One Tube Radio

Brooke Clarke 2010 - 2023

One Tube Radio WD-11 Armstrong

Edwin Howard Armstrong
Lee De Forest
Tube History
    UV-201 Tube
    Charles Eisler
Reflex Receiver
Battery Eliminators
Unipotential Tubes


After Crystal Radios, that have no tubes and don't require any power other than the received signal, the next level of complexity is the one tube radio.  It uses a regenerative circuit (Wiki) to get more gain from the single WD-11 (Wiki) tube.
(2014) The below schematic has an error.  The Volume pot is in the filament circuit not the B+ circuit.
            Receiver schematic

Edwin Howard Armstrong (Wiki, EROLS)

The popular inventor of the regenerative receiver as well as FM radio.

Lee De Forest (Wiki)

Patented the regenerative receiver prior to Armstrong and won the court battle over it.  But De Forest was involved in a number of shady deals where he was sued and lost so although he really did invent the regenerative radio receiver seldom gets full credit.


The major components are:
Variometer coil with 6 taps - top center dial rotates internal coil, lower center switch selects taps.  The movable coil controls the regeneration.
6 Position Switch - controls the tuned frequency along with the variable cap.
Filament Rheostat - controls tube emission (early tube had wide varations in their gain.
Marked C-H Patent Applied For
It has two concentric shafts and two knobs, a coarse and fine knob.
Only two electrical terminals.
1672290 Potential-Control Apparatus, H.J. Wiegand (Cuttler-Hammer Mfg Co), Jun 5 1928, 338/134 ; 338/150 -
for regulating the plate and filament voltages on audion valves
Variable Capacitor - knob on left tuns capacitor, stations
Radiola WD tube socket - for WD-11 or equivalent tube.
1516837 Thermionic-tube Adapter, C.F Wright (Wireless Specialty Apparatus Co), Nov 25 1924 (filed Apr 4 1923), 439/655
specifically for using the UV 199 to replace the WD 11.
1696406 Radio Tube Socket, F.S. Masley & A.P. Wasil, Dec 25 1928, 439/573- specifically for the WD-11.
1913766 Method and Apparatus for Testing Audion Tube Circuits and Devices, J.H. Miller, Jun 13 1933, - Tube Tester
3 Meg Ohm resistor in a cylindrical glass holder very similar to a glass fuse except it has points on the ends to fit into the clip holder.
8 Terminals (2 more terminals used for internal wire connections)
1 & 2: Phones
3 & 4: Antenna and Ground
5 & 6 Filament "A" battery (at rear)
7 & 8: Plate "B" battery (at rear)

One Tube Radio

One Tube Radio


The terminals are arranged to match the physical location.  This is the Armstrong regenerative circuit.  The plate is connected to the phones then the variable tickler coil.
It's not clear if the antenna and ground are reversed.  The metal on the back of the front panel is connected to the upper terminal.

                Tube Radio schematic



Class Numbers

Class 329 Demodulators
    347 AM
        367 Including regenerative feedback in non-oscillating demodulator
Class 375 Pulse or Digital Communications
    316 Receivers
        338 Interrupted Carrier Wave
            339 Carrier Controlling Local Generator
Class 455 Telecommunications,
    130 Receiver or Analog Modulated Signal Frequency Converter,
        334 With particular receiver circuit,
            336 Super-regenerative detector or discriminator

803684 Instrument for converting alternating electric currents into continuous currents, John Ambrose Fleming, Marconi Wireless Telegraph Co, 1905-11-07, - diode tube
841387 Device for amplifying feeble electrical currents, Lee De Forest, 1907-01-15, - triode & other stuff
879532 Space Telegraphy, Lee De Forest, Feb 18 1908, 329/368 ; 313/293; 315/355; 336/220 - Triode Vacuum Tube called an Audion at the time.
Has elements called the filament, grid and plate (in later patents called the wing).

1507016 Radio Signaling System, Lee De Forest, Sep 2 1924, 178/118 ; 331/171 - "kick-back" & progressive amplification mentioned (i.e. feedback)
1507017 Wireless Telegraph and Telephone System, Lee De Forest, Sep 2 1924, 370/339 -
There was a lawsuit between De Forest and Armstrong and De Forest won the suit (The Complete De Forest- Litigation)
Lee De Forest
            patent 1507016 Regenerative Radio Receiver

