Nautel NARF79, Installation Manual

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VX150 TO VX2 INSTALLATION MANUAL COOLING REQUIREMENTS
PAGE 1.4.2 VERSION 0.3 2021-01-14
Cooling
Do not allow the transmitter room ambient air temperature to exceed 50°C (122°F) at sea level. Cooler
temperatures are recommended in order to improve the reliability of the transmitter. The transmitter
contains protection circuits that monitor the intake temperature and may inhibit or reduce the RF
output power if the temperature exceeds the acceptable limit. At higher altitudes, derate the maximum
intake air temperature as follows:
 De-rate the ambient temperature 3ºC (5.4°F) per 500 m – or 2ºC (3.6°F) per 1,000 feet – above sea
level.
Example:
At 1600 m (1 mile or 5280 ft) above sea level, maximum ambient temperature should
not exceed 40.4ºC (104.7°F).
Ensure that hot, exhaust air from the transmitter is not drawn back into the transmitter’s cool air intake.
Cooling Plant Requirements
Table 1.4.1: Cooling Plant Requirements for the VX Transmitter
Calculating BTU Cooling Requirements
To determine the number of British thermal units (Btu) being generated per hour as waste heat, multiply
the waste heat (in watts), derived from the transmitter output power and its typical efficiency, by 3.413.
Heating
The transmitter room must contain a heating system that will ensure the ambient air temperature does
not drop below 0°C (32°F).
TRANSMITTER
(FM MODE)
OUTPUT
POWER
(WATTS)
TYPICAL
EFFICIENCY
(%)
WASTE
HEAT
(WATTS)
BTU/HOUR
TYPICAL AIR CONDITIONING
REQUIRED IN CLOSED ROOM
COOLING (TONNES)
VX150 165 51.3 80 273 0.023
VX300 330 64.6 117 399 0.033
VX600 660 73.7 174 594 0.049
VX1 1100 75.2 273 932 0.078
VX1.5 1650 72.5 454 1550 0.129
VX2 2200 74.9 552 1884 0.157