Bird Technologies 8630B Series - Manual (Page 17)

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Chapter 1 Introduction
This publication refers to the Moduload RF Load Resistor Series 8630
and 8630B. The differences between models are listed in the
specifications. All models will generally be referred to as a load
throughout this manual.
The information in this instruction book pertains to all models except
noted differences referred to in the text.
This chapter contains intoductory information including items
supplied, items required, unpacking, inspecting, and the
specifications.
Purpose and
Function
The Bird Moduload Loads are self-cooling, low reflection, non-
radiating terminations for high power 50 ohm RF transmission lines.
They are for use on CW, AM, FM, SSB, and TV modulation envelopes,
and within certain limits on radar or pulse modes. Information for
use involving pulse type signals should be obtained directly from Bird
Electronic Corporation.
Performance
Characteristics
and Capabilities
The 8630 and 8630B series Loads are capable of continuous power
dissipation of 10 kW with a voltage standing wave ratio (VSWR) of
less than 1.1 to 1.0 from 1 kHz to 1000 MHz. The respective models
provide direct connection to 3-1/8 inch and 1-5/8 inch 50 ohm coaxial
lines.
The equipment consists of three basic systems: the RF load assembly,
the control system, and the heat exchanger system. The load
assembly contains the resistor element with its internal water cooling
system. The 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. The
heat exchanger components consist essentially of the pump/motor, the
side blower, the coolant collector tank, and a finned cooling coil unit
opposite the blower.
When used in conjunction with the appropriate Bird Model Thruline
Wattmeter, such as those in the 4600A, 4800A or 4712 series, the
Moduload Coaxial Load may be used for direct RF power
measurements within the equipment ratings.