Question T4A05
From subelement T4 - T4A
Where should an RF power meter be installed?
Why is this correct?
An RF power meter must be installed in the feed line between the transmitter and antenna (A) because it needs to measure the actual RF power flowing to the antenna system. Installing it at the power supply output (B) or in the power supply cable (D) would only measure DC power consumption, not RF output. Option C is nonsensical as the push-to-talk line carries control signals, not RF power.
Memory tip
Remember the signal path: power supply → transmitter → feed line → antenna. RF power meters measure what's actually being radiated, so they must intercept the RF signal itself. DC measurements tell you about power consumption, but RF measurements tell you about transmission effectiveness.
Learn more
RF power meters serve dual purposes in amateur practice: measuring forward power (what you're transmitting) and reflected power (what's bouncing back due to impedance mismatch). This placement allows calculation of SWR and helps protect your transmitter from damage. Modern transceivers often include built-in SWR protection that reduces output power when excessive reflected power is detected, but external meters provide more precise measurements for antenna system optimization.
Think about it
Why do you think measuring RF power at the antenna feed point gives you more useful information about your station's actual radiated performance than measuring DC power at the power supply?