Iambic Keying Mode A vs B: Setting Up Your Paddle and Keyer

Sooner or later every CW operator who moves beyond a straight key meets the same menu item in a transceiver or keyer: iambic keying, with a choice between Mode A and Mode B. Many operators pick one at random, discover that their sending feels slightly wrong, and blame their fist. In reality the two modes behave differently in one specific situation, and once you understand that situation the choice becomes simple.

This guide explains what iambic keying is, the exact difference between Mode A and Mode B, how dot and dash memories fit in, and how to adjust a paddle and keyer so that your CW sounds clean at any speed. It is written for operators who already know Morse code and want their sending to be accurate and relaxed rather than a constant fight with the equipment.

What Iambic Keying Actually Is

An electronic keyer generates dots and dashes of perfect length from a paddle. You press one side for dots and the other side for dashes, and the keyer produces a continuous string of correctly spaced elements for as long as you hold the paddle closed. The keyer, not your hand, decides how long each element and each gap is.

A dual-lever paddle has two independent levers, one for dots and one for dashes. If you press both at the same time, which operators call squeezing, an iambic keyer produces alternating elements: dot-dash-dot-dash, or dash-dot-dash-dot, depending on which lever closed first. The name comes from the iamb in poetry, a short syllable followed by a long one.

Squeezing lets you form characters with fewer hand movements. The letter C, dash-dot-dash-dot, can be sent with a single squeeze that starts on the dash lever. The letter L, dot-dash-dot-dot, can be formed with a squeeze released at the right moment and a final dot. Operators who learn to squeeze well send with less motion and less fatigue, which matters during long contests and pileups.

Not everyone squeezes. Plenty of excellent operators use a dual-lever paddle as if it were a single-lever one, pressing only one side at a time. For them the difference between Mode A and Mode B hardly matters, as you will see below. The iambic keyer features only become significant when both levers are closed together.

Single-lever and dual-lever paddles

A single-lever paddle has one arm that moves left for one element and right for the other. Because you cannot close both contacts at once, it cannot produce iambic sequences, and the Mode A or Mode B setting has no effect. Some operators prefer single-lever paddles precisely because they are simpler: every element you hear is the result of a deliberate movement.

A dual-lever paddle can be used either way. You can squeeze it, or you can operate it like a single-lever paddle by never pressing both sides at once. This is why many operators buy a dual-lever paddle, learn on it without squeezing, and only explore iambic technique later.

Mode A vs Mode B: The One Difference That Matters

Both modes behave identically when you press only one lever. Hold the dot lever and both produce dots; hold the dash lever and both produce dashes. The difference appears only at the moment you release a squeeze.

• Mode A: when you release both levers, the keyer finishes the element it is currently sending and then stops. What you hear is what you were holding.
• Mode B: when you release both levers while an element is being sent, the keyer finishes the current element and then adds one more element of the opposite type. It remembers that the other lever was closed during the element and completes the alternation.

That extra element is the whole story. With Mode B, a squeeze released slightly early still produces the complete alternating pattern, so Mode B rewards operators who learned to release early. With Mode A, the keyer sends only what you hold, so Mode A rewards operators who keep the squeeze closed until the last element they want has started.

Mode B is often associated with the keyer chips designed by John Curtis, which were widely used in early electronic keyers and transceivers, and many operators learned on that behaviour. Mode A corresponds to keyer designs that do not add the trailing element. Both are valid; neither is more correct.

An example: sending the letter C

To send C with a squeeze, you start with the dash lever and close the dot lever almost immediately, producing dash-dot-dash-dot. The question is when you let go.

In Mode A you must hold the squeeze until the final dot has begun. Release too early, during the second dash, and you get dash-dot-dash, which is K. In Mode B you can release during the second dash; the keyer notices that the dot lever was closed during that dash and appends the final dot for you, so you still get C. Operators trained on Mode B therefore release earlier, and when they switch to Mode A they suddenly send K instead of C, or N instead of R.

The reverse problem is just as common. An operator trained on Mode A who switches to Mode B finds that the keyer seems to add stray elements, because their habit of holding the squeeze slightly longer now triggers the bonus element. This is the classic complaint that a new radio “sends extra dots”.

