A popular way of sending Morse code is to use Iambic Paddles. The paddles are a set of two switches. They’re connected to an electronic device called a “keyer”, which generates dits and dahs in the proper rhythm. When you press on one of the paddles, a series of “dits” is produced, and the other paddle produces a string of “dahs”.
When you squeeze and hold both paddles simultaneously, the keyer produces an alternating series of dits and dahs. This is why it’s called “iambic” — the alternating dits and dahs sound a bit like iambic meter in poetry, with alternating stressed and unstressed syllables.
Most iambic keyers can be switched between two modes, called “mode A” and “mode B”. What’s the difference, and why should anyone care?
The difference involves what happens when you have been squeezing the paddles, and you then release both paddles simultaneously. If the keyer is in mode A, it will finish sending the current element (dit or dah), and then stop. If the keyer is in mode B, it will finish sending the current element, then send another element, and stop.
To illustrate, consider sending the letter “C”, which is “_._.” When sending in iambic mode A, you would release the paddles during the final dit, and the keyer would stop. When sending in iambic mode B, you would release the paddles during the final dah, and the keyer would finish that dah, send a final dit, and stop.
If you follow this strategy, your brain and fingers will get used to whichever mode you use, and you’ll naturally develop the timing to release paddles at the proper time to make the letters you want to make. And then, if you change to a keyer in a different mode, things won’t be right and you’ll make mistakes.
But there’s another way. Since the difference between the two modes only concerns what happens when you release both paddles simultaneously, it follows that if you never release both paddles simultaneously, you won’t notice the difference, and you’ll learn habits that will let you switch between modes with ease.
The secret is this: When you squeeze the paddles, release each paddle as it finishes its final element. That is, for a “C”, “_._.”, release the dah paddle during the final dah, and release the dit paddle during the final dit. For a period “._._._”, release the dit paddle during the final dit, and then release the dah paddle during the final dah. This will produce the correct sound regardless of whether the keyer is in iambic mode A or B.
Of course, another way of avoiding the difference between modes A and B is to avoid squeezing the paddles at all. This is OK, but you don’t get to enjoy the zen-like pleasure of sending code using the minimal possible relaxed motion of your fingers.
For a good tutorial on how to use an iambic keyer to send Morse code, see http://morse-rss-news.sourceforge.net/keyerdoc/K7QO_Iambic_Paddle.pdf