Bird Technologies 8650B Series - Manual (Page 13)

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Chapter 1 Introduction
The Bird 8655B/56B Moduload Coaxial Load is a self-cooling, low reflection,
non-radiating termination for high power RF transmission lines. The Load is for
use on CW, AM, FM, SSB, and TV modulation envelopes. The load may also be
used within certain limits on radar or pulse modes. Information for use involv-
ing pulse type signals should be obtained directly from Bird Electronic Corpora-
tion. The Loads are capable of continuous power dissipation of 50 kW with a
maximum voltage standing wave ratio (VSWR) of 1.10 from 1000 Hz to 900
MHz. These models provide direct connection to 3-1/8 inch 50 ohm coaxial lines.
The equipment consists of three basic systems:
z RF Load Assembly
Contains the resistor element with its internal water cooling system.
z Control System
Includes the electrical circuitry required to prevent damage to the transmitter
in case of malfunction of the load, and to protect the RF load should the water
flow slow down.
z Heat Exchanger System
The heat exchanger components consist essentially of the pump/motor, collec-
tor tank, four cover fans and four finned water cooling heat exchangers
arranged in a mated pair sets.
When used in conjunction with the appropriate Bird Model Thruline Wattme-
ter, such as those used in the 4600 and 4800 series, the 8655B/56B Moduload
Load Resistor may be used for direct RF power measurements within the
equipment ratings.
Power and Utility Requirements
The 8655B/56B loads are offered in three standard forms which differ in the
AC input power requirements.
z -115-6 for 115 V, 60 Hz
z -230-5 for 230 V, 50 Hz
z -230-6 for 230 V, 60 Hz
Items Supplied
The 8655B and 8656B loads are equipped with standard connectors. The
Model 8655B has a 3-1/8 inch EIA flanged connector. The Model 8656B has a
3-1/8 inch unflanged connector.
Items Required
z A mating connector on the coaxial transmission line.
z A conveniently located AC power receptacle to plug in the power cable.
z Distilled water for coolant.