In order for successful communication between two MF/HF radios, the transmitter and receiver on each item of equipment has to be tuned to the correct frequency. Ship to ship frequencies (simplex channels) are not numbered. This is why they have to be entered manually digit by digit.
On MF/HF radios simplex frequencies are usually entered by numeric keypad.

Practise on a MF/HF radio simulator

Press RX to enter a new Rx frequency. Enter the new frequency via the keyboard. Complete by pressing Enter. Pressing the ENTER softkey is equivalent to pressing OK
Press TX to enter a new Tx frequency. Enter the new frequency and complete by pressing Enter. Pressing the Rx softkey copies Rx frequency to the Tx.
Pressing the Tx softkey copies Tx frequency to the Rx.
Pressing the softkey deletes last entry.
Pressing the CANCEL softkey resets the display.



Setting the Rx and Tx frequency to the same value of 2182.0 kHz