Sparks Telegraph Key Review

The Sparks Telegraph Key Review

Spark Components

The Spark Components page is very much in its infancy and is expected to take several years before it is near completion. This list will be updated as additional information becomes available. It is currently a work in progress. Please e-mail me with information on spark components not yet included on this list. The Spark Components list will concentrate on the components that were specific or original to spark transmitters, but not including the keys and complete transmitters themselves since they are treated on the Spark Key Project and the Spark Transmitter Project.

A B C D E F G H I J K L M N P R S T U V W Y

Company Name Date Location Comments

ACME Apparatus Co. QST ad Nov/1920 Cambridge, MA Non-resonant transformers for high spark frequencies:
List No.12016 full power 250W
List No.12017 full power 500W
List No.12018 full power 1000W

ACME Wireless Construction Co. 1909 Cambridge, MA Probably same as ACME Apparatus Co. with older name.
Type A and Type B Helices & loading coils
Induction coils 1/2", 1", 1-1/2", 2"
Spark gaps
Type A, B & C transmitting condensers

Amalgamated Wireless Australasia 1913 Australia Formed from merger of Telefunken and Marconi interests in Australia.
Transmitting Helix
Plain Discharger (straight gap)

American Radio Sales & Service Co. QST ad July/1921 Mansfield, OH DX-52 Oscillation Transformer
DX-51 Spark Gap

AMRAD American Radio and Research Corporation QST ad November/1919 Medford Hillside, MA Lightning Switch 100A, 500V
Induction Coils:
Type C, 6 Volt
Type C1, 32 Volt

Quenched Gap
Type G-1 1 KW gap
Type G-2 1/2 KW gap
Type G-3 1/4 KW gap

Armorl (Armstrong-Orling) ? England "Induction coils in all sizes" up to 20"

Benwood Specialty Co. QST ad Dec/1919 St. Louis, MO "Benwood" Rotary Spark Gap
No.1 Benwood Gap complete
No.8 8 stud rotor
No.10 10 stud rotor
No.14 14 stud rotor

A.W. Bowman 1911-1922+ Lexington & Cambridge, MA Spark gap on 2-1/8" x 3-5/9" Bakelite base with name molded into it.

J.H. Bunnell & Co. ca 1915 New York Rotary and straight gaps sold under model names Beeko, Mascot, Dandy, and Jove
Spark Coil under brand name Mascot

F.B. Chambers & Co. QST ad Dec/1915 Phila., PA Rotary spark gaps, mahogany or marble bases
spark coil

Chelsea Radio Co. QST ad Aug/1920 Chelsea, MA Spark Load Coil (tapped loading inductance 0-3500 meters)

Chicago Radio Laboratory QST ad Nov/1919 Chicago, IL Hyrad synchronous rotary gap

Cino Radio Mfg. Co. QST ad Feb/1922 Cincinnati, Ohio "Cino Sink" rotary gap and motor

Clapp-Eastham began making radio equipment ca 1910 Cambridge MA Type Y 658 Antenna Switch (Oct/1920 QST ad)
Semi-Quenched Cambridge Rotating Discharger (rotary gap) from 8/1916 ad
Rotary Spark Gap No. 741 (QST ad Oct/1920)
Type F656 spark gap
Oscillation transformers:
No. Y-200 1/2 KW and up
No. TXL-101-A International, up to 1 KW
No. Y-100 up to 1/2 KW
Type 651 oscillation transformer
Type 653 "radiocoupler" oscillation transformer
Type Z642 protective device (2 condensers across line)
Type ZRL high tension transformer for use with rotary gaps
Type L spark transformer (1/4, 1/2, & 1 KW spark coil)
1/4, 1/2, 1, 2, & 3 KW Type E transformers (spark coil)
High potential condensers F654, F655, F655A, F655B, F655C
Type 611 electrolytic interrupter

Continental Electric Co. QST ad January/1920 New York, NY No. 1031 straight spark gap
Rotary spark gap

Doubleday-Hill Electric Co. QST ad April/1917 Pittsburgh, PA Rotary gap

Dubilier Condenser Company 1915 New York Founded by William Dubilier, and merged in 1933 with Cornell Electric.
CD 53 and CD 53A Spark Type Protective Device; capacity 150 amps, 500 volts for 1,2,5, and 10 KW spark sets.
Mica transmitting condensers (CD 54, etc.)

