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unknown Spark Transmitter

unknown Spark Transmitter ; Unknown Worldwide (ID = 1489865) Morse+TTY unknown Spark Transmitter ; Unknown Worldwide (ID = 1489871) Morse+TTY
unknown Spark Transmitter ; Unknown Worldwide (ID = 1489036) Morse+TTY unknown Spark Transmitter ; Unknown Worldwide (ID = 1489870) Morse+TTY
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unknown Spark Transmitter ; Unknown Worldwide (ID = 1489865) Morse+TTY
Unknown Worldwide: unknown Spark Transmitter [Morse+TTY] ID = 1489865 480x640
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For model unknown Spark Transmitter, Unknown Worldwide
Country:  Worldwide
Manufacturer / Brand:  Unknown Worldwide
Year: 1900 ?? Category: Morse-Equipment & TTY, RTTY, TDD etc.
Main principle Transmitter
Power type and voltage Storage and/or dry batteries / 6-12 Volt
Power out 1 W (unknown quality)
from Model: unknown Spark Transmitter - Unknown Worldwide
Shape Miscellaneous shapes - described under notes.
Dimensions (WHD) 130 x 200 x 130 mm / 5.1 x 7.9 x 5.1 inch

This small spark transmitter was probably used at ships as a test signal to adjust the receiver detectors. It does not have a resonating circuit but can be connected to a resonating antenna just as the Marconi emergency transmitters. The power though is too small to be a communication unit. When connected at a 1 MHz resonating circuit with 1000 pF capacitor, the peak power is approx. 2 kW and the avarage power is approx. 1 Watt with a pulse repetition frequency of 100 Hz. connected at a 6V lead acid battery.

The body is carton holding the coils completely potted with bees wax. The base is heavy stone nicely elaborated.

Net weight (2.2 lb = 1 kg) 3.1 kg / 6 lb 13.3 oz (6.828 lb)

Model page created by Nicolaas van Dijk. See "Data change" for further contributors.

All listed radios etc. from Unknown Worldwide
Here you find 716 models, 648 with images and 22 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Unknown Worldwide: unknown Spark Transmitter
Threads: 1 | Posts: 10
Hits: 2009     Replies: 9
unknown: unknown Spark Transmitter
Nicolaas van Dijk

 I uploaded foto's from a small unknown spark transmitter with some information in  page with id 238588.

I did try to put the link in this text, but was unable to do that. Typing it does not work

The transmitter may be a signal source used at ships to adjust the detectors of the receiver. The power is too small for being a communication unit. Connected at 6 volts and connected at a 1 MHz resonance circuit with a 1000 pF capacitor, the avarage power is approx. 1 Watt while the peak power is approx 2 kW

Is there someone that can give some more information about this device?

Kind regards




Nikolaus Löwe

This beautifully designed Ruhmkorff induction coil with integrated interrupter and Morse key looks to me like one of the sets sold around 1900 for demonstration of wireless telegraphy by Hertzian waves. If so, it was likely meant to be operated with a plain aerial and earth and no tuned circuit. This was the way the first Marconi sets worked. A suitable coherer receiver can be seen here, another very elaborate set here and here. The latter unit already uses tuned circuits.

The matching receivers employed a coherer, that is a voltage detecting element whose ohmic resistance decreases when triggered by a voltage of about 0.5 Volts. As the impulses from a spark transmitter have extremely high peaks, like the 2kW you have measured on your set, coherer reception was in fact operational over considerable distances.

The coherer was superseded by magnetic detectors, electrolytic detectors, and then crystal and valve detectors.

I have added the very simple schematic of a transmitter of this type, and a photograph of Signor Marconi with a complete station. On the right there is a large induction coil with an open spark gap which is directly connected to aerial and earth. Both illustrations come from: Archie Frederick Collins, Wireless Telegraphy. Its History, Theory, and Practice (1905).

simple spark transmitter


Nikolaus Loewe


Nicolaas van Dijk

Thank you very much for the answer Nikolaus, highly appreciated

I did not know that demonstration sets were produced an sold. I thought that the wireless technology was just the activity of people in lab's like the photo you uploaded shows and many photo's in my books. This indeed may be the explication for the very elaborated work done at this device. 

I have the book Practical wireless telegraphy by Elmer and Bucher from 1917. There are loads of schematic diagrams and photo's of very many transmitters and receivers and off coarse also the emergency set from Marcony, wich is a plain aerial set. But nothing said about your information.

I hope that more people chime in and give me more detailed info, e.g. were these sets were produced

I have put the most part of my collection of radio's in the university of Malaga. They started a small radio museum there. I think it is good that more people can enjoy the sets. But we also like to set-up some experiments that people can do, among others a spark transmitter with coherer receiver. Do you have drawing or information how to make a coherer? (type of metal powder, grain size, diameter etc.) I don't like to invent the wheel again, though may be very interesting.

Kind regards and thanks again for the information.




Michael Watterson

I think I read somewhere that there were even working models sold as "toys" for children? Am I mistaken?

Nikolaus Löwe

Indeed, there were toy sets, a well known one ist this one by the German manufacturer Bing. Another one is the "Telimco", made by Hugo Gernsback´s Electro Importing Co., and sold in 1905 for only $8.50. And yes, they work!

Mind you, there was not much commercial business for wireless set manufacturers before WW I. So some companies sold sets to colleges, universities, and schools for demonstration and teaching purposes (like e. g. Telefunken, Huth, Ernecke, Klicnik, Max Kohl), and some even targeted the popular market for electric and technical toys, like Bing and Electro Importing Co.

Some electrical teaching sets allowed for the construction of very simple spark/coherer sets, like the German "Radiomann" as late as the 1960ies!

