Nautel NX5 AM Preinstallation Manual

NX5 PRE-INSTALLATION MANUAL COOLING REQUIREMENTSVERSION 0.1 2015-08-01 PAGE 1.4.3CoolingDo not allow the transmitter room ambient air temperature to exceed 50°C (122°F) at sea level. Coolertemperatures are recommended in order to improve the reliability of the transmitter. At higher altitudes,derate the maximum inlet air temperature as follows: De-rate the ambient temperature 3ºC (5.4°F) per 500 m – or 2ºC (3.6°F) per 1,000feet – above sea level.Example: At 1600 m (1 mile) above sea level, maximum ambient temperature should notexceed 40.4ºC (104.7°F).Note: Ensure hot air from the transmitter is not drawn back into the transmitter’s cool air intake.Cooling Plant RequirementsThe NX5’s efficiency is typically 86%. Calculate the power dissipated by the transmitter using thefollowing equation:Where n is the transmitter’s efficiency and Pout is the transmitter’s average output power. Forcontinuous tone modulation, calculate the average output power of the transmitter using the followingequation:Where m is the modulation depth and Pc is the transmitter’s output carrier power.Table 1.4.1 on page 1.4.4 shows the cooling requirements for the transmitter when operating withvarious continuous tone modulation levels. To determine the number of British thermal units (Btu) beinggenerated per hour as waste heat, multiply the waste heat (in watts) by 3.413. To determine the airconditioning (in tonnes), multiply the waste heat (in watts) by 0.000285.