Only the Ameritron AL-811H gives you four fully neutralized 811A transmitting tubes. You get absolute stability and superb performance on higher bands that cant be matched by un-neutralized tubes. Ameritron mounts the 811A tubes vertically -- not horizontally -- to prevent hot tube elements from sagging and shorting out. Others, using potentially damaging horizontal mounting, require hard-to-find 811A tubes to retard harmful sagging and shorting. Powerful 20 CFM computer grade fan -- not an open frame phonograph motor -- draws in cool air to pressurize the cabinet and efficiently cool your 811A tubes for an extra long life. You also get efficient full-size heavy duty tank coils, computer grade capacitors, heavy duty high silicon core power transformer, slug tuned input coils, operate/standby switch, transmit LED, ALC, dual meters, QSK compatibility with QSK-5 option and much more. Specifications Output Power: 800 Watts PEP, 600 Watts CW. All Band Operation: Covers 160 - 15 Meters including WARC bands. Can be user modified for 12 and 10 meters. Four 811 Tubes: Uses four rugged, full neutralized low cost 811A PA tubes. Vertical Tube Mounting: Prevents shorting of tube filament/grid, prolongs tube life. Fully Neutralized: Improves stability and performance on higher bands. Input Tune Circuit: Adjustable rear panel slug tuned input circuit. ALC Control: Built-in adjustable ALC control. Vernier Reduction Drives: Tuning and loading reduction drives make tuning smooth and easy. Dual Illuminated Meters: Monitor vital operating functions. Heavy Duty Power Supply: 17 pounds, high silicone steel core transformer and computer grade filter capacitor gives 1700 volts high voltage at no load and 1500 Volts at full load. Multi-Voltage Operation: User selectable for 100/110/120/210/220/230 VAC operation. Shipped with transformer installed and wired for 120 VAC for domestic model or 240 VAC for export model. Air-Cooled: Quiet pressurized ventilation keeps tubes safely cooled.