1113149 Wireless Receiving System, Edwin H. Armstrong, Oct 6 1914, 375/339 ; 329/359; 455/321 -
Being in class 375 is interesting
The 1923 Crosley Harko ACE is marked "Manufactured under Armstrong U.S. patent 1113149" as is the Crosley Model 51.
Armstrong patent 1113149 Fig 6
              Regenerative Receiver
1381692 Device for Receiving Radiotelegraphic and Radiotelephonic Signals, Cesare Bardeloni, June 14 1921 (filed April 12 1919), -
Oldest patent in class 455/336
                1381692 Fig 6 by Cesare Bardeloni
1342885 Method of Receiving High-Frequency Oscillations, E. H. Armstrong, June 8 1920, 455/315 ; 330/165; 455/331
1415845 Selectively Opposing Impedance to Received Electrical Oscillations, M.I. Pupin & E. H. Armstrong, May 9 1922, 455/282 -
1416061 Radoreceiving System having High Selectivity, M.I. Pupin & E. H. Armstrong, May 16 1922, 375/338 ; 307/105 -
1424065 Signaling System, E. H. Armstrong, July 25 1922 (filed June 27 1921), 455/336 ; 329/359; 329/368; 329/370 -
Called  Regenerative in this patent, but super regenerative in patent 1539821.
Second oldest patent in class 455/336
                patent 1424065 Fig 10
1472092 Receiver for Wireless Telegraphy, RCA, Oct 30 1923, 455/286 ; 455/290; 455/312; 455/315
1539821 Wave Signaling System, E. H. Armstrong (Westinghouse Elec),  June 2 1925, 455/336 - two tube adjustable Super Regenerative
1611848 Wireless Receiving system for Continuous Waves, E. H. Armstrong (Westinghouse Elec), Dec 21 1926, 375/338 -
1502875 Tone Producing Radioreceiver, M.I. Pupin & E. H. Armstrong (Westinghouse Elec), July 29 1924, 375/339 -

1472583 Method of Maintaining Electyric Currents of Constant Frequency, W.G. Cady (RCA), Oct 30 1923, 331/163 ; 330/112; 331/158; 331/159; 331/164
RE17247 Method of Maintaining Electyric Currents of Constant Frequency, W.G. Cady (RCA), May 26 1929, 331/164 ; 310/318; 333/188 -
Fig 1 is the Armstrong circuit.
RCA patent
              1472583 Fig 1 Armstrong regenerative radio
RCA 1922 Radiola Senior one tube radio patent dates:
1922 Radiola
              Senior schematic diagram
Nov 7, 1905
Jan 15, 1907
Feb 18, 1908
Oct 6, 1914
May 10, 1921
Given the list of patent dates above the following may be the corresponding patents:
803569 Induction-Transformer for Wireless-Telegraphy Receiving-stations, Eugene Ducretet, Nov 7 1905, 455/292 - uses coherer and battery (not tube) -although not a regenerative radio, it's very close to the circuit,
804190 Instrument for Making Electrical Measurements, J.A. Fleming (Marconi), Nov 7 1905, - not the circuit, but interesting
841386 Wireless Telegraphy, Lee De Forest, Jan 15, 1907, 315/94 ; 313/147; 313/152; 313/157; 313/161; 313/581; 315/348; 315/349; 315/357; 329/322 - one tube
879532 Space Telegraphy, Lee De Forest, Feb 18 1908, -329/368 ; 313/293; 315/355; 336/220  one tube radio without feedback
1113149 Oct 6, 1914 (see 1113149 Armstrong patent above)
1377405 Audion Circuit, Lee De Forest (De Forest Radio Telephone & Telegraph), May 10 1921, 330/103 ; 330/109; 330/185 - dual triode with feedback


Brooke's Crystal Radio Info
Brooke"s High Q Crystal Radio
Goof  Proof Regenerative Receiver, 73's Nov 1990 - PCB from FAR Circuits
ARRL - High Performance Regenerative Receiver Design by Charles Kitchin, N1TEV, QEX Nov/Dec 1998, pg 24-36 - PCB from FAR Circuits
The New Radio Receiver Building Handbook by Lyle Russell Williams
4 Pin to 7/9 Pin Adapter Kits - allow using a 7 or 9 pin standard glass tube.
Substitutes for the WD-11 - with 4-pin base drawing

Tube History

Wiki: Vacuum Tube History and Development
This comes from the paper:A History of U.S. Navy Periscope Detection Radar: Sensor Design and Development, Shannon & Moser, 2014.
Also see Periscope.

UV-201 Tube

Patent Dates from Radiotron UV-201 box.  Manufactured by Westinghouse for RCA.


841387 Device for amplifying feeble electrical currents, Lee De Forest, 1907-01-15, -

879532 - Audion

954619 Instrument for detecting electric oscillations, John Ambrose Fleming, Marconi Wireless, 1910-04-12, -

1018500 Forming device for metallic filaments, Henry W Jackson, Westinghouse Lamp Co, 1912-02-27, -





1203495 Vacuum-tube, William D Coolidge, General Electric, 1916-10-31, - X-Ray







Patent dates from a WD-11 box.  I suspect not of them are applicable to the WD-11, but some might be.  They are Westinghouse patents up to 1919.