Wm. B. Duck Co. QST ad May/1917 Toledo, OH Some of these components probably only marketed by Duck and made by others.
Type "C" Sayville Gap (rotary gap, initially a Halcun product)
Type "D" Rotary spark gaps, in 1/2 KW and 1 KW rating
No.60X15A Zinc Spark Gap
No.60X15 Zinc Spark Gap
No.44X0 Spark Gap
No.A4018 Spark Gap with Porcelain Base
No.A4019 Standard Spark Gap with Porcelain Base (this made by J.H. Bunnell & Co.)
No.A395 Commercial Type Oscillation transformer
No.A7628 Oscillation transformer
No.A555 Junior Oscillation Transformer
No.39X0 1/4 inch spark coil
No.44X6 1 inch spark coil
No.40X0 1/2 inch spark coil
No.41X0 1.5" spark coil
No.42X0 2" spark coil
No.43X0 3" spark coil
No.44X0 4" spark coil
No.45X0 6" spark coil
Also offered "Bull Dog" type spark coils 1/4, 1/2, 1, 1-1/2, and 2" types
No.A560 Pancake Helix
High Voltage transformer in 1914 catalog, called a "Flexible step-up wireless transformer", adjustable by wingnut on top.
No.A1921 Solenoid Operated Antenna Switch
Flexible Step-Up Transformer No.63X0 (Type T-0), No.63X1 (Type T-1), No.63X2 (Type T-2), No.63X3 (Type T-3)
Rotary Spark Gap No.A442
Magnetic Key No.A1925
High Potential Condensers complete in rack (No.6051 to 6053, and No.A6100)
Model IX Glass Plate Condenser (No.A1923 and A1924)
1 KW Antenna Switch No.70X05
2 KW Antenna Switch No.70X06
Electrolytic Interruptor No.71X13 (parts individually can be ordered)

Ducretet 1899-1919 Paris, France Rotary Spark gap with rotating ball copper electrode

Economic Electric Co. 1909 or earlier? to about 1920 London, England Spark coils in at least 15 different spark lengths

Electric Machine Co. QST ad Nov/1920 Indianapolis, IN "Bell" Rotary Spark Gap

Electro Importing Company
EICo 1904-1915+ New York Components listed in the EICo Catalog 14, 1914:
Electro Zinc Spark Gap
Electro Commercial Spark Gap
Electro Sending Helix
Electro Commercial Oscillation Transformer
Electro Adjustable Sending Condenser
Electro Leyden Jars
Electro Adjustable High Tension Condensers
Electro 1/2 KW Transformer-Coil
Gernsback Electrolytic Interrupter
Electro Antenna Switch
Electro Wireless Lightning Switch
0.25 inch Bulldog spark coil dated 1912
0.5, 1.0 and 1.5 inch (Bulldog) spark coils (1914)
The "Electro" Rotary Spark Gap (1915)
The "Electro" Quenched Spark Gap (1915), 8 sections, capacity 1 KW

Electro-Set Co. 1914 Cleveland, OH 1/6 KW Closed Core High Tension Transformer
1/2, 3/4, and 1 KW Flexible Wireless Transformers
Electrolytic Interrupter
Electro-Set Box Type Spark Coils 1/8, 1/4, 1/2, 1, 2, 3 inch spark
No.801 Spark Gap
Senior Spark Gap
Electro-Set Special Air Cooled Spark Gap
Type "P" Rotary Spark Gap
Type "A" Rotary Spark Gap
Transmitting condensers
Leyden jars
No.606 Oscillation Helix for Small Stations
No.607 Loose coupled Oscillation Helix
No.610 Antenna Switch (for up to 1/2 kw)
No.611 Antenna Switch (for up to 1 kw)
No.612 Antenna Switch (for higher power)
No.615M Lightning Switch (60A rating)
No.616M Lightning Switch (100A rating)
No.617M Lightning Switch (100A, 600V rating)
Electro-Set Line Protector

