J. Casale - W2NI

The M.P. Pedersen/Amplidan Key

A popular maritime key with 19th century roots

Oller Patent Drawing

Öller Key Drawing from the Anton Henric Öller Patent # 54 - 1857
Riksarkivet - the National Archives and Regional State Archives of Sweden .

One of the most sought after straight keys for use on the ham bands today is the Amplidan Key of Denmark. It is considered by both hams and retired marine radio operators as being one of the finest keys they have used. Although the key is known today as the Amplidan key, it was originally called the M.P. Pedersen key. Many were used in the maritime service and found both on ships and at shore stations.

Amplidan Key

The long-lever, rear contact features of the Amplidan key has its roots from a Swedish design dating from the 19th century. In the early 1850s, Anton Henric Öller, a silk manufacturer and Anton Ludwig Fahnehdelm, a captain in the naval mechanics corps, were involved with early experiments in Sweden with the electric telegraph. In 1853, they took part in the first telegraph trials on a line constructed between Stockholm and Uppsala, a distance of approximately 40 miles. In 1854, the Electric Telegraph Administration in Sweden appointed Öller to head their new telegraph office in Uppsala. Three years later, on November 17, 1857, Öller and a watchmaker, N.P. Lundström registered telegraph key designs in their patent application that evolved into what became known as the "Öller key."

Soon after their patent was issued, (Swedish patent #54) Öller started his own telegraph manufacturing firm in Stockholm as, Öller & Company. In the following years, three of Öller's former employees went into business for themselves and continued to manufacture the "Öller key" for many years.

Öller keys can be found today marked, Öller Co., (A.J.) Lindholm and (J.L.) Wikström or by markings of the well-known L.M. (Lars Magnus) Ericsson Company. Öller's original rear-contact, long-lever key design influenced manufacturers of commercial, amateur and military keys in that region of the world for several decades. It was one of the most significant key designs developed outside of the U.S.

Öller Key

Öller Key

Öller & Company , Stockholm Markings

Öller & Company, Stockholm Markings

One key maker in that region influenced by the design was Martin Peter Pedersen (1887-1979) of Copenhagen, Denmark. Pedersen was an electrical engineer and in 1914, Pedersen and fellow Danish engineer, Otto Skovmand formed the company, Skovmand and Pedersen. In 1919, the company was renamed to M.P.Pedersen after Skovmand's death. Pedersen manufactured radio equipment for several decades later specializing in commercial marine radio equipment. According to the Amplidan Company, it was most likely Pedersen himself who invented the M.P. Pedersen key.

The company called Amplidan was founded in 1946 by two Danish engineers: Steen H. Hasselbalch and Jens Aagaard. The name "Amplidan" is said to be derived from the combination of the words amplifier and Danmark (Denmark in Danish) as in, Ampli+Dan. In 1962, the business was taken over by a holding company, V. Kann Rasmussen. In the 1970s, the Amplidan Company purchased the rights to the M.P. Pedersen key along the rest of the Pedersen company product line. In 1986, Amplidan became a subsidiary company of Søren T. Lyngsø, making them affiliated with the Lyngsø Marine Company. Amplidan became an independent division within the Lyngsø Marine Group in 1997. Today, (2012) Amplidan products are used world-wide and the company is recognized as a supplier of communication equipment primarily for the commercial and military maritime markets.

MP Petersen Logo

MP Pedersen Logo

Side by side the M.P. Pedersen and Amplidan keys look very similar. A common difference is the Pedersen key has their company logo (MP) engraved on the top of the cover whereas the Amplidan Key has a decal on the bottom. Both keys were designed for radio telegraph service. There is only a single pair of contacts. The Öller key was designed for single current land line telegraph service typically found in that region during the 19th century. The Öller key uses two sets of contacts connected to three terminal posts. The upper and lower contacts on the lever's tongue moved between an upper and lower contact.

The Pedersen and Amplidan keys have a unique fixed torsion spring (Ref.# 36 in drawing below) that seems to add to the key"s smooth feel and stability. It also serves as the electrical conductor for the lever's contact. One of the key's large thumb screws adjusts an extension spring to vary the tension on the lever. There is a fixed lower post for a lever's resting stop. The other thumb screw is the gap adjustment and varies the distance between the contact on the steel tongue of the lever to the upper contact. This thumb screw is spring loaded with an insulated tip that pushes the fixed upper contact to the desired distance from the contact on the lever. The lever's trunnion shaft is supported by adjustable sleeve bearings. The key has a weighted base with the dimensions of 8 7/8" X 2 3/8" and an overall height of 2 1/4". The length of the lever from the tip of the tongue is 6 7/8". This is the same length as the lever on the original Öller Key.

Drawing5.jpg - 65172 Bytes

Amplidan Key Drawing

Amplidan Company

The "Amplidan Key" was manufactured in cities of Herlev and Hoersholm in the Copenhagen, Denmark area right into the 1990s. The Amplidan Company estimates that "perhaps as many as a few thousand" were built. The decal on mine has three sets of markings: Type 050713, (the model #) NR MA.JTB ("Made by JTB." JTB are the initials of a Mr. John Baggers, an Amplidan employee who made the key.) and W 9422: (Indicates it was manufactured in the year 1994, week 22.)

Amplidan Key Marrkings from 1994

Amplidan Key Markings from 1994

Back in 2006, after hearing about the Amplidan Key's reputation, I contacted the Amplidan Company inquiring if any keys were still available. At that time they were in the process of selling all their remaining stock to Marshall Emm, N1FN of Milestone Technologies in the U.S. Marshall sells Morse instruments through his company called Morse Express. Fortunately, the timing was right and I was able to get mine through Morse Express.

I recently heard from Marshall that the remaining stock he purchased at that time consisted of around 50 keys and they were all sold within 2 years. The Amplidan Key's reputation continued to grow and as word spread that NOS Amplidan keys were possibly still available, many more could have been sold since, even at its $349.95 price tag.
Marshall attempted to convince Amplidan to build another batch of 200 keys, but the best they could offer was to send just the parts for 100 keys representing a cost of $700 per key. (unassembled)

Today, finding either a M.P. Pedersen or Amplidan key is becoming difficult. Even in a depressed key market, Ebay prices for the keys run between $500 and $700. In talking with the Amplidan Company, they have no plans to start up production again but still have a supply of certain repair parts for the key.

(June 2012)

Allan Steen, & Christian, Madsen, Skytte, Amplidan Company A/S.
Amplidan / Lyngsø Marine, Lyngsø Allé 2, DK - 2970 Hørsholm.
M.P. Pedersen/Amplidan Key Drawing, Amplidan Company.
Örjan Romefors, Riksarkivet, National Archives and Regional State Archives of Sweden.
Telegraphy, T.E. Herbert, Sir Isaac Pitman & Sons, Ltd., 1939
M.P. Pedersen Logo, Jan Sköldin, SM5LNE.
Marshall Emm, N1FN, Morse Express, http://www.mtechnologies.com/
Henric Öller Launches Pioneering Enterprise, History of Ericsson, http://www.ericssonhistory.com
M.P. Pedersen, Radio Museum, http://www.radiomuseum.org/

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A version of this article was originally
published in the July,2012 issue of
"The AWA Journal" the quarterly journal of
The Antique Wireless Association.
( A nonprofit historical society )

Copyright (c) by John Casale - W2NI
Troy, New York