Bird Technologies 8141 - Manual (Page 20)

Inspection
With the rugged and simple construction of loads, periodic
inspection will be necessary at only about six month inter-
vals. Inspection should include the items listed below:
a. Cleanliness - Keep the housing and
connector free of grime.
b. Oil Leakage - Check for coolant oil
seepage from the radiator tank, and
particularly at the front and rear near
the under side of the clamping band.
See Troubleshooting Chart if leakage
is observed. Check tightness of the
clamping screw.
c. Inspect the load for completeness and
general condition of the equipment.
Preventive Maintenance
The load requires only nominal routine care. It is designed
to operate for long periods of time, if care is taken not to ex-
ceed its power handling capabilities.
The principal item of preventive maintenance is cleanliness.
Keep the cooling fins clear of accumulated dust and grime.
They interfere with the efficient and rapid transfer of heat
from the fins to the surrounding air and therefore could
cause the unit to overheat. Keep the coolant level up.
RF Assembly Test
DC Resistance
The electrical condition of the load resistor itself may be as-
certained generally from its dc resistance at room tempera-
ture.
It must be remembered that VSWR and RF impedance are
the prime requisites of a good dummy load, however, occa-
sionally checking the dc resistance will offer an indication of
a failing load.
Normally the dc resistance of the load will be a nominal 50
ohms. Stabilization of the resistive film or temperature can
cause a change in the dc resistance. Always check the load
when its temperature is between 20 and 25 degrees Celsius.
Check and record the dc resistance value of the load before
it is put into service. Use a resistance bridge or ohmmeter
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Bird Model 8141 Termaline Load Resistor