lf-contained. It shall be designed for operation outdoors over a temperature range of -20 to +45 degrees C (at 100% humidity). Weather resistant panels shall cover all connections. The unit shall be rated for continuous on-air operation at the transmitter's full rated output power plus 20%. The high voltage supply shall include the capability to adjust the output voltage to the requirements of various tube types and incorp- orate a step-start device to protect components from large inrush currents. The high voltage supply shall be capable of operating from the commercial power service at each site. A step-up transformer shall be provided and installed if necessary. The AC line control cabinet shall control AC power to the beam supply. To protect the IOT amplifier during an overload condition, the AC input to the beam supplies shall be removed in less than 10 milliseconds by high-speed vacuum contactors. The line control cab- inet shall include circuit breakers for protection against over-current and short circuits. Mechanical interlocks for both the line-control cabinet and the beam supply shall be incorporated for personnel safety. PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS Transmitter Control Overall transmitter system control, monitoring, and diagnostic func- tions shall be accomplished using an intuitive, high resolution, indus- trial grade, color Graphical User Interface located in the system control cabinet. GUI screen selection and commands shall be con- trolled via a touch screen interface. It is desired that basic control functions also be available using hard-wired control buttons located on the control cabinet front panel. These basic functions should include as a minimum; beam voltage on/off, filament on / off, black heat, power raise/lower, and remote/local control. The following parameters shall be monitored and available for dis- play on the transmitter control/monitoring system: Transmitter output power Transmitter reflected power IPA drive power Reject load power System int