Which Mode Should You Choose?

The honest answer is: whichever matches your hand, and then stay with it. Switching back and forth is what causes errors. A few practical guidelines help.

• If you do not squeeze, the choice makes almost no difference. Mode A is slightly more forgiving if you occasionally close both levers by accident, because it never adds an element you did not hold.
• If you are just starting to learn iambic technique, many teachers recommend Mode A because it gives direct feedback: every element corresponds to a lever you were holding. Others recommend Mode B because it needs fewer precise movements once learned. Pick one and practise consistently.
• If you already squeeze fluently, keep the mode you learned on. Your release timing is a deeply ingrained habit, and retraining it is rarely worth the effort.
• If you operate several radios, set them all to the same mode and the same weighting. Inconsistent keyer settings across radios are a common source of mystery errors in multi-radio contest stations.

Some keyers also offer other modes, such as Ultimatic, where the last lever pressed takes priority instead of alternating, or a bug mode that produces automatic dots and manual dashes. These are useful for particular styles but are separate from the iambic A and B choice.

Dot and Dash Memory

Element memory is closely related to Mode B but not identical. A keyer with dot memory remembers a brief tap on the dot lever made while a dash is being sent, and sends the dot after the dash ends. Dash memory does the same for a dash tapped during a dot. Without memory, a quick tap during an element can be lost because the keyer was busy.

Memory makes fast sending easier, because your hand can be slightly ahead of the keyer. It can also cause unwanted elements if you brush a lever by accident. Many keyers allow dot and dash memory to be switched on or off separately. If you notice stray elements that you did not intend, try turning memory off before you blame the mode or the paddle.

The behaviour of Mode B can be thought of as a kind of memory that applies at the end of a squeeze. That is why switching both Mode B and element memory on, and then using a sensitive paddle with small contact spacing, can feel unpredictable to an operator who is not used to it.

Keyer Settings Compared

Most keyers, whether built into a transceiver or standalone, expose a similar set of controls. The table below summarises what each one does and a sensible way to approach it.

Weighting is worth a special note. Standard Morse timing uses fixed relationships between the length of a dot, a dash and the gaps. Heavier weighting lengthens elements relative to spaces, and lighter weighting shortens them. Some transmitters shorten or lengthen keyed elements slightly because of their keying circuits, especially with full break-in, and weighting can compensate. Changing weighting just to make your signal sound different usually makes it harder to copy, so leave it at standard unless you have a reason.

Setting Up the Paddle Itself

A keyer can only be as precise as the paddle that drives it. Paddle adjustment is personal, but a few principles apply to almost every design. Spend time on this once, write down the settings that suit you, and you will rarely need to touch them again.

Contact spacing

Contact spacing is the distance a lever travels before it closes its contact. Very wide spacing means a lot of movement for every element, which slows you down and tires your hand. Very narrow spacing makes the paddle sensitive enough that a slight tremor or a heavy touch sends unintended elements. Start with a small but clearly felt movement, then narrow it gradually as your sending improves. Faster operators generally prefer closer spacing.

Spring tension or magnetic return

Tension sets how firmly the lever returns to centre and how much force is needed to close it. Too light, and the paddle feels vague and can bounce. Too heavy, and your fingers fatigue during long sessions. Many operators set tension so that the lever returns crisply without needing to be pushed back, and so that a deliberate but light press closes the contact.

Stability and position

A paddle that slides across the desk forces you to hold it with your other hand, which ruins rhythm. Use a heavy base, a non-slip mat or a mounting plate. Position the paddle so that your forearm can rest on the desk and your wrist stays relaxed. Most CW fatigue comes from tension in the forearm and shoulder rather than from the fingers.

Wiring and polarity

Most paddles connect through a three-conductor plug: one contact for dots, one for dashes and a common return. If dots and dashes are swapped, use the keyer’s paddle reverse setting rather than rewiring. If a radio offers separate jacks for a straight key and a paddle, check that the menu is set to paddle on the jack you use, otherwise the radio may treat a paddle as a straight key and send continuous tone.

