Heathkit HA-20 6-Meter Linear Amplifier Requires 2.5 to 10 watts P.E.P. driving power for a full 70-watts P.E.P. output. Tuned-grid input permits a variety of drive power levels. The tuned link-coupled output easily matches any 50 to 75 ohm coaxial transmission line. Complete RF shielding. Push-pull 6146 final amplifiers are neutralized for maximum stability. Forced-air cooled. Panel metering of final grid current, plate current, and relative power output.