Elliott Electric Co. QST ad May/1917 Shreveport, LA Rotary gap

J. Herbert Ferris QST ad Jan/1917 Royal Oak, MI Rotary Gap

Fisher 1919 ? 1 KW air cooled (cooling flanges) straight spark gap

Fosco Corp. QST ad Jan/1917 Chicago, IL "A-Motor" motor and aluminum rotary gap rotor

Franklin Sales Co. QST ad Oct/1920 Chicago, IL Franklin Rotary Spark Gap (Hamilton Beach Motor) 1/2 to 1 KW

A.H. Grebe & Co. QST ad June/1920 Richmond Hill, NY Type TGAC Synchronous Rotary Gap with 220V motor
Type TGAD Synchronous Rotary Gap with 110V motor
Both were also advertised by MESCO

Edward E. Hayward, Jr. QST ad May/1920 Boston, MA Little Wonder Gap, Rotary Gap.

The High Tension Co. 1916 Westminster, England Standard 12" spark coil
200 watt spark coil

Hunt & McCree 1917 NY Spark coils 1/4" to 10"

J-Ray M'F'G Co. QST ad Mar/1921 St. Louis, MO Rotary Spark Gap

Karlowa Radio Corp. QST ad Mar/1921 Rock Island, IL K20A (with Motor) and K20B (Pulley drive only) rotary gap

Kilbourne & Clark 1901-1920+ Seattle, WA Antenna switches for commercial and amateur use-- contacts arranged in the shape of a triangle on electrose insulators.

Fr. Klingelfuss & Co. 1903 Basel, Switzerland Spark coils for 10-150 cm spark length

Klitzen Wireless Apparatus Co. QST ad 1916 Racine, WI Klitzen Rotary Gap

Max Kohl A.G. 1909-1927+ Chemnitz, Germany Large induction coil

Lowenstein Radio Co. 1918, but drawings of Lowenstein keys as early as 1916 exist Brooklyn NY Type No. SE-994 1/2 KW Antenna Switch
Type No. SE 1499 1/2 KW Lightning Switch

Manhattan Electric Supply Co.
MESCO ca. 1910 New York Zinc straight spark gap List No.467 (by 1915)
"High Efficiency Spark Gap" List No.465 up to 1/4 KW capacity, hard rubber base and zinc terminals
Rotary spark gap (QST ad Dec/1915)
Spark coils in polished oak case with vibrator:
1/4", 1/2", 3/4", 1", 1-1/2", 2", 3", 4" operating on 5 dry cells, List Nos. 459-464, 495-6
Adjustable Primary condenser List No.439
Sending Helix No.484
Leyden Jars and Fixed Condensers
Antenna Switch List No.416
Antenna Switch List No.422
Improved Antenna Switch No.253 (looks like Clapp-Eastham Type Y 653)
Lightning Switch List No.384

Marconi 1899-1919
(Aldene, NJ plant mfg starts 1912) England, Canada, New York and New Jersey Type S H Antenna Switch
Type I antenna switch
Marconi Model 230 10" Spark Coil
Type B3 Transformer (1914)

From Marconi Catalog of Used Apparatus:
Motor Starter No.201
Motor Generator and disc discharger No.200, and No.214
Starting Switch No.202
2 KW 240-cycle transformer No.206
High Potential transformer No.216
High potential condenser No.207 and 218
Oscillation transformer No.208
Aerial Tuning Inductance No.209
Non-synchronous spark discharger No.220
Oscillation transformer No.221
Aerial changeover switch No.213

W.D. Mathews QST ad May/1920 Marlette, MI Improved Spark Gap

Mi-Kerm Radio Co. QST ad Sept/1921 Burlington, IA Mi-Kerm Rotary Quenched Spark Gap

Murdock, Wm.J. founded 1896 Chelsea, MA Beautiful oscillation transformer on wooden base. (No. 424)
Moulded Transmitting Condenser
No.440 Straight Spark Gap (1919) on hard rubber base

From April, 1910 catalog (transformers, condensers, spark gaps, and helices all in 1/4, 1/2, 1 & 2 KW sizes:

