Philco 111 Highboy Console Radio Main Page

Philco Model 111 Console Radio (1931)

The Philco 111 Highboy was introduced in January of 1931 and, as had become the norm, was heavily promoted by both the
company and its local dealers and retailers. It, and the model 111 lowboy, were Philco's first superhet radios, using their newly
developed 11-tube Superheterodyne-Plus chassis. "Never before such a radio as this", they announced, "Combining the exclusive
Philco balanced-unit screen-grid circuit with the superheterodyne, to do things no other receiver can do". As with their Neutrodyne-Plus
and Screen-Grid-Plus receivers before it, they used the word "Plus" in referring to the 111's circuitry. What is the meaning of
the "Plus" in Superheterodyne-Plus? I'll let them explain in their words, borrowed from an early advertisement:-

...never before such a radio as this.

Philco 111 - 11 tubes Superheterodyne-Plus.

Other features of the 111 include

Philco's station recording dial with glowing arrow indicator "for the surest and most accurate tuning radio in the world". This
dial allowed the listener to use a pencil to mark the precise location of favorite stations on the dial, thereby allowing
stations to be rapidly relocated following changes to the tuning.
Tuned RF stage, with dual input tuning and four gang tuning condenser
Dual IF stages
push-pull 245 output stage
built-in electrodynamic speaker
a local/distant ("range") switch, located on the chassis and accessible from the rear.
Frequency coverage from 550kc to 1500kc on the standard broadcast band

The tube line-up is 24 (RF), 27 (LO), 24 (mixer/1st detector), 24(1st IF), 24(2nd IF), 27 (detector), 27 (detector amp), 27 (af
amp), 45*2 (push-pull power amp), 80 (rectifier). The schematic is available here, courtesy of NostalgiaAir.org. For an
explanation of the model 111's detector and detector amp stages, see the description at the bottom of this page.

The 111 High Boy cabinet is made of figured walnut and the radio had an original sales price of $155, less tubes. You could
buy the set "complete to your aerial" with "Philco balanced unit tubes" for the princely sum of $173.

I found this at an outdoor flea market during the summer of 2004 - the seller had it standing out in the early morning mists at
6am. Finding it there quite made my day!

The Plus in Philco's New Superheterodyne-Plus

11-tube Power - More than the average owner needs, but wonderful to reach out and bring in the program you want.
Automatic Volume Control - Making this great power Useful by holding the reception at constant level without fading.
Tone Control - Four qualities of tone, "Brilliant", "Bright", "Mellow", "Deep" - Whichever you like, at the touch of a finger
Superheterodyne Selectivity - Combined with the sensitivity of screen-grid tubes, recognized as the most perfect circuit known.

Lucky 11: For 11 days we will sell the new 11-tube 111 superheterodyne at $11 down and give you 11 months to pay!

Below is the transcript of a discussion by Walter E. Holland, Chief Engineer of the Philadelphia Storage Battery Co., describing the meaning of Philco's 'detector' and 'detector amp' radio stages. He basically overviews the circuit developed by H. Wheeler of the Hazeltine Corporation that would eventually be used by most receivers, through the end of the tube era (though the two stages would eventually be combined into one combination tube, such as the 12SQ7). The Philco "Multiplex Detector"
"The two type 227 tubes which are used in our "multiplex detector" circuit separate the rectifying and amplifying functions of the usual single detection tube, and provide the means for automatically changing the bias of the control-grids of the radio frequency tubes to give automatic volume control. The first of these tubes has the grid and plate coupled together and acts as a true two-element rectifier, while the second has its grid directly coupled through a		resistance to the grid and plate of the first tube so that it fulfills the audio amplifying functions of a detector independently of the first tube. It is for this reason that we call the second tube a "detector amplifier" The first tube might be called a "detector rectifier" but we prefer to merely call it the "detector tube". Since it is a two-element rectifier it gives true linear detection without overloading on all signals impressed on it by the radio frequency amplifier"

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