Question T7C05
From subelement T7 - T7C
Why do most solid-state transmitters reduce output power as SWR increases beyond a certain level?
Why is this correct?
High SWR causes reflected power to return to the transmitter, which can overheat and damage the output amplifier transistors in solid-state radios. Modern transmitters have built-in protection circuits that automatically reduce power when SWR exceeds safe levels. This prevents costly damage to sensitive semiconductor components. Options B and C are incorrect - power reduction isn't for FCC compliance or current supply issues. Option D is backwards - reducing power doesn't fix the impedance mismatch causing high SWR.
Memory tip
Look for protection-related answers in transmitter questions. When equipment automatically reduces performance (power, gain, etc.), it's usually self-preservation, not regulatory compliance. The key pattern: reflected energy always threatens the source equipment first.
Learn more
Understanding this protection mechanism helps in practical operation. When your radio reduces power output during transmission, check your antenna system first - loose connections, water in coax, or antenna damage often cause SWR spikes. The protection circuit is your early warning system that something in your RF path needs attention before permanent damage occurs to expensive amplifier components.
Think about it
Why do you think tube-type transmitters are generally more tolerant of high SWR than solid-state transmitters?