Bird - The RF Experts
8251 Series

1000 Watt, Oil-Cooled RF Termination

8251 Series, RF Loads are portable, self-contained general purpose 50 ohm coaxial transmission line RF terminations requiring no outside power source or additional equipment. The loads are Oil-assisted convection cooling for safe, continuous operation up to 1000W full rated power. They provide accurate, dependable, and practically non-reflective termination for testing and adjusting transmitters under non-radiating conditions. The load consists essentially of a cylindrical film type resistor immersed in a dielectric coolant. The resistor, individually selected for its accuracy, is enclosed in a special tapered housing which provides a linear reduction in surge impedance directly proportional to the distance along the resistor.

This series includes Models 8251D and 8251D7-16 for Digital Broadcast
(VSWR = 1.065 max., 470-860 MHz)

Model Selection
Model    Connector
8251 LC connector installed and an additional QC-N connector for lower-power testing
8251N QC-N connector for lower-power testing.
8251D 1 5/8 in EIA, Flanged
8251D7-16 7/16 Jack, IEC
product specifications:
Item No
8251 Series
Item Name
1 kW, Oil-Cooled Terminations
Power Rating
1000 W continuous
Frequency Range and VSWR
DC - 1 GHz @ 1.1 max.
1 GHz - 2 GHz @ 1.25 max.
2 GHz to 2.4 @ 1.3 max.
1.065 max., 470-860 MHz for "D" Models
Temperture Range
-40 to +45 °C
1.1 gal. (4.1 liters) Silicon Oil
Product Type
Operating Position
Horizontal Only
See Model Matrix
Gray Powder Coat
18 in x 6 in x 8.5 in (455 mm x 151 mm x 216 mm)
25 lb, 8 oz (11.5 kg)