 1938 line in June 1937,
is a much coveted set that is an uncommon find today. It
had an original purchase price of $169.95 and boasts the
following list of features:-

  • Motorized tuning & foreign station re-locator
  • 12-inch electrodynamic speaker with "acoustic
  • adapter"
  • Push-pull 6V6 output stage producing a room-
  • filling 15W
  • Three waveband tuning range (BC/SW1/SW2)
  • Robot (shutter) dial with tear-drop shaped
  • escutcheon
  • Tell-Tale controls
  • Local/distant reception switch  
  • Tuned RF stage with triple filtering
  • 5-point tone control (voice/normal/Hi-Fi/Bass/
  • Foreign)
  • Deluxe cabinet in exotic veneers
  • Tuning eye

The tube line-up is:-

  • 6K7G (tuned RF stage)
  • 6L7G (1st detector or mixer)
  • 6K7G (IF)
  • 6J5G (oscillator)
  • 6H6G (2nd detector/AVC)
  • 6J5G (1st AF)
  • 6J5G (2nd AF)
  • 6J5G (phase inverter)
  • 6V6G - 6V6G (push-pull output)
  • 6T5 (originally), now 6U5 (eye tube)
  • 5Y4G (rectifier)

Frequency coverage is 540 to 1752, 1740 to 5930 & 5490
to18400 kcs.

Although the tone control offers a Hi-Fi setting, this is not
achieved through widening of the IF bandwidth - contrary to
the approach taken by Zenith's top-of-the-line Stratosphere
models and also by a number of Philco, RCA, Stromberg
Carlson and other consoles of the era. In fact, the RF/IF
section of the 12S267, although adequate, is rather con-
ventional. Zenith instead focused on producing a radio
having great audio, outstanding cabinetry and unrivalled

The loudspeaker is fitted with an
acoustic adapter, seen in
the photo below right. This is basically a conical form that
can be slid away from the loudspeaker to increase bass
response or pushed closer in to dampen it. The claim was
that it could compensate the acoustical characteristics of
any room. I must say that unlike the gimmicky acoustic con-
trivances offered by many radios of the era, this one turns
out to be quite effective, as even a modest repositioning of
the adaptor produces a noticeable change in bass repro-
duction. The 12S267 in fact produces the room-filling "big
sound" that Zenith is famous for and is certainly amongst
the best sounding Zeniths that I have encountered!

To the right are some original ads featuring the 12-S-267.
Note the 1937 Robot alongside the caption "Does your tun-
ing work for you" in one of the ads! The advertised price for
the 267 of $149.9 in one of the ads appears to be an error.

Restoration Notes

When I purchased this radio in early spring of 2006 it had
been partially re-capped. However, upon getting it home I
found the performance somewhat disappointing. A cursory
investigation revealed that one of the 6V6G output tubes
was running cool and  I soon found this to be the result of
an open output transformer primary winding. I ordered a
compatible replacement from
radiodaze and installed it on
the rear of the loudspeaker in place of the original. The
radio sounded much better but I still felt that something was
missing, after all, I've heard so much praise heaped upon
these big Zeniths for their sound quality.

So next I turned my attention to completing the re-capping
that a previous owner had begun. The first thing I noticed
was that several of the replacement components had just
been "tacked" into place using a small amount of solder and
it did not take much to pry them loose. I ended up replacing
or re-soldering most of these. Unfortunately, the originals
had been discarded and on high-end sets such as this I
generally like to re-stuff the carcasses with the new comp-
onents so as to preserve the original appearance. But so
be it. However, I did re-stuff all remaining caps as well as
replace a number of out of tolerance resistors.

A good 6E5 eye tube had been inserted by the seller but it
was not opening or closing, so I installed a new 1Meg res-
istor in the base of the tube's socket and that did the trick.
While the socket was dis-assembled, I replaced the crumb-
ing rubber-covered wiring between it and the chassis. The
6E5 now functioned but it had a tendency to produce an
overlapping pattern on strong signals, so I replaced it with a
new 6U5. The 6T5/6U5 tubes feature reduced sensitivity to
eliminate this problem. The
schematic calls out a 6T5 type,
but these are now extremely rare. The 6T5 and 6U5 are
electrically equivalent, though the 6T5 produces an
pattern compared with the 6U5 and 6E5
fan-shaped patt-
erns. If I ever come across a good 6T5, perhaps I'll install it
in this radio!

When I first operated the set  following completion of recap,
it would burst into a very loud, house rocking, low-frequency
oscillation when playing program material with any sort of
low-frequency content at anything but the softest volume. At
first I thought it was acoustic feedback and indeed some of
the audio tubes turned out to be overly micro-phonic. How-
ever, the problem persisted when these were replaced.
After checking my component replacements and finding all
to be fine, I compared the wiring
layout (dress) against
photos of an untouched original 1204 chassis that I saw on
Ebay. I had taken chassis photos prior to commencing my
work but I wasn't sure to what extent the layout had been
disturbed by previous owners. Upon re-dressing the wiring
and components in the audio stages to match the original,
the problem went away.  Just goes to show the importance
of preserving the original layout when replacing compon-
ents in these radios with high-gain audio stages! The radio
is now a great player and every bit lives up to my expectat-
ions for a big Zenith.
Zenith...America's most copied radio ...again a year ahead.
Zenith 12-S-267 Console Radio Dial Close-Up
Zenith 12-S-267 Chassis #1204 View
Acoustic Adapter as used for Zenith's 12-S-267 Console Radio
Zenith 12-S-267 Console Radio (1938)
Sept 30th 1937 Va
Oct 1st 1937 Tx.
Sept  1937
Dec 1937, Illinois
Click any thumnail to enlarge