Editing Telegraph key (section)

== Types ==
The first telegraph key was invented by [[Alfred Vail]], an associate of [[Samuel Morse]].<ref>{{cite book |last1=Noll |first1=A. Michael |title=Principles of Modern Communications Technology |date=2001 |publisher=Artech House via Google Books |isbn=1-58053-284-5 |page=208 |url=https://books.google.com/books?id=fZ0vDwAAQBAJ&pg=PA208&dq=telegraph+key&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwj32I-Q2ayKAxV2FVkFHTHtAz44ChDoAXoECA0QAg#v=onepage&q=telegraph%20key&f=false |access-date=16 December 2024}}</ref> Since then the technology has evolved and improved, resulting in a range of key designs.<ref>{{cite web |title=CW Mode |url=https://www.arrl.org/cw-mode |website=ARRL |publisher=The National Association for Amateur Radio |access-date=15 December 2024 |archive-date=15 December 2024 |archive-url=https://web.archive.org/web/20241215201502/https://www.arrl.org/cw-mode |url-status=live }}</ref>

===Straight keys===
A ''straight key'' is the common telegraph key as seen in various movies. It is a simple bar with a knob on top and an electrical contact underneath. When the bar is pressed down against spring tension, it makes a closed electric circuit.<ref name="elements">{{cite book |title=Elements of Telegraph Operating |publisher=International Correspondence Schools |location=Google Books |page=9 |url=https://books.google.com/books?id=luQOAAAAYAAJ&pg=PA9&dq=%22Telegraph+key%22+-wikipedia&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjf__TMy6qKAxVFqZUCHSQEKtcQ6AF6BAgJEAI#v=onepage&q=%22Telegraph%20key%22%20-wikipedia&f=false |access-date=15 December 2024}}</ref> Traditionally, American telegraph keys had flat topped knobs and narrow bars (frequently curved), while European telegraph keys had ball shaped knobs and thick bars. This appears to be purely a matter of culture and training, but the users of each are tremendously partisan.{{efn|
The longer shape of the ball-headed knobs is intended to encourage the operator to incline the hand and grasp the key more lightly, to put less strain on the arm. The design is intended to reduce [[repetitive strain injury]] once common among telegraphers, which telegraphers called "[[glass arm]]", and medical literature referred to as ''telegraphers’ paralysis''. However it is possible to injure one's arm by improperly holding the key, or striking with too much force (called "pounding brass") with either type of up-and-down key.
}}

Straight keys have been made in numerous variations for over 150&nbsp;years and in numerous countries. They are the subject of an avid community of key collectors. The straight keys also had a ''shorting bar'' that closed the electrical circuit through the station when the operator was not actively sending messages. The shorting switch for an unused key was needed in telegraph systems wired in the style of North American railroads, in which the signal power was supplied from batteries only in telegraph offices at one or both ends of a line, rather than each station having its own bank of batteries, which was often used in Europe. The shorting bar completed the electrical path to the next station and all following stations, so that their sounders could respond to signals coming down the line, allowing the operator in the next town to receive a message from the central office. Although occasionally included in later keys for reasons of tradition, the shorting bar is unnecessary for radio telegraphy, except as a convenience to produce a steady signal for tuning the transmitter.

The straight key is simple and reliable, but the rapid pumping action needed to send a string of dots (or ''dits'' as most operators call them) poses some medically significant drawbacks.
 
Transmission speeds vary from 5&nbsp;words (25&nbsp;characters) per minute, by novice operators, up to about 30&nbsp;words (150&nbsp;characters) per minute by skilled operators. In the early days of telegraphy, a number of professional telegraphers developed a [[repetitive stress injury]] known as ''[[glass arm]]'' or ''telegraphers’ paralysis''.<ref>{{cite book |last1=Cocconcelli, Marco and Fonte, Cosimo |title=Explorations in the History and Heritage of Machines and Mechanisms: Dynamic Analysis of a Semiautomatic Telegraph Key |publisher=Springer Nature |location=Google Books |isbn=978-3-030-98498-4 |page=383 |edition=7th |url=https://books.google.com/books?id=FrVoEAAAQBAJ&pg=PA382&dq=%22Telegraph+key%22+-wikipedia&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwi_zNeGzqqKAxXfMlkFHQ8TGYM4FBDoAXoECAwQAg#v=onepage&q=%22Telegraph%20key%22%20-wikipedia&f=false |access-date=15 December 2024}}</ref> "Glass arm" may be reduced or eliminated by increasing the side play of the straight key, by loosening the adjustable [[trunnion]] screws. Such problems can be avoided either by using good manual technique, or by only using side-to-side key types.<ref>{{youTube|ncOcgarGJHI|How to operate a straight key}}</ref><ref>{{youTube|nVkLr0GyJPI|Technique of hand sending (1944)}}</ref><ref>{{youTube|x6ggckXtZjs|Straight key hand sending technique approved by professionals}}</ref>

