Bird Technologies 8890-320 Series - Manual (Page 27)

15
1. Turn off the RF power and interlock circuitry.
2. Disconnect the RF line.
3. Connect the multimeter test leads to the center and outer conductor of the load
resistor.
4. Compare the measured value with the previous measurement and with the baseline
resistance, measured when the load was put into service.
Note: If the new value differs from either of these by more than 1 ohm this
could indicate a failing resistor.
Figure 7 Measuring Resistance
Inspecting the Coolant Level
Coolant lifetime will vary greatly depending on the operating temperature.
•
Heavy Use (full RF power for long times, high ambient temperature, 50 Hz AC supply):
Inspect the coolant every 500 hours.
•
Light Use (fraction of full power, low ambient temperature, 60 Hz AC supply):
Inspect coolant every 2,000 hours.
Note: Correct any coolant leakage before inspection. See “Troubleshooting” on page 13.
Coolant lifetime will vary greatly depending on the operating temperature. For heavy use (full RF power for long times,
high ambient temperature), check the coolant every 500 hours. If the load has only had light duty (fraction of full power,
low temperature), then inspection may only be necessary every 2,000 hours.
n
Note: Correct any coolant leakage before inspection. (See “Troubleshooting” on page 11).
1. Remove the load resistor (Refer to “Load Resistor” on page 18).
2. Inspect the coolant.
•
The coolant should be clear, with a faint yellow tinge, and have a slightly sweet
smell. If it is black with a burnt or acrid smell, drain it and add about 2.9 gal (11
L) of coolant.
•
With the load still on end, the coolant level should be 4
3 ⁄
4
to 5 inches (125 mm)
below the top surface of the resistor assembly mounting ring, at ambient tem-
perature.
3. Add coolant if necessary.
WARNING
Disconnect the unit from all power sources before servicing. The unit may be energized from multiple sources.
The potential for electric shock exists.
CAUTION
Use only Bird coolant, P/N 5-1070, to prevent damage to the load.