After looking at some of the comments in the book Chip War by Chris Miller I'm adding some information here.

                      Electrical Indicator, Thomas A. Edison, Oct 21,

307031 Electrical Indicator, Thomas A. Edison, Oct 21, 1884

Adds another electrode to an electric lamp and notices how it works.

First patent for an electronic device.

I have discovered that if a conducting substance is interposed anywhere in the vacuous space within the globe of an incandescent electric lamp, and said conducting substance is connected outside of the lamp with one terminal, preferably the positive one, of the incandescent conductor, a portion of the current will, when the lamp is in operation, pass through the shunt-circuit thus formed, which shunt includes a portion of the vacuous space within the lamp, This current I have found to be proportional to the degree of incandescence of the conductor or candle-power of the lamp."

The anode current depends on the filament power.  Note in vacuum tubes the filament power needs to be about the same as the anode power.  So one of the big advantages of the transistor is that is has no filament and so can be about twice as efficient as a vacuum tube.

Note 1884 is prior to the 1888 early patents on commercial electrical meters hence the home brew looking meter in this patent.
                      Instrument for converting alternating electric
                      currents into continuous currents, John Ambrose
                      Fleming, Marconi Wireless
803684 Instrument for converting alternating electric currents into continuous currents, John Ambrose Fleming, Marconi Wireless Telegraph Company Of America, Filed:  Pub: Nov 7, 1905 - this patent is for a radio telegraph receiving device.

Fleming Valve (rectifier)

879532 Space
                      telegraphy, Lee De Forest
879532 Space telegraphy, Lee De Forest, Forest Radio Telephone Co, Feb 18, 1908  

De Forest adds a grid to the tube and calls it the Audion.  His two prior patents 824637 & 836070 used Fleming valves (i.e. no grid).
924560 Wireless
                      signaling system, Guglielmo Marconi, Marconi
924560 Wireless signaling system, Guglielmo Marconi, Marconi Wireless Telegraph Company Of America, Jun 8, 1909    
1608313 Method
                      of and means for producing alternating currents,
                      Hull Albert W, Gen Electric - Magnetron
1608313 Method of and means for producing alternating currents, Hull Albert W, Gen Electric, Nov 23, 1926

two-pole magnetron (15 kW @ 20 kHz)
Gets around prior patents by using magnetic filed to control tube current.
                      High-frequency-electrical oscillator, Howard Boot
                      Henry Albert, Turton Randall John, English
                      Electric Valve Co Magnetron
2542966 High-frequency-electrical oscillator, Howard Boot Henry Albert, Turton Randall John, English Electric Valve Co Ltd, Priority: Aug 22, 1940, Pub: Feb 20, 1951 water cooled magnetron 
5 designs shown, 4 of which have power outputs of (kW):
Pwr Out (kW)
150 5-10 5-10 10-15 na

Output at X-band (1.9 cm) is very low.

Charles Eisler

The Book "The Million Dollar Bend" ( brought him to me attention.  He made manufacturing equipment used for making glass envelopes for radio tubes and lamps as well as other equipment related used by radio manufacturers.   Instead of pulling a vacuum on the tube/lamp from the top, leaving a "tip" on the top, the vacuum is pulled out the bottom.
He holds about 55 patents.

Patents mentioned and illustrated in appendix (pg 262) and listed on page 311.

1209650 Turret attachment for machine-tools, Eisler Charles, 1916-12-19, - to allow normal lathe or drill press to have turret (chucker)  lathe capabilities.

1246250 Adjustable drill-head, Eisler Charles, 1917-11-13, - Dual heads drill 2 holes at same time.

1309616 Sheet-metal device, Eisler Charles, 1919-07-15, - sheet metal nut: cap, wing, acorn

1324886 Means for Increasing the Efficiency of Swaging Machines, Eisler Charles, Westinghouse Lamp Co,1919-12-16 -

1338498 Filament-winding machine, Eisler Charles, Westinghouse Lamp Co, 1920-04-27, -

1338499 Machine for making filament-supports for incandescent lamps, Eisler Charles, Westinghouse Lamp Co, 1920-04-27, - "button press" 30,000 double buttons per day

1338500 Machine for making incandescent-lamp stems, Eisler Charles, Westinghouse Lamp Co, 1920-04-27, -

1522001 Head for constructing incandescent electric-lamp stems, Eisler Charles, 1925-01-06, - 

1553309 Universal filament-coil-winding machine, Eisler Charles, 1925-09-15, -

1635316 Machine for making radio tube and lamp parts, Eisler Charles,1927-07-12, -

1637989 Machine for making glass mounts, Eisler Charles, 1927-08-02, -

1655050 Sealing-in machine for tubes and bulbs,  Eisler Charles, 1928-01-03, -

1704359 Ribbon Gas Burner, Eisler Charles, 1929-03-05, -  - neon signs w/quick shutoff
                        Construction of incandescent lamps, Ray
                        Frederick, Charles Eisler, 1929-02-12 1701541 Construction of incandescent lamps, Ray Frederick, Charles Eisler, 1929-02-12, -