Transformers No.400, 110VAC 60 cycle with hard rubber pillars
Sending Condensers No.481, glass plate type, jar type on request
Straight Spark gaps No.441 on polished marble base
Helices No.421, copper ribbon
Antenna Switch No.462 on polished marble base
Sending Helix No. 420 wound with round copper wire

From 1913 catalog:
Transmitting Helix No.422
otherwise same as 1910

From 1920 catalog:
No.463 Antenna Switch
No.483 transmitting condenser
No.488 transmitting condenser
No.443 rotary spark gap
No.265, 266, 267 induction coils

Radiguet & Massiot 1906 Paris, France large & small size spark coils

Radio Apparatus Company of America QST ad Sept/1916 Phila., PA Hy-Tone Rotary spark gap

Radio Equipment Co. QST ad Feb/1921 Boston, MA Rotary Spark Gap

Radiolectric Shop ad QST Oct/1920 Cleveland, OH "73" single blade antenna switch, Type A with Marble base and Type B with wooden base

Radio Supply & Mfg. Co. QST ad May/1921 St. Paul, MI 4 or 8 tooth disc rotary gap

Ray-Di-Co QST ad Feb/1921 Chicago, IL Synchronous Rotary Gap

H.A. Reverend Mfg. Co. QST ad Feb/1917 Kansas City, MO Rotary Spark Gap

Saginaw Radio & Electric Co. QST ad July/1921 Saginaw, MI Sag-Re-Co products, "improved" spark gap with interchangeable teeth

Shotton Radio Manufacturing Co. QST ad Dec/1920 Scranton, PA "Shramco" Oscillation Transformer

Signal Electric Mfg. Co. QST ad Dec/1920 Menominee, MI "Signal Switch" Aerial changeover switch (QST ad 11/21)
"Signal" Rotary Spark Gap Motor

E.J. Simon 1915 New York CE 613 antenna switch and board

L. Brainerd Stratton QST ad Feb/1917 Oneida, NY The Monotone Quenched Gap

T & H Radio Co. QST ad June/1921 Anthony, KS Type TH-1 Oscillation Transformer, smaller ribbon on primary
Type TH-2 Oscillation Transformer, larger ribbon on primary

Telefunken QST ad April/1920 Germany Pancake Type Oscillation Transformer, marketed by Radio Equipment Co. of Phila.,PA

Thordarson Electric Mfg. Co QST ad March/1921 Chicago, IL Type R transformers 1 KVA, 0.75 KVA, 0.5 KVA
Type RS transformers 1 KVA, 0.5 KVA, 0.25 KVA
Oscillation transformer
Type T-OT Oscillation Transformer (QST ad Oct/1919)
8, 12, & 16 tooth rotary discs

Trumbull 1915 ? 100 Amp Ground Switch

Twin City Radio Lab. QST ad July/1921 St. Paul, MI The Arrow Disc "Spark-Thru" Type Rotary disc

United States Electrical Supply Co. 1900 New York Induction coil/gap for wireless telegraphy

WEACO Wireless Experimental Apparatus Co. QST ad Jan/1917 Phila., PA Rotary Gap

Western Radio Electric Co. QST ad Aug/1920 Los Angeles, CA WESRAD Oscillation Transformer designed for 200 meters, up to 1 KW

Wilcox Laboratories QST ad May/1920 Lansing, MI "Wilcox" Rotary Gap

Winn Radio & Electric Mfg. Co. QST ad June/1920 Chicago, IL "Winn" Transmitter Coil-- induction coil with interrupter, No. 210

Wireless Manufacturing Co. QST ad June/1920 Canton, OH Rotary Spark Gap

Wireless Specialty Apparatus Company 1907-1919 Boston, MA Components from 1919 Catalog:
Antenna Switch, Type Q-S-5001
Lightning Switch, Type Q-S-5002
Antenna Switch Type Q-S-501
Faradon condensers
Lightning Switch, Type Q-S-5007
Rotary Spark Gap, Type Q-S-5006

Young & McCombs QST ad Oct/1920 ? Young & McCombs Rotary Spark Gap

With assistance from Tom French, Doug Palmer, John Firey, Pete Malvasi, August Link, Chuck Brydges, Mike Feher, and many others!
Picture Credits:
Tom French-- Bowman gap
Pete Malvasi-- Murdoch oscillation transformer
Chuck Brydges-- 0.25 inch Bulldog spark coil
Mike Feher-- Marconi Type B3 Transformer

Russ Kleinman WA5Y
Last modified: January 10, 2005

FIRSTS! in the History of Wireless

Try guessing when you think the event on the left took place, then click on the event and the date will show to the right!

