Bird Technologies BA-310 Series - Manual (Page 13)

3
Chapter 2 Theory of Operation
Loads convert RF energy into heat. This heat must be quickly
transferred to the surrounding environment to prevent damage to the
load. The coolant fluid surrounding the resistor transports the heat to
the radiator walls by convection. There, air passing over the radiator
fins carries the heat away.
When a load or attenuator is mounted on the Bird Blower Assembly,
baffles cover the radiator fins so that the high airflow generated by
two blower fans is confined to passing over the fins. Up to twice as
much RF energy can be dissipated by this forced draft air flow as
compared to normal convection air currents. Thus, a 2.5 kW load will
safely dissipate 5 kW using the Bird BA–300/310.
Power Rating
Reduction
The baffles interfere with the free flow of normal air currents, causing
a 50% reduction in heat transfer efficiency if the forced airflow is
stopped. Thus, a 2.5 kW load will have its maximum power
dissipation reduced to 1.25 kW.