1828493 Disk valve for burners, Eisler Charles, Eisler Electric, 1931-10-20, -

1866634 Bead Machine, Charles Eisler,

1936426 Sealing-off and dumping mechanism for exhaust machines, Eisler Charles, Eisler Electric, 1933-11-21, -

2006544 Welding machine, Eisler Charles, Eisler Engineering Co, 1935-07-02, - Spot

2063235 Sealing machine, Eisler Charles, 1936-12-08, -

2078630 Machine for making coils of wire, Eisler Charles, 1937-04-27, -

2231617 Welding machine, Eisler Charles, 1941-02-11, - Spot

2410931 Tube cracking machine, Eisler Charles,1946-11-12, - for fluorescent lamp tubes.

2413960 Machine for sealing glass bulbs, Eisler Charles, 1947-01-07, -

2414587 Machine for piercing glass bulbs, Eisler Charles, 1947-01-21, - for 1 or 2  electrical caps

2418763 Machine for sealing and molding glass bulbs, Eisler Charles, 1947-04-08, -

2421929 Machine for sealing bulbs, Eisler Charles, 1947-06-10, -

2446000 Machine for flanging glass blanks, Eisler Charles, 1948-07-27, - Syringe tip-forming machine

2779135 Tube shrinking machine, Eisler Charles, 1957-01-29, - Syringe

2783531 Work holder turntable mechanism, Eisler Charles, 1957-03-05, - used for arc welding

Reflex Receiver

In a Reflex Receiver (Wiki) same tube is used to amplify both the radio MF signal and the audio signal.  The photos and schematic were provided by Al.

Fig 1 Front Panel
Fig 2 Inside UV201 Tube
Upper Left AF trans.    Upper right RF trans.
Fig 3 Schematic


1087892 Means
                      for receiving electrical oscillations, Wilhelm
                      Schloemilch, Otto V Bronk, 1914-02-17
1087892 Means
                      for receiving electrical oscillations, Wilhelm
                      Schloemilch, Otto V Bronk, 1914-02-17 1087892 Means for receiving electrical oscillations, Wilhelm Schloemilch, Otto V Bronk, 1914-02-17, -

Fig 1, Fig 2 & Fig 3 prior art.
Fig 4 Reflex Receiver
Audio Transformer (o)
MF Transformer (k)
Note B+ Battery (i) is shown as a generator, whereas filament battery (b) is shown as a battery.
also note capacitors use units of cm rather than Farads. See Tesla.

1735185 Radio Receiver, Schaffer Walter, Telefunken AG, 1929-11-12, - still works if tube fails.

2205243 Amplifier, Robert B Dome, GE, 1940-06-18, - for use in TV IF

2777056 Reflex circuit for amplifying intermediate and detected video frequencies in same stage, Richard W Bull, 1957-01-08, - for use in TV IF stage.

2863066 Reflex circuit system, Witt David De, Sandler Harold, Roland C Wittenberg, Radio Receptor Co, 1958-12-02, - single PNP transistor

Battery Eliminators

Galvin Mfg Co got their start making these, so I was hoping to find some patents.

1682492 Radio battery eliminator, Philip E Edelman, 1928-08-28, -

1742682 Battery eliminator, Roland F Beers, Raytheon, 1930-01-07, -

1758947 Battery eliminator, Hammond Laurens, Andrews Hammond Corp, 1930-05-20, -

2208933 Battery eliminator, Loewenhaupt Emil, Telefunken AG, 1940-07-23, -

Unipotential Tubes

These tubes do not need high voltage (B+).  Instead they use a voltage for the plate supply that's the same as the voltage used to heat the filament.
Learned about these (aka: Space Charge tubes) in the same YouTube video as the above battery eliminators: Fun, Fun, Fun - The History of Car Radios, 56:45 -
@ 34:59: Unipotential Tubes: 12EK6, 12BL6, 12EH5, 6CQ8, 12DL8, 12AD6, 12K5, 12AE6A, 12BK5, 12BL6, 12AF6, 12BL6, 12CA5, ...


NBS Circular 120: article about Construction and Operation of a Simple Homemade Radio Receiving Outfit (pdf) - Circular 120 (pdf)
RCA Radiola III and III-A By Doug Criner - includes info on WD-11 tube substitutions
Dialcover by Bill Turner - parts and manuals
1922 Radiola Senior -

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