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Original Research Material at Sparks Telegraph Key Review
Sparks Telegraph Key Review Library

Company Name	Date	Location	Comments
ACME Apparatus Co.	QST ad Nov/1920	Cambridge, MA	Non-resonant transformers for high spark frequencies: List No.12016 full power 250W List No.12017 full power 500W List No.12018 full power 1000W
ACME Wireless Construction Co.	1909	Cambridge, MA	Probably same as ACME Apparatus Co. with older name. Type A and Type B Helices & loading coils Induction coils 1/2", 1", 1-1/2", 2" Spark gaps Type A, B & C transmitting condensers
Amalgamated Wireless Australasia	1913	Australia	Formed from merger of Telefunken and Marconi interests in Australia. Transmitting Helix Plain Discharger (straight gap)
American Radio Sales & Service Co.	QST ad July/1921	Mansfield, OH	DX-52 Oscillation Transformer DX-51 Spark Gap
AMRAD American Radio and Research Corporation	QST ad November/1919	Medford Hillside, MA	Lightning Switch 100A, 500V Induction Coils: Type C, 6 Volt Type C1, 32 Volt Quenched Gap Type G-1 1 KW gap Type G-2 1/2 KW gap Type G-3 1/4 KW gap
Armorl (Armstrong-Orling)	?	England	"Induction coils in all sizes" up to 20"
Benwood Specialty Co.	QST ad Dec/1919	St. Louis, MO	"Benwood" Rotary Spark Gap No.1 Benwood Gap complete No.8 8 stud rotor No.10 10 stud rotor No.14 14 stud rotor
A.W. Bowman	1911-1922+	Lexington & Cambridge, MA	Spark gap on 2-1/8" x 3-5/9" Bakelite base with name molded into it.
J.H. Bunnell & Co.	ca 1915	New York	Rotary and straight gaps sold under model names Beeko, Mascot, Dandy, and Jove Spark Coil under brand name Mascot
F.B. Chambers & Co.	QST ad Dec/1915	Phila., PA	Rotary spark gaps, mahogany or marble bases spark coil
Chelsea Radio Co.	QST ad Aug/1920	Chelsea, MA	Spark Load Coil (tapped loading inductance 0-3500 meters)
Chicago Radio Laboratory	QST ad Nov/1919	Chicago, IL	Hyrad synchronous rotary gap
Cino Radio Mfg. Co.	QST ad Feb/1922	Cincinnati, Ohio	"Cino Sink" rotary gap and motor
Clapp-Eastham	began making radio equipment ca 1910	Cambridge MA	Type Y 658 Antenna Switch (Oct/1920 QST ad) Semi-Quenched Cambridge Rotating Discharger (rotary gap) from 8/1916 ad Rotary Spark Gap No. 741 (QST ad Oct/1920) Type F656 spark gap Oscillation transformers: No. Y-200 1/2 KW and up No. TXL-101-A International, up to 1 KW No. Y-100 up to 1/2 KW Type 651 oscillation transformer Type 653 "radiocoupler" oscillation transformer Type Z642 protective device (2 condensers across line) Type ZRL high tension transformer for use with rotary gaps Type L spark transformer (1/4, 1/2, & 1 KW spark coil) 1/4, 1/2, 1, 2, & 3 KW Type E transformers (spark coil) High potential condensers F654, F655, F655A, F655B, F655C Type 611 electrolytic interrupter
Continental Electric Co.	QST ad January/1920	New York, NY	No. 1031 straight spark gap Rotary spark gap
Doubleday-Hill Electric Co.	QST ad April/1917	Pittsburgh, PA	Rotary gap
Dubilier Condenser Company	1915	New York	Founded by William Dubilier, and merged in 1933 with Cornell Electric. CD 53 and CD 53A Spark Type Protective Device; capacity 150 amps, 500 volts for 1,2,5, and 10 KW spark sets. Mica transmitting condensers (CD 54, etc.)