===Alternative designs===
In addition to the basic up-and-down telegraph key, telegraphers have been experimenting with alternate key designs from the beginning of telegraphy. Many are made to move side-to-side instead of up-and-down. Some of the designs, such as ''sideswipers'' (or ''bushwhackers'') and ''semi-automatic'' keys operate mechanically.

Beginning in the mid-20th century electronic devices called ''[[keyer]]s'' have been developed, which are operated by special keys of various designs generally categorized as ''single-paddle'' keys (also called ''sideswipers''), and ''double-paddle'' keys (or "iambic"{{efn|name=iamb_trochee_note}} or "squeeze" keys). The keyer may be either an independent device that attaches to the transmitter in place of a telegraph key, or circuitry incorporated in modern amateurs' radios.

====Sideswipers====
The first widely accepted alternative key was the ''sideswiper'' or ''sidewinder'', sometimes called a ''cootie key'' or ''bushwhacker''. This key uses a side-to-side action with contacts on both the left and right and the arm spring-loaded to return to center; the operator may make a ''dit'' or ''dah'' by swinging the lever in either direction. A series of ''dits'' can be sent by rocking the arm back and forth.

This first new style of key was introduced in part to increase speed of sending, but more importantly to reduce the [[repetitive strain injury]] which telegraphers called "[[glass arm]]". The side-to-side motion reduces strain, and uses different muscles than the up-and-down motion (called "pounding brass"). Nearly all advanced keys use some form of side-to-side action.

The alternating action produces a distinctive rhythm or ''swing'' which noticeably affects the operator's transmission rhythm (known as ''fist''). Although the original sideswiper is now rarely seen or used, when the left and right contacts are electrically separated a sideswiper becomes a modern single-paddle key (see below); likewise, a modern single-lever key becomes an old-style sideswiper when its two contacts are wired together.

====Semi-automatic key====
[[Image:Bug telegraph key made by Weston Hadden, c. 1913 - Bennington Museum - Bennington, VT - DSC08642.JPG|thumb|Early "bug" telegraph key invented in 1913 by Weston Hadden]]
A popular side-to-side key is the semi-automatic key or "bug", sometimes known as a [[Vibroplex]] key after an early manufacturer of mechanical, semi-automatic keys. The original bugs were fully mechanical, based on a kind of simple clockwork mechanism, and required no electronic keyer. A skilled operator can achieve sending speeds in excess of 40&nbsp;words per minute with a bug.

The benefit of the clockwork mechanism is that it reduces the motion required from the telegrapher's hand, which provides greater speed of sending, and it produces uniformly timed ''dits'' (dots, or short pulses) and maintains constant rhythm; consistent timing and rhythm are crucial for decoding the signal on the other end of the telegraph line.

The single paddle is held between the knuckle and the thumb of the right hand. When the paddle is pressed to the right (with the thumb), it kicks a horizontal [[pendulum]] which then rocks against the contact point, sending a series of short pulses (''dits'' or dots) at a speed which is controlled by the pendulum’s length. When the paddle is pressed toward the left (with the knuckle) it makes a continuous contact suitable for sending ''dahs'' (dashes); the telegrapher remains responsible for timing the ''dahs'' to proportionally match the ''dits''. The clockwork pendulum needs the extra kick that the stronger thumb press provides, which established the standard left-right paddle directions for the ''dit''-''dah'' assignments that persists on the paddles on 21st&nbsp;century electronic keys. A few semi-automatic keys were made with mirror-image mechanisms for left-handed telegraphers.