Editing Keyer (section)

== Radiotelegraph keyers ==
[[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. It is an example of a single-lever, semi-automatic mechanical key.]]

=== History & telegraphy background ===
In [[telegraphy]], so-called [[Telegraph key#Dual-lever paddles|''iambic'' keys]] developed out of an earlier generation of novel side-to-side, double-contact keys (called "bushwhackers") and later, mechanical semi-automatic keys (called "bugs"). Semi-automatic keys were an innovation that had an impulse driven, horizontal pendulum mechanism that (only) created a series of correctly timed [[Morse code|"dits"]]. The pendulum would repeatedly tap a switch contact for as long as its control lever was held to the right (or until the impulse from the thumb push was exhausted); telegraphers were obliged to time the [[Morse code|"dahs"]] themselves, by pressing the lever to the left with their knuckle, one press per "dah". When the lever is released, springs push it back to center, break the switch contact, and halt and reset the pendulum. Because the "dits" are created automatically by the pendulum mechanism, but the "dahs" are keyed the old-fashioned way, the keys are called "''semi''-automatic". (Modern electronic keyers create both the "dits" and the "dahs" automatically, as long as one of the switches is in contact, and are called "''fully''-automatic".)

More than just convenience, the keys were needed for medical reasons: Telegraphers would often develop a form of [[repetitive stress injury]], which at that time was called "[[glass arm]]" by telegraphers, or "telegraphers’ paralysis" in medical literature. It was common and was caused by forcefully "pounding brass" up-and-down on conventional telegraph keys. Keys built for side-to-side motion would neither cause nor aggravate the injury, and allowed disabled telegraphers to continue in their profession.

=== Modern telegraphy ===
{{unreferenced section|date = June 2008}}
[[Image:Elbug.jpg|thumb|Electronic paddle keyer (homemade in 1972) which combines both the key (paddles) and the keyer (electronics). This is an example of a fully automatic, double-lever iambic key + keyer combined.]]
With the advent of [[Solid-state electronics|solid state]] electronics, the convenience of ''fully'' automatic keying became possible by simulating and extending the operation of the old mechanical keys, and special-purpose side-to-side keys were made to operate the electronics, called ''[[iamb (poetry)|iambic]]'' telegraph keys after the rhythm of telegraphy. In  ''iambic'' telegraphy the "dot" and the "dash" are separate switches, activated either by one lever or by two separate levers. For as long as the telegrapher holds the lever(s) to the left or right, one of the two telegraph key switches is in contact; the electronics in the keyer will respond by sending a continuous stream of "dits" or "dahs". The operator sends codes by choosing the direction the lever is held, and how long it is held on each side. If the operator swings from side to side ''slightly'' erratically, within some limits the electronics will none-the-less produce perfectly timed codes.{{citation needed|date=June 2008}}

* The '''''key''''' is the double switch, operated by moving a single or double lever in a sequence of left and right presses, and on a double-lever key, also by pressing both levers together at the same time ("squeezing").
* The '''''keyer''''' is the box of electronics that the key is plugged into, which in turn plugs into the socket on the radio which an old-style "straight" key would plug into, which the keyer simulates.{{citation needed|date=June 2008}}

Modern keys with only one lever, which swings horizontally between two contacts and returns to center when released, are called "single paddle keys"; they are also called "bushwhackers" or "sideswipers", the same as the old-style double-contact single-lever telegraph keys. The double-lever keys are called "iambic keys", "double-paddle keys", or "squeeze keys". The name "squeeze key" is because both levers can be pressed at the same time, in which case the electronics then produces a string of "dit-dah-dit-dah-..." (''[[Iamb (poetry)|iamb]]ic'' rhythm, hence "iambic key"), or "dah-dit-dah-dit-..." (''[[trochaic]]'' rhythm), depending on which side makes contact first. Both types of keys have two distinct contacts, and are wired to the same type (stereo) plug, and can operate the same electronic keyer (for any commercial keyer made in the last 40&nbsp;years or so) which itself connects into the same (monophonic) jack on a radio that one of the old-fashioned type telegraph keys plug into.{{citation needed|date=June 2008}}

Fully automatic electronic keying became popular during the 1960s; at present most Morse code is sent via electronic keyers, although some enthusiasts prefer to use a traditional up-and-down "straight key". Historically appropriate old-fashioned keys are used by naval museums for public demonstrations and for re-enacting [[American Civil War|civil war]] events, as well as special radio contests arranged to promote the use of old-style telegraph keys. Because of the popularity of iambic keys, most transmitters introduced into the market within the current century have keyer electronics built-in, so an iambic key plugs directly into a modern transmitter, which also functions as the electronic keyer. (Many modern electronic keyers and nearly all radio built-in keyers electrically detect whether the inserted plug belongs to an old type, single-switch key [monophonic plug], or a new type, double-switch key [stereo plug], and respond appropriately for the key that is wired to the inserted plug.){{citation needed|date=June 2008}}