Wm. B. Duck Co.	QST ad May/1917	Toledo, OH	Some of these components probably only marketed by Duck and made by others. Type "C" Sayville Gap (rotary gap, initially a Halcun product) Type "D" Rotary spark gaps, in 1/2 KW and 1 KW rating No.60X15A Zinc Spark Gap No.60X15 Zinc Spark Gap No.44X0 Spark Gap No.A4018 Spark Gap with Porcelain Base No.A4019 Standard Spark Gap with Porcelain Base (this made by J.H. Bunnell & Co.) No.A395 Commercial Type Oscillation transformer No.A7628 Oscillation transformer No.A555 Junior Oscillation Transformer No.39X0 1/4 inch spark coil No.44X6 1 inch spark coil No.40X0 1/2 inch spark coil No.41X0 1.5" spark coil No.42X0 2" spark coil No.43X0 3" spark coil No.44X0 4" spark coil No.45X0 6" spark coil Also offered "Bull Dog" type spark coils 1/4, 1/2, 1, 1-1/2, and 2" types No.A560 Pancake Helix High Voltage transformer in 1914 catalog, called a "Flexible step-up wireless transformer", adjustable by wingnut on top. No.A1921 Solenoid Operated Antenna Switch Flexible Step-Up Transformer No.63X0 (Type T-0), No.63X1 (Type T-1), No.63X2 (Type T-2), No.63X3 (Type T-3) Rotary Spark Gap No.A442 Magnetic Key No.A1925 High Potential Condensers complete in rack (No.6051 to 6053, and No.A6100) Model IX Glass Plate Condenser (No.A1923 and A1924) 1 KW Antenna Switch No.70X05 2 KW Antenna Switch No.70X06 Electrolytic Interruptor No.71X13 (parts individually can be ordered)
Ducretet	1899-1919	Paris, France	Rotary Spark gap with rotating ball copper electrode
Economic Electric Co.	1909 or earlier? to about 1920	London, England	Spark coils in at least 15 different spark lengths
Electric Machine Co.	QST ad Nov/1920	Indianapolis, IN	"Bell" Rotary Spark Gap
Electro Importing Company EICo	1904-1915+	New York	Components listed in the EICo Catalog 14, 1914: Electro Zinc Spark Gap Electro Commercial Spark Gap Electro Sending Helix Electro Commercial Oscillation Transformer Electro Adjustable Sending Condenser Electro Leyden Jars Electro Adjustable High Tension Condensers Electro 1/2 KW Transformer-Coil Gernsback Electrolytic Interrupter Electro Antenna Switch Electro Wireless Lightning Switch 0.25 inch Bulldog spark coil dated 1912 0.5, 1.0 and 1.5 inch (Bulldog) spark coils (1914) The "Electro" Rotary Spark Gap (1915) The "Electro" Quenched Spark Gap (1915), 8 sections, capacity 1 KW
Electro-Set Co.	1914	Cleveland, OH	1/6 KW Closed Core High Tension Transformer 1/2, 3/4, and 1 KW Flexible Wireless Transformers Electrolytic Interrupter Electro-Set Box Type Spark Coils 1/8, 1/4, 1/2, 1, 2, 3 inch spark No.801 Spark Gap Senior Spark Gap Electro-Set Special Air Cooled Spark Gap Type "P" Rotary Spark Gap Type "A" Rotary Spark Gap Transmitting condensers Leyden jars No.606 Oscillation Helix for Small Stations No.607 Loose coupled Oscillation Helix No.610 Antenna Switch (for up to 1/2 kw) No.611 Antenna Switch (for up to 1 kw) No.612 Antenna Switch (for higher power) No.615M Lightning Switch (60A rating) No.616M Lightning Switch (100A rating) No.617M Lightning Switch (100A, 600V rating) Electro-Set Line Protector
Elliott Electric Co.	QST ad May/1917	Shreveport, LA	Rotary gap
