High-Fidelity Speaker System: - the 14" electrodynamic loudspeaker used in the 116XX is constructed in two
sections made out of different grades of paper. The inner section is made stiffer and more amenable to
reproducing high frequencies, whereas the whole works well for the lower frequencies. Additionally, it's likely that
the voice coil was constructed using aluminum wire for lightness, again out of consideration for high frequency
capability. This was certainly the case on loudspeakers used by some of Philco's earlier Hi-Fi sets (e.g. the
201X) and was likely the case on this model too.
A sound diffuser is embodied into the loudspeaker opening behind the grille cloth for the purpose of diffusing
high frequency energy and lessening beaming. The diffuser (photo mid-right) comprises a small conical element
inserted into the loudspeaker opening directly in front of the center of the loudspeaker cone - a hidden feature
of the set that most listeners probably never even realize is there! In all likelihood, the five vertical wooden fins in
front of the loudspeaker grille were conceived of as part of the sound diffuser also*, serving more than just a
mere cosmetic function and acting much like the concealed metallic fins in the model 201X. Other's such as
Emerson, with their "miracle tone chamber" had done the same thing. In addition to the diffuser, the set utilizes
Philco's famed "inclined sounding board", which directs the entire sound field slightly up and away from the floor.
The 38-116X includes three small diameter acoustic clarifiers (right), designed to absorb energy at the cabinet's
resonant frequency and thereby lessen boom, which if unchecked is particularly detrimental to the reproduction
of voices. It is interesting to note that in the first year of their appearance (1936 season), two different sizes of
clarifier were used. The 1936 model 116X used three clarifiers, one with an 8.75" cone and two with 6.25" cones.
US patent #2059929 (granted 11/03/36; inventor Bobb, L.J.; Assignee Philco Radio and Television Corp) explains how these
three units act in concert to reduce the primary cabinet resonances occurring between 70 and 150Hz, the
maximum reduction being around 10dB at 95Hz. Later sets, including the 38-116XX, discarded the larger
diameter clarifier and used three 6.25" units. Apparently, Philco was able to realize the requisite degree of
resonance flattening using just the smaller 6.25" clarifiers.
Note that in none of the sets using acoustic clarifiers is a cabinet back necessary for correct operation - it is a
common misconception that these devices will work only if a back is affixed to the radio. Cabinet resonance is
however noted to be greater when the receiver is placed near to a wall, so the influence of the clarifiers in
reducing boom is then the most pronounced. The 38-116XX was sold with a protective rear cover in place (right),
but this served a protective rather than acoustical function.
As well as donating a number of "exact" replicas of the ten-millionth Philco to veteran's
hospitals throughout the USA, Philco offered a limited number for sale. They were
sold with a plaque affixed to the base of the inclined control panel, bearing an engrav-
ing of the purchaser's name preceded by the words:- "Exact Replica of the Ten Mill-
ionth Philco. Built for" (click thumbnail, near right).
To promote sales of the 38-116XX at this time, Philco ran a national advertising
campaign based around their "crowning achievement in radio", the ten-millionth set.
Interested parties were invited to visit their local dealership to see and hear an exact
replica of the radio. Once there, they could submit a coupon for a free copy of a
Souvenir Brochure entitled "The Story Behind The Ten Millionth Philco" and a copy of
"The Philco Mystery Book", containing an entry blank for "Philco's Radio Mystery
Contest" offering $50,000 in cash prizes. In the store, of course, they would learn how
easy it was to own a 38-116XX radio by taking advantage of Philco's "only a few
dollars down" financing offer, combined with generous trade-in allowances against
Overview: The 38-116XX is a 15-tube all-wave AC superheterodyne having five frequency bands with automatic tuning, an RF amplifier, a
mixer and LO stage with Automatic-Frequency-Control (AFC), two stages of IF with variable selectivity control and a 15W High Fidelity audio
system with push-pull beam output stage, cathedral speaker and acoustic clarifiers. It came with either a code 121 or 125 chassis type, with
all but early production using the code 125 version. The 125 chassis simplified the number of adjustments required in the front-end and
modified the tube line-up. A rear view of my restored 38-116XX (with its protective back removed) may be viewed here.
My set uses the 125 chassis with tube line-up:- 6U7G (RF amp), 6A8G (mixer), 6A8G (LO), 6N7G (reactance tube), 6K7G (1st IF), 6K7G
(2nd IF), 6K7G (2nd detector/magnetic tuning amp), 6J5G (AVC diode), 6J5G * 2 (AFC discriminator), 6R7G (1st audio), 6J5G (single ended
driver), 6L6G * 2 (beam outputs) and 5X4G (rectifier). The 6J5 driver stage is transformer coupled to the push-pull outputs. The tuning range
is- 530-1600kc (band 1), 1580-4750 (2), 4700-7400 (3), 7350-11600 (4) and 11500-18200 (5). The schematic may be found here.
