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 a contact underneath. When the bar is depressed against spring tension, it forms a circuit and allows electricity to flow.The straight Morse key is still in widespread use by many Morse enthusiasts including ham radio operators. The basic key consists of a lever with a bearing of some form in the centre. A handle on one end is moved up and down to make and break a contact and thereby provide the keyed signal.