J. Herbert Ferris	QST ad Jan/1917	Royal Oak, MI	Rotary Gap
Fisher	1919	?	1 KW air cooled (cooling flanges) straight spark gap
Fosco Corp.	QST ad Jan/1917	Chicago, IL	"A-Motor" motor and aluminum rotary gap rotor
Franklin Sales Co.	QST ad Oct/1920	Chicago, IL	Franklin Rotary Spark Gap (Hamilton Beach Motor) 1/2 to 1 KW
A.H. Grebe & Co.	QST ad June/1920	Richmond Hill, NY	Type TGAC Synchronous Rotary Gap with 220V motor Type TGAD Synchronous Rotary Gap with 110V motor Both were also advertised by MESCO
Edward E. Hayward, Jr.	QST ad May/1920	Boston, MA	Little Wonder Gap, Rotary Gap.
The High Tension Co.	1916	Westminster, England	Standard 12" spark coil 200 watt spark coil
Hunt & McCree	1917	NY	Spark coils 1/4" to 10"
J-Ray M'F'G Co.	QST ad Mar/1921	St. Louis, MO	Rotary Spark Gap
Karlowa Radio Corp.	QST ad Mar/1921	Rock Island, IL	K20A (with Motor) and K20B (Pulley drive only) rotary gap
Kilbourne & Clark	1901-1920+	Seattle, WA	Antenna switches for commercial and amateur use-- contacts arranged in the shape of a triangle on electrose insulators.
Fr. Klingelfuss & Co.	1903	Basel, Switzerland	Spark coils for 10-150 cm spark length
Klitzen Wireless Apparatus Co.	QST ad 1916	Racine, WI	Klitzen Rotary Gap
Max Kohl A.G.	1909-1927+	Chemnitz, Germany	Large induction coil
Lowenstein Radio Co.	1918, but drawings of Lowenstein keys as early as 1916 exist	Brooklyn NY	Type No. SE-994 1/2 KW Antenna Switch Type No. SE 1499 1/2 KW Lightning Switch
Manhattan Electric Supply Co. MESCO	ca. 1910	New York	Zinc straight spark gap List No.467 (by 1915) "High Efficiency Spark Gap" List No.465 up to 1/4 KW capacity, hard rubber base and zinc terminals Rotary spark gap (QST ad Dec/1915) Spark coils in polished oak case with vibrator: 1/4", 1/2", 3/4", 1", 1-1/2", 2", 3", 4" operating on 5 dry cells, List Nos. 459-464, 495-6 Adjustable Primary condenser List No.439 Sending Helix No.484 Leyden Jars and Fixed Condensers Antenna Switch List No.416 Antenna Switch List No.422 Improved Antenna Switch No.253 (looks like Clapp-Eastham Type Y 653) Lightning Switch List No.384
Marconi	1899-1919 (Aldene, NJ plant mfg starts 1912)	England, Canada, New York and New Jersey	Type S H Antenna Switch Type I antenna switch Marconi Model 230 10" Spark Coil Type B3 Transformer (1914) From Marconi Catalog of Used Apparatus: Motor Starter No.201 Motor Generator and disc discharger No.200, and No.214 Starting Switch No.202 2 KW 240-cycle transformer No.206 High Potential transformer No.216 High potential condenser No.207 and 218 Oscillation transformer No.208 Aerial Tuning Inductance No.209 Non-synchronous spark discharger No.220 Oscillation transformer No.221 Aerial changeover switch No.213
W.D. Mathews	QST ad May/1920	Marlette, MI	Improved Spark Gap
Mi-Kerm Radio Co.	QST ad Sept/1921	Burlington, IA	Mi-Kerm Rotary Quenched Spark Gap
