What is a bug? The semi-automatic Morse key explained

A bug is a semi-automatic Morse key. It has a sideways lever: push it one way and a weighted, springy arm vibrates and sends a string of evenly timed dits for as long as you hold it; push it the other way and it closes a contact for as long as you hold it, so you make each dah by hand. It has no electronics and needs no power supply. A bug is a mechanical switch with a pendulum built in, and it keys a radio the same way a straight key does.

That split, machine dits and hand-made dahs, gives a bug both its speed and its sound.

How a bug works

A bug lies flat on the desk, with its lever moving side to side. The main parts:

• The lever. At the front there is a flat paddle for the thumb on one side and a knob for the finger on the other. On a right-handed bug, the thumb pushes to the right for dits and the index finger pushes to the left for dahs. Left-handed bugs are built as mirror images.
• The vibrating arm. A flat spring running along the key with a weight clamped to it. Push the lever toward the dit side and the arm is set swinging, like a pendulum on its side.
• The dit contact. A light spring contact on the arm that touches a fixed contact once on every swing. Each touch is one dit. Hold the lever over and the dits keep coming; let go and they stop.
• The damper. A pad that stops the arm quickly once the lever returns to the middle, so that no stray dit slips out after you let go.
• The dah contact. A plain contact on the other side, like the contacts of a straight key. It stays closed as long as your finger holds it, so a dah is exactly as long as you make it.

Behind all of this there are only two wires, just as with a straight key. To a radio or a practice oscillator, a bug is simply a switch that someone is closing very fast.

Setting the speed with the weight

The speed of the dits is set by where the weight sits on the arm. Slide it out toward the free end and the arm swings more slowly, so the dits get slower. Slide it in toward the pivot and the arm swings faster, and so do the dits.

That gives a bug a slowest speed. Even with the weight right at the end, the arm only swings so slowly, and some bugs come with an extra weight to clamp on for slower sending. A bug is happiest at moderate to fast speeds. If you send slowly, it may not suit you yet.

The weight sets the dits only. Your dahs and every gap between letters and words are still yours, and they have to match the dits. A dah should last three dits; if the arm is set fast, a correct dah will feel surprisingly short.

The other adjustments

Once the speed is right, the rest of the setup is about making each dit clean and the dah side comfortable. Change one thing at a time and listen after each.

1. The dit contact. Its adjustment decides how much of each swing the contact stays closed, which sets how heavy the dits sound against the silence between them. Adjust it until a long string of dits sounds even, like a steady sequence of equal beats with equal spaces.
2. The damper. Set it so the arm stops promptly when you let go. With too little damping, an extra dit sneaks out after the last one you meant to send.
3. The dah side. Set the contact gap and the spring tension the way you would on a straight key: enough travel to feel, enough spring to return the lever cleanly, and no more.

For more on how dit length against space changes the sound, see Dit to dah ratio and weighting in Morse code.

Sending well on a bug

A bug makes perfect dits, but only if you ask for the right number of them. Most bug errors come from that, and from the handover between your thumb and your finger.

Count runs of dits correctly. The arm keeps going as long as you hold the lever, so you have to let go at the right moment. Let go a fraction late and S ... becomes H ...., and H becomes 5 ...... Let go early and you lose one. Practice the letters and figures with runs of dits: S, H, 5, B -... and 6 -...., until the count is automatic.

Make dahs that match. Because the dits are machine-even, any wobble in your dahs stands out. Practice strings of T and M at the speed your arm is set to, and listen to whether each dah is three dits long.

Keep the handover tight. Letters that change sides, such as A .-, R .-., L .-.. and F ..-., need the move from thumb to finger, or back, to take exactly one unit of silence. A slow handover splits the letter.

Record yourself. Listen back a day later. A bug fist has a recognizable lilt, crisp dits with dahs shaped by hand, and a little of that is part of the charm. Overdone, with the dahs stretched long and lazy, it is harder to copy than it is fun to send; operators have a slang name for that style, the banana boat swing. Your fist in Morse code: what it is and how to improve it covers what other operators hear in your sending.

Where the bug came from

Semi-automatic keys spread among professional telegraphers early in the twentieth century, on landlines and on radio. The appeal was speed and comfort. A straight key works the wrist and arm on every single element, and the strain of long shifts of fast sending was often called glass arm by old telegraphers. A bug took the dits, the most repetitive part of the work, off the hand.

Where the name came from is not settled, and the stories told about it vary. What is clear is that the bug stayed in use for a long time. Electronic keyers, which time the dahs as well as the dits, later took over for most operators who send fast, but bugs are still made, still used on the air and still collected.

Should you learn on a bug?

Not as your first key. A bug rewards a hand that already has good rhythm, and it magnifies the errors of one that does not: a hesitant handover or a short dah is obvious next to a row of perfect dits. Learn the code by ear first, send steadily on a straight key or paddles, and come to a bug when you want a new challenge. Straight key vs paddles: which should you start with? covers that first choice.

Dot & Dash offers a straight key and paddles, not a bug, but the part of bug sending that is yours, the dahs and the spacing, is straight-key work. In a lesson, after each letter you key, Dot & Dash draws each dit and dah against the length it should have been and marks the ones that ran short or long, which is a useful check on your dahs before you take them to a bug.

Questions

Is a bug the same as an electronic keyer?

No. A bug is purely mechanical: a vibrating arm makes the dits and your hand makes the dahs. An electronic keyer times both the dits and the dahs for you, and it needs power.

How do you slow down a bug?

Slide the weight on the vibrating arm out toward its free end. If it is already at the end and the dits are still too fast, clamp on an extra weight if your bug came with one, or accept that very slow speeds are not what a bug does best.

Why do my S and H come out wrong on a bug?

Because the arm keeps making dits until you let go. Releasing a moment late adds a dit, turning S into H, and releasing early drops one. Practice runs of dits until the count becomes automatic.

Can a bug connect to a modern radio?

Yes. A bug is a switch with two wires, so it plugs into a straight key input like any straight key. If the radio has a built-in keyer, check its manual for how to use the key input with a straight key.