Automatic Tuning: The receiver incorporates Philco's Automatic Tuning dial, first introduced for the 1937 model season. You are referred
to PhilcoRepairBench for details on this dial's usage, setting up and service. The US patent for this tuning device, #2248678, was filed on
behalf of Philco on Aug 6th 1936 and was granted on July 8th 1941. It names the inventors as Glaser, Bowman and Briggs and makes very
interesting, if not somewhat challenging reading!
Magnetic Tuning: The receiver features an Automatic Frequency Control (AFC) circuit, referred to by Philco as magnetic tuning. This was
primarily added to work in conjunction with the Automatic Tuning dial mechanism for the purpose of correcting residual tuning errors. AFC
operates by sensing frequency detuning relative to the IF center frequency (470kHz for the 38-116XX), automatically adjusting the frequency
of the LO so as to drive any tuning errors towards zero. Three of the receiver's tube complement is devoted to this purpose.
Variable IF Selectivity: The receiver's selectivity is varied at the listener's discretion using a front-panel control that mechanically adjusts
the coupling between windings in each of the set's first two IF transformers. This control also links to a potentiometer used to apply additional
high-frequency cut to the output of the first AF stage as the IF bandwidth is narrowed. At it's widest setting, the IF bandwidth is such as to
permit reproduction of frequencies up to around 7.5kcs. This is around twice the bandwidth of standard IF filters of the day and in 1938 was
considered adequate for high-fidelity reproduction.
Bass Compensation: A three point bass control switch is provided that is ganged with the on/off switch. A tapped volume control
potentiometer automatically results in an increased bass response at low volumes to compensate for audiometric effects.
Automatic Volume Control: The AVC bus on the 116XX is connected only to the RF and 1st IF stages. The 2nd IF runs with fixed bias; to
have applied AVC to this stage would have increased audio distortion, especially in the presence of strong signals. Another aspect of the
AVC is that the carrier is sensed from the primary winding of the final IF transformer, rather than from its secondary (from whence is obtained
the 2nd detector input), as is more traditional. This necessitated the use of a dedicated AVC diode but has the advantage of minimizing
resistive loading on the IF transformer's secondary - an expedient found to minimize audio distortion. I have to confess that the AF from the
2nd detector on this set looks extremely clean when viewed on an oscilloscope with a CW modulated waveform applied to the antenna input
- far more so than on most AM radios that I've had the pleasure (or otherwise) of servicing.
Philco Foreign Tuning System: This actually covers a number of aspects concerning the front-end, primarily concerned with optimizing
sensitivity of the set and its ability to tune and separate stations (foreign or American).
Firstly, the set was designed to accept a balanced antenna input from a device such as the Philco High-Efficiency-Aerial-System. Each band
has its own tuned antenna input circuit, switched in and out by the waveband selector switch for the purposes of matching receiver to
antenna and thereby maximizing the transfer of signal energy to the receiver. Pick-up of noise from household wiring is also lessened
through the use of this arrangement (because of the balanced feed between outside antenna and receiver). A less efficient conventional
antenna input is also provided for temporary use during test, or for use by those not in possession of a High-Efficiency-Aerial.
A second aspect of the foreign tuning system is the use of split stators on the tuning condensors. Each of the three gangs on the condensor
is formed in two sections, comprising a larger and a smaller capacitance element. On the lowest frequency bands the two sections of each
gang are connected in parallel through the waveband switch, providing a large capacitance for effective tuning at the lower frequencies. On
the intermediate bands only the larger section is used, while on the highest frequency bands only the smaller section is switched in. This
expedient has the highly beneficial effect of providing a bandspread capability, i.e. of spreading stations further apart on the dial.
A third aspect is the use of a dial for which almost the entire 360 degrees is marked, in color, with frequencies and the names of stations. On
many other earlier or contemporaneous so-called All-Wave sets only 180 degrees was used for frequency markings and usually there were
fewer bands to boot with the result that stations were far more crowded together. No wonder Philco claimed "stations spread six times further
apart" in many of their ads for sets featuring their foreign tuning system.
The above features are further augmented through the use of a dual speed vernier tuning mechanism. Overall, these Philcos provide a
great feeling of "space" between stations that makes them a pleasure to use.
Philco Model 38-116XX (38-116) High-Fidelity Console Radio (1938)
Philco presents the radio of tomorrow today!
The Philco model 38-116XX console radio was one of eight "No Squat, No
Stoop, No Squint" sets introduced by Philco in June of 1937 for the 1938
model year. With an initial list price of $200 for what was truly a feature-
packed set, this radio provided great performance and extremely good
value to those who could afford to buy it. The 38-116XX was upstaged for
the 1938 model year only by Philco's showpiece 38-690XX set.
I initially purchased this set not for its looks but more for its technological
excellence and because it filled a void in my line-up of high-end Philcos.
However in short order I've come to appreciate its decidedly machine age
styling. It readily evokes fanciful impressions of a majestic streamliner,
forever speeding forth on a one way journey away from a long lost era. A
befitting image for this set, from the crowning year of radio's "golden age".