Practising Iambic Technique

Learning to squeeze is mostly a matter of timing, and timing is learned by repetition with immediate feedback. Set your keyer to a speed slightly below your comfortable sending speed, so that you have time to think about release timing. Then practise characters that benefit most from squeezing: C, K, R, L, F, Q, Y and the full stop.

Listen critically to your own sending. Record a few minutes and copy it back later, or send into a CW decoder or skimmer and see whether the decoded text matches what you intended. Decoders are not perfect judges of style, but consistent misdecodes of the same character usually point to a release timing problem. If you are still building your receiving and sending skills overall, our guide to learning Morse code and building CW speed covers practice methods that work alongside keyer technique.

Once your squeezes are reliable, raise the speed in small steps. Iambic timing scales with speed; what worked at a moderate speed will need a slightly earlier release at higher speed in Mode B, and slightly more precise holding in Mode A.

Common Problems and Their Causes

Most sending problems that operators attribute to their hand are actually configuration issues. Before you spend weeks retraining, check these.

• Extra dots or dashes at the end of characters: usually Mode B combined with a habit of holding the squeeze too long. Try Mode A, or turn element memory off.
• Characters missing their final element: usually Mode A combined with a habit of releasing early. Try Mode B.
• Random stray elements: contact spacing too close, tension too light, or a sticky contact. Clean the contacts and widen the spacing slightly.
• Characters running together: spacing between characters is a human skill, not a keyer one. Autospace can help, but practising deliberate gaps is the real fix.
• Clipped first element after receive: often a full break-in timing issue in the transmitter rather than a keyer setting. Check the radio’s break-in delay and keying settings.
• Keyer works on one radio but not another: the menus differ. Compare mode, weighting, memory and paddle reverse on every radio you use.

Iambic Keying in Contests and Pileups

In contests most exchanges are sent from computer memories, so the paddle is used mainly for corrections, fills and unusual calls. That changes the priorities. Reliability matters more than elegance, and a paddle setting that lets you send a quick repeat or a corrected callsign without errors is worth more than the fastest possible squeeze technique.

In pileups, especially when you are calling a rare station, a clean, correctly spaced callsign stands out. The DX operator often copies the strongest clear pattern, not the loudest signal. Accurate iambic keying, with consistent weighting and no stray elements, is part of that. If you are new to calling DX, our guide to working a pileup covers timing and calling technique in more detail.

When you start making contacts with a paddle, the structure of a simple exchange matters too. The walkthrough on making your first HF contact shows how a typical QSO is built, which is useful practice material for paddle sending as well.

The Bottom Line

Iambic keying lets a dual-lever paddle produce alternating dots and dashes when you squeeze both levers. Mode A and Mode B behave the same until you release a squeeze: Mode A stops after the current element, while Mode B adds one more opposite element. Choose the mode that matches how you release, set every radio you use to the same mode and weighting, adjust contact spacing and tension so the paddle feels precise but relaxed, and use element memory only if it helps rather than hinders. Most “bad fist” problems turn out to be settings, and they are much easier to fix than habits.

Frequently Asked Questions

What is iambic keying?

Iambic keying is a feature of electronic keyers used with dual-lever paddles. When both levers are pressed together, the keyer sends alternating dots and dashes, which lets operators form characters such as C or Q with fewer hand movements.

What is the difference between iambic Mode A and Mode B?

They differ only when you release a squeeze. Mode A finishes the current element and stops. Mode B finishes the current element and adds one more element of the opposite type, so an early release still completes the alternating pattern.

Is Mode A or Mode B better for beginners?

Neither is objectively better. Many teachers suggest Mode A because every element corresponds to a lever you are holding. What matters most is choosing one mode and practising with it consistently rather than switching between them.

Does iambic mode matter if I do not squeeze?

Hardly at all. If you only ever press one lever at a time, Mode A and Mode B produce identical results. The setting only affects what happens when both levers are closed together and then released.

Why does my keyer send extra dots?

The most common cause is Mode B combined with holding a squeeze slightly too long, or element memory capturing an accidental tap. Try Mode A, turn dot memory off, or widen the paddle contact spacing slightly.

How should I adjust paddle contact spacing?

Start with a small but clearly felt movement before the contact closes, then narrow it gradually as your sending improves. Too wide slows you down, while too narrow sends unintended elements from small hand movements.