Bird Technologies 8255 - Manual (Page 13)

Chapter 1
Introduction
This publication refers to the Termaline Coaxial Load Re-
sistor Models 8251, 8252, and 8255. The differences be-
tween models are listed in the specifications. All models
will generally be referred to as a load thoughout this
manual.
The information in this instruction book pertains to all
models except noted differences referred to in the text.
Purpose and
Function
The Bird Termaline Coaxial Load Resistors are portable,
general purpose 50 ohm coaxial transmission line termi-
nations. These loads provide accurate, dependable, and
practically nonreflective line terminations.
These models are rectangular in shape with transverse
fins encasing a dielectric coolant cylinder. A retractable
handle is recessed in the radiator fins. The front and rear
fins are made of heavier gauge material and are bent 90°
to form bottom mounting flanges. These flanges are sup-
ports for free standing use, or brackets for fixed mount-
ing. Holes are provided in the flanges for fixed mounting.
Applications
Use these loads:
s As a substitute antenna for tuning transmit-
ters under nonradiation conditions or making
routine test and adjustments.
s As a substitute for any circuit loading ele-
ment.
s To measure, with a suitable indication device,
the power output of any coaxially transmitted
signal within their range.
Performance
Character-
istics and
Capabilities
Models 8251 and 8252 loads can absorb up to 1000 watts
continuously and dissipate it harmlessly as heat over a
frequency range of dc to 2400 MHz. They will show a
maximum VSWR of 1.10 from dc to 1000 MHz, 1.25 from
1000 to 2000 MHz and , for Model 8251 only, 1.30 from
2000 to 2400 MHz.
1