There can be no doubt that 1938 was technologically a banner year for
Philco, with their top models representing a pinnacle of achievement, the
culmination of many years of rapid advancement in the state of the radio
art. It's no wonder that the 38-116XX was referred to in many Philco
advertisements as "the radio of tomorrow today".
|"For 1938....Philco presents the radio of tomorrow today!
No longer need you squat, stoop or squint to tune a radio!
The minute you see the new 1938 Philco Double-X models,
you'll realize that the Inclined Control Panel makes
stooping to tune in a station as out-of-date as stooping to
crank an automobile!"
Philco made much play on the No Squat, No Stoop, No Squint theme in its
advertising, but, as they were quick to point out, "there's far more than the
inclined control panel to the Philco story for 1938. In the 1938 Philco 116 Double-X
you'll find all the latest Philco developments, everything you could wish for or hope for
in a radio". Below is a collage of extracts from original Philco advertisements
describing the features of the 38-116XX radio.
- Inclined Control Panel - No Squat! No Stoop! No Squint!
enables you to tune with ease and grace
- Philco Automatic Tuning - a flick of your fingers and in comes your
favorite station, tuned with absolute accuracy... instantly... perfectly.
- Magnetic Tuning
- Philco High-Fidelity - twice the tonal range of ordinary radios.... for
- Acoustic Clarifiers - prevent "boom"
- Wide Angle Sound Diffusion
- Inclined Sounding Board - brings music up to ear level
- Cathedral Speaker - exclusive Philco two-in-one High Fidelity speaker
- The Philco Foreign Tuning System - with spread band dial.. which
doubles the number of foreign stations you can get and enjoy... assures
you mastery of overseas reception...
- Fifteen Philco Tubes and five tuning ranges covering everything that's
interesting on the air. Anti-distortion Beam-Output Tubes...
- Individual and Personal Control of both treble and bass
- Everything you could wish for - in a cabinet of thrilling beauty.. with
"Tune easily, gracefully, Automatically! ...sitting or standing...!"
"Performance that is a revelation! ..tone that is glorious in its realism..."
All you could ask in radio.
During the late fall of 1937, Philco announced the production of its ten millionth radio - a model 38-116XX. To commemorate the occasion,
Philco presented the set to the Walter Reed Hospital in Washington D.C. at a ceremony that was a feature of the 1937 Armistice Day
celebrations in the Nation's capital. The set was presented to the veterans in the hospital by Boake Carter, famous Philco Radio news
commentator, representing the Philco Radio and Television Corporation. Secretary of War, Harry H. Woodring accepted the radio on behalf
of the veterans and servicemen. Every seat in the auditorium in the Red Cross House at the Great Army Medical Center was occupied by
soldiers and patients.
On a silver plate attached to the base of the inclined control panel of the radio, was the following inscription:-
Replicas of the ten millionth Philco were presented simultaneously with the Armistice day ceremony at the Walter Reed Hospital to the
various veterans' hospitals throughout the country.
Secretary Woodring, responding to the theme of the ceremony, said:-
"I know of no greater pleasure than to come here and accept this generous gift on behalf of the Walter Reed hospital. To my mind there is
no greater invention than the radio, especially for those who are hospitalized. Philco has given its 10,000,000th radio to the Walter Reed
hospital. I recall that when Philco produced its 7,000,000th radio, it gave that instrument to the Warm Springs Foundation, in which our
president is so interested. I say now that we express our admiration to Philco for this gift".
Summary and extracts from a report in: The Charleston Daily Mail, Nov 21 1937, p 10.
Philco's Ten Millionth Radio - a 38-116XX
|"This, the ten millionth Philco, is presented to the World War veterans in the Walter Reed Hospital in the hope that it
will bring them in closer contact with 'the good things on the air'. November Eleventh, 1937".
Back in early 1932 Philco introduced the inclined sounding board and heralded it as a revolution in radio. Models incorporating this feature
had an 'X' appended to the model number (e.g. 112X). When Philco introduced the inclined control panel in 1937, it was only natural for them
to add a second 'X' to the model number of sets incorporating both features. These became known simply as the Philco Double-X models.
The meaning of the 'XX' in the Philco 38-116XX
I recently completed what turned out to be a routine electrical restoration of this set and have since had the great pleasure of spending some
time listening to it. Although it does not use tweeters such as in the top-of the line 38-690XX, the sound quality from this receiver is superb!
There is little sense of boominess in the reproduction and mid-range timbre is close to that realizable from FM. Sensitivity across all bands is
first rate. Overall an impressive receiver that is a delight to use and listen to. One of Philco's best!
* I recently came across some Philco literature for the model 680X where it is stated that the three vertical fins visible in front of that set's loudspeaker compartment
were indeed scientifically designed to act as sound diffusers, in addition to fulfilling an aesthetic role.
|their old set. On a final note, the 38-116XX was originally listed at $200 in eastern regions of the USA, but at the time of the ten-millionth set
promotion in late fall, it was being advertised at around $230.
PHILCO MODEL 116 SERIES