What happens to a receiver's S-meter reading if the power output of a transmitter is increased by four times?

The correct answer is that the S-meter reading may decrease by approximately four S units due to the non-linear response of the S-meter to changes in received signal strength. The S-meter typically follows a logarithmic scale, which means that an increase in transmitter power does not produce a linear increase in the S-meter reading.

When the power output of a transmitter is increased, the signal strength at the receiver also rises, but the S-meter's response is such that it reflects changes in a logarithmic manner. Specifically, increasing the power output by four times will result in a proportional increase in signal strength, but the S-meter reflects this as a more gradual change.

For example, every increase of about 6 dB on the S-meter corresponds to a doubling of signal strength. Thus, if the signal power increases by four times (which is equivalent to a gain of 6 dB), the effect on the S-meter would likely be around 2 S units or perhaps less than that. As such, it could realistically lead to a decrease in the S-meter reading depending on how the meter is calibrated or if there are other factors at play like noise or interference.

In essence, this behavior of the S-meter to reflect changes in a non-linear manner