Bird Technologies 8251 Series-Manual - Manual (Page 11)

1
Chapter 1 Introduction
Bird 8251 Series Loads are portable, general purpose 50 ohm coaxial RF transmission line terminations. They are
accurate, dependable, and low reflection, dissipating up to 1000 watts of RF power. See Figure 1 on page 1 for fre-
quency ranges.
The load has a coolant chamber surrounded by radiator fins. A handle is recessed in the radiator fins. The front and
rear fins form mounting flanges which can be used as supports for freestanding use or as brackets for fixed mount-
ing. A vent plug at the top of the unit relieves internal pressure from coolant expansion. The load’s simple and rug-
ged design minimizes maintenance requirements.
Applications
Use an 8251 load:
•
As a substitute antenna for tuning transmitters under nonradiation conditions or for making routine tests
and adjustments.
•
As a substitute for any circuit loading element.
•
To measure, with a suitable meter, the power output of coaxially transmitted signals.
Items Supplied
•
Load Resistor: Pre-filled with coolant at the factory
•
Shipping Plug
•
Vent Plug
•
Instruction Manual
Figure 1 Outline Drawing
Connector Frequency Range
Thermoswitch
Temperature
8251 Female LC DC – 2400 MHz N/A *
* Optional thermoswitch kit (P/N 2450-129) available.
8251N Female N DC – 1000 MHz N/A
*
8251D †
† Requires bullet (P/N 4712-020) – not included
1-5/8” EIA Swivel 470 – 860 MHz N/A
*
8251D7-16 7/16 IEC 470 – 860 MHz N/A
*
8251T-230 ‡
‡ Bullet included
1-5/8” EIA Fixed Flanged DC – 2000 MHz 230 ºF (110 ºC)
8251T-300
‡
1-5/8” EIA Fixed Flanged DC – 2000 MHz 300 ºF (149 ºC)
WARNING
6”
(151 mm)
8.5”
(216 mm)
18” (455 mm) nominal
Connector dependent
8251T shown
15”
(380 mm)
5 / ”
(130 mm)
1
8
3.5”
(89 mm)
(4) MTG.
HOLES
VENT PLUG
INTERLOCK
THERMOSWITCH
(OPTIONAL)