Do the easy checks first
When a call is scratchy, confirm that both radios are on the same channel and that any CTCSS/DCS setting matches. Check the volume, battery level and push-to-talk button. If one handset has scan switched on, stop the scan and set it to the channel you are using. These small mismatches are easy to miss when you are in a hurry.
Give the signal a clearer path
Take a few steps outside, move away from a large metal object, or try a window or another floor. If you are outdoors, a position with fewer walls or a clearer view of the other person may help. Keep the radio upright. Hold it by the body, not over the antenna, and speak in a normal voice after a short beat when you press PTT.
Try moving both ends of the link. If you stay inside behind thick walls while the other person walks around outside, a small change at either end may help. Ask them to pause between calls so you can hear whether the change made a difference.
If the channel is busy
Listen for a moment before calling. If someone else is using the channel, wait until they finish or agree a different channel with your group. Keep the same tone setting at both ends. A tone can filter which calls open your speaker; it will not make your signal stronger or hide your call from other listeners.
Make a useful test
Try the same short call from two or three safe places and note what works. A simple note such as “good by the front window, weak in the back room” is more useful than repeatedly turning knobs at random. For a planned walk or event, test the actual route beforehand.
PMR446 radios are designed for handheld use, so adding power or an external antenna is not an ordinary signal fix. For more on realistic distances, see how far PMR446 radios reach.
A simple troubleshooting order
When one end says “I can hear you but you cannot hear me”, check that both people are taking turns and releasing the PTT button after speaking. Then check the channel and any tone code. If the audio breaks up in the same place every time, move to a clearer position or change the route rather than repeatedly changing the radio menus. If only one handset has trouble in several places, charge it fully and compare it with the other radio using the same settings.
Write down what you tried. “Worked by the upstairs window on the second attempt” is more helpful than a vague memory that it was better somewhere. If the radios are new, test the pair soon after buying them, while you can still check that both handsets, batteries and chargers work as expected.