What condition activates alternate functions on the alphanumeric keys?

The activation of alternate functions on the alphanumeric keys occurs when the device is in the F position. When the device is set to this position, it allows the user to access additional functions of the keys that are not available in the standard mode. This enables a more versatile use of the keys, facilitating a wider range of commands or inputs depending on the operational needs.

In contrast, other conditions like receiving and transmitting modes typically focus on the communication aspects of the equipment, such as sending or receiving data rather than altering key functionalities. The set position is also more about configuring the system settings rather than enhancing key utility. Thus, the F position specifically caters to unlocking alternate features associated with the alphanumeric keys, making it the correct choice.