From the manual
While receiving, serves as an S-meter to measure and display the received signal strength. While transmitting, serves as a power meter plus an ALC meter, an SWR meter, or a Speech Processor compression meter. The Peak Hold function holds each reading for approximately half a second.
RF (RADIO FREQUENCY) GAIN
The RF gain is normally configured to the maximum level regardless of the operating modes. The transceiver has been configured to the maximum level at the factory. However, you may decrease the RF gain slightly when you have trouble hearing the desired signal because of excessive atmospheric noise or interference from other stations. First, take note of the peak S-meter reading of the desired
Turn the MULTI control counterclockwise until the S-meter reads the peak value that you noted.
• Signals that are weaker than this level will be attenuated and reception of the station will become easier. Depending on the type and gain of your antenna, and the condition of the band, adjust the RF gain. When using FM mode, always adjust the RF gain to the maximum level.