Bird 8890 Series Semiconductor Termaline Coaxial Load Resistor
12
Maintenance
Cleaning Wipe the load free of dust and dirt when necessary. Excessive dust on
the cooling fins will interfere with heat dissipation. Clean the RF
connector, both metallic and insulating surfaces, with a dry, non-
residue forming solvent.
Inspection Inspect the unit every six months. Check for coolant leakage around
the clamping band and the thermoswitch. Also check for corrosion.
DC Resistance Measuring the dc resistance between the inner and outer conductors
of the RF connector shows changes in the load over time, a good check
of the load resistor’s condition. Under normal operating conditions,
the resistor should provide at least 5,000 hours of operation before
requiring any additional service. DC resistance tracking must start
before the load is put into service, and should be measured annually.
Perform the following steps and record the value for future
comparison. Make sure that you have an ohmmeter with an accuracy
of ±1% at 50 ohms and that the load temperature is between 20 and
25 °C (68 to 77 °F) before starting.
Figure 5
Measuring
Resistance
