Telstar 1 included discrete transistors augmented by a traveling-wave-tube amplifier
to reach the required 3-W transmit power.
A solid-state high power amplifier (HPA) amplifies an offset quadrature phase-shift keying signal on the uplink, and a traveling-wave-tube amplifier
(TWTA) provides the gain for the downlink.
For decades, the baseline vacuum power component has been the traveling-wave-tube amplifier
"Now, through sheer hard work and determination, we have not only expanded capacity, but also upgraded the KPAs and added multiple Traveling-Wave-Tube Amplifiers
(TWTAs) and overhauled the power system to chart the way for future growth and expansion."
Different carriers tend to generate intermodulator products due to non-linearities in the satellite's traveling-wave-tube amplifiers
. To reduce the interfering effects of intermodulation products, the aggregate transmit power is set below full power.