Harris Broadcast Flexiva FAX 5KW, Technical Manual

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Section-1 Introduction
October 28, 2013
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Copyright ©2013, Harris Broadcast WARNING: Disconnect primary power prior to servicing. 888 ‐ 2720 ‐ 001
Figure 1-13 Cooling Intake/Exhaust
Note
Consult the data sheets in this section of the manual for details of cooling requirements for each FAX
model.
In general, transmitter cooling systems fall into two categories:
An open system in which the heated transmitter exhaust passes through a dedicated duct to the outside of the
transmitter building. The transmitter may receive fresh outside air directly through a separate intake duct or may
receive ambient air from the transmitter hall, with the transmitter hall being supplied make ‐ up air from outside via a
filtered inlet vent. With an open system, it is imperative to correctly balance the input and output air flow volumes,
paying particular attention to the pressure drops in external ducts and providing external blowers to overcome these
losses and ensure correct air flow. The Flexiva transmitter internal air system is designed to supply sufficient air at
the required static pressure to cool the transmitter only and all external duct losses must be compensated for by
external blowers (this includes the optional intake plenum). Outside air containing salt or pollution must have those
items removed by an adequate filtration system, and any pressure drops caused by filtration must also be
considered.
A closed system in which the transmitter exhausts and inputs air directly to and from the transmitter room. The
transmitter room is closed to outside air and makes use of air conditioning units to remove the resulting heat
buildup. This type of system is recommended in geographic areas with especially salty, sulfuric, or otherwise
polluted air. With a closed system, it is imperative to correctly balance the heat load. That is, to size and position
the air conditioning units properly to handle the heat generated by the transmitter, ancillary equipment, building
lighting, and even solar radiation entering through windows. In may also be desirable to oversize the air
conditioning system to include the heat dissipated by the station test load, when in operation.
Figures for both the transmitter heat load and air flow volume are provided in the transmitter Outline Drawing 843 ‐
5614 ‐ 103 . Consult a professional heating and ventilation expert in your area for help in designing the building
cooling system.
When the installation is to be made at a high altitude, it will be necessary to derate the upper temperature range.
The Harris Broadcast transmitter is rated to operate from 0° to +45°C at sea level. The upper temperature range
must be derated by 2°C per 300 meters (1000 feet) above sea level.