A simple coherer can be made out of practically anything, as it is only a "bad contact". An easy arrangement is to use two small blocks of carbon, ground to carry a sharp edge, and to position a steel sewing needle across the two. With a small battery and a telephone in circuit, you have a coherer receiver. If you tolerate reduced sensitivity, leave out the battery. This is pretty much what Oliver Lodge used in 1894.

A metal filings coherer of fairly high sensitivity can be made by using two plugs of steel that just fit inside a small glass tube of about 2 - 3mm internal diameter. Let the faces of the steel plugs be slightly oblique, so as to form a v-shaped space in between them, and let them be polished. One of the steel plugs may be gold-plated, or, as a more traditional method, amalgamated with mercury. Use filings of hardened steel (as Ferdinand Braun/Siemens & Halske), nickel or German silver (as  Marconi), or gold (Slaby/Arco). Don´t use too many filings, only about 20 -25. They should all be of the same size, about 0,3 - 0,5mm, regularly shaped, and not packed tightly. With a gold coherer, the only place in which cohering really takes place, is the plain face of the polished steel plug. A coherer like this will trigger at voltages as low as 0,25V, which can be tested with D.C. Use a sensitive polarized relay of high impedance (Telefunken wound their relays to 100.000 Ohms), and a single 1.5V cell with a potentiometer across it. The hardest thing might be finding a relay that reliably switches at voltages of much less than 1V; even with a 5k resistor in series (a lightly triggered coherer doesn´t go all the way to zero). You may use a galvanometer instead, and tap the coherer back by hand.

For transmssion, one of the large piezo lighters as used in oil furnaces, equipped with a simple dipole with a tiny spark gap in between, will do the trick.

Have fun experimenting,


Nicolaas van Dijk

That is all very good and interesting information Nikolaus, thanks a lot. I will make myself a coherer like you described. Must be very interesting an a lot of fun. I keep you informed

kind regards



Paul O'Brien

Dear Nikolaus,

 When I saw the picture of Marconi with his spark receiver and paper tape recorder on your posting I thought you might like to see a Marconi artifact that was given to me many years ago. According to the notation on the envelope it came in, it is a “Piece of tape printed on Morse telegraph instrument connected with a Marconi wireless telegraph receiver at Twin Light Highlands of Navesink (NY) Telegraph Station giving report of yacht race – Oct. 20, 1899.” (I cannot read the three or four words in the last sentence, although the last word may be a name- “Duchessi”?) Marconi operated his wireless station from a yacht and reported the results as they happened.

The report on the tape describes the final race (best three out of five) of the America’s Cup held in lower New York Bay, off Sandy Hook, between the New York Yacht Club’s Columbia and its challenger, Sir Thomas Lipton's Shamrock.Columbia beat Shamrock by six minutes and 34 seconds to win the cup. Marconi had been hired by The New York Herald newspaper to report on the races.

It was the first-known commercial use of wireless telegraphy.

The first few words on the tape read “Columbia leads by a length.” Because the tape is 114 years old, although it is in very good condition, I dislike handling it. I estimate the length of the tape is around four feet. The initials “EO” are written on the end of the tape – the operator?


Paul O’Brien


Michael Watterson

Perhaps this was the earliest Commercial Wireless Telegraphy?

(From IRTS news last week)


Kingstown Regatta

The Kingstown (now Dun Laoghaire) Yacht Regatta of July
1898 is famous for being the subject of the first live
broadcast of a sporting event, when Marconi transmitted
minute-by-minute reports on the races from a boat in
Dublin Bay to a land station in the harbourmaster's
office, ensuring the speedy publication of the race
results. During the regatta, more than 700 wireless
messages about the races were transmitted, and the
commercial success
of this experiment helped to promote
the use of the radio for point-to-point communication
without the need for connecting wires.

Next weekend (20th and 21st July [2013]) the 115th anniversary
of this event is being celebrated in two Dublin
locations: at the Ye Olde Hurdy-Gurdy Museum Of Vintage
Radio in Howth, where the Howth Martello Radio Group
will be in action, while members of South Dublin Radio
Club will be at the Maritime Museum in Dun Laoghaire;
operations in these two locations will use the call
signs EI115MAR and EI115KR, respectively.

Both museums are open from 11.00 am on Saturday and
Sunday 20th and 21st July, and visitors are welcome.



Nikolaus Löwe

Dear Paul,

this is a very rare and valuable artifact you have there. The name of one of the boats on which Marconi had set up his equipment was in fact "Grande Duchesse". This must be where your tape comes from. The other vessel equipped  with a Marconi set was the "Ponce".

The story back then must have been quite exciting, and is reported in parts by Gavin Weightman in his book "Signor Marconi´s Magic Box".

In 1899, there was no competition for Marconi in reporting from the yacht races. The America´s cup races in 1901, however, were the place of an unbelievable wireless battle, as is described in Thorn L. Mayes'  excellent book "Wireless communication in the United States". Besides Marconi, DeForest's "Wireless Telegraph Co. of America" and Harry Shoemaker's and Greenleaf W. Pickard's "American Wireless Tel. and Tel. Co." had also set up stations, to the effect, that the Shoemaker equipment drowned out all wireless communication between the others. Shoemaker supposedly transmitted simple messages in the way he jammed the others...





Paul O'Brien

Many thanks, Nikolaus,


Now that you have enlightened me, I can make out the words “La Grande Duchesse on the bottom line. I thought that the last letter in Duchesse was an “i”, but I now see that the dot over the “i” was actually a comma after the “20” in the line above and that the “i” is an “e”.

The first word, however, is still a mystery. I am delighted that you found it interesting.


Thank you, again,


All the best,



Unknown Worldwide: unknown Spark Transmitter
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