Murdock, Wm.J.	founded 1896	Chelsea, MA	Beautiful oscillation transformer on wooden base. (No. 424) Moulded Transmitting Condenser No.440 Straight Spark Gap (1919) on hard rubber base From April, 1910 catalog (transformers, condensers, spark gaps, and helices all in 1/4, 1/2, 1 & 2 KW sizes: Transformers No.400, 110VAC 60 cycle with hard rubber pillars Sending Condensers No.481, glass plate type, jar type on request Straight Spark gaps No.441 on polished marble base Helices No.421, copper ribbon Antenna Switch No.462 on polished marble base Sending Helix No. 420 wound with round copper wire From 1913 catalog: Transmitting Helix No.422 otherwise same as 1910 From 1920 catalog: No.463 Antenna Switch No.483 transmitting condenser No.488 transmitting condenser No.443 rotary spark gap No.265, 266, 267 induction coils
Radiguet & Massiot	1906	Paris, France	large & small size spark coils
Radio Apparatus Company of America	QST ad Sept/1916	Phila., PA	Hy-Tone Rotary spark gap
Radio Equipment Co.	QST ad Feb/1921	Boston, MA	Rotary Spark Gap
Radiolectric Shop	ad QST Oct/1920	Cleveland, OH	"73" single blade antenna switch, Type A with Marble base and Type B with wooden base
Radio Supply & Mfg. Co.	QST ad May/1921	St. Paul, MI	4 or 8 tooth disc rotary gap
Ray-Di-Co	QST ad Feb/1921	Chicago, IL	Synchronous Rotary Gap
H.A. Reverend Mfg. Co.	QST ad Feb/1917	Kansas City, MO	Rotary Spark Gap
Saginaw Radio & Electric Co.	QST ad July/1921	Saginaw, MI	Sag-Re-Co products, "improved" spark gap with interchangeable teeth
Shotton Radio Manufacturing Co.	QST ad Dec/1920	Scranton, PA	"Shramco" Oscillation Transformer
Signal Electric Mfg. Co.	QST ad Dec/1920	Menominee, MI	"Signal Switch" Aerial changeover switch (QST ad 11/21) "Signal" Rotary Spark Gap Motor
E.J. Simon	1915	New York	CE 613 antenna switch and board
L. Brainerd Stratton	QST ad Feb/1917	Oneida, NY	The Monotone Quenched Gap
T & H Radio Co.	QST ad June/1921	Anthony, KS	Type TH-1 Oscillation Transformer, smaller ribbon on primary Type TH-2 Oscillation Transformer, larger ribbon on primary
Telefunken	QST ad April/1920	Germany	Pancake Type Oscillation Transformer, marketed by Radio Equipment Co. of Phila.,PA
Thordarson Electric Mfg. Co	QST ad March/1921	Chicago, IL	Type R transformers 1 KVA, 0.75 KVA, 0.5 KVA Type RS transformers 1 KVA, 0.5 KVA, 0.25 KVA Oscillation transformer Type T-OT Oscillation Transformer (QST ad Oct/1919) 8, 12, & 16 tooth rotary discs
Trumbull	1915	?	100 Amp Ground Switch
Twin City Radio Lab.	QST ad July/1921	St. Paul, MI	The Arrow Disc "Spark-Thru" Type Rotary disc
United States Electrical Supply Co.	1900	New York	Induction coil/gap for wireless telegraphy
WEACO Wireless Experimental Apparatus Co.	QST ad Jan/1917	Phila., PA	Rotary Gap
Western Radio Electric Co.	QST ad Aug/1920	Los Angeles, CA	WESRAD Oscillation Transformer designed for 200 meters, up to 1 KW
Wilcox Laboratories	QST ad May/1920	Lansing, MI	"Wilcox" Rotary Gap
Winn Radio & Electric Mfg. Co.	QST ad June/1920	Chicago, IL	"Winn" Transmitter Coil-- induction coil with interrupter, No. 210
Wireless Manufacturing Co.	QST ad June/1920	Canton, OH	Rotary Spark Gap
Wireless Specialty Apparatus Company	1907-1919	Boston, MA	Components from 1919 Catalog: Antenna Switch, Type Q-S-5001 Lightning Switch, Type Q-S-5002 Antenna Switch Type Q-S-501 Faradon condensers Lightning Switch, Type Q-S-5007 Rotary Spark Gap, Type Q-S-5006
Young & McCombs	QST ad Oct/1920	?	Young & McCombs Rotary Spark Gap