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Why is high VSWR bad?
Driving full power into the load can propose an unsafe test setup as typically a high VSWR is a sign of damage or an error in the test setup. As power levels increase above 100 watts to 1kW and further it is increasingly difficult to build an amplifier to handle infinite VSWR or 100% reflected power.
How do I lower VSWR?
One technique to reduce the reflected signal from the input or output of any device is to place an attenuator before or after the device. The attenuator reduces the reflected signal two times the value of the attenuation, while the transmitted signal receives the nominal attenuation value.
Why does my transmitter back off when the SWR is high?
Transmitters sort of force you to do this by backing off the power when the SWR is high, meaning the load is not 50 ohms. Bypassing the “SWR foldback” and tuning for maximum output power is likely to cause efficiency and distortion to suffer more often than not.
Can a cable mismatch damage an audio amplifier?
In the audio realm, where cable lengths are insignificant compared to the signal wavelength, I would understand an impedance mismatch damaging an amplifier as follows: Take an audio amplifier that can deliver 100 watts of power into an 8 ohm speaker driver.
Can a VSWR cause a range of impedances?
Take the load at the end of the transmission line, transform it according to the electrical length of the feedline, and put that equivalent impedance right at the transmitter’s terminals and you will have the same damage. A particular VSWR can result in a range of impedances.
What causes the transistor in an amplifier to break?
Ultimately, it is impedance mismatch (really, too low an impedance) that damages transmitters. The thing to realize is the impedance seen by the final power transistors in the amplifier (the part that usually breaks) isn’t the same impedance at the amplifier’s terminals.