Manual

Maintenance
15
Coolant Coolant lifetime will vary greatly depending on the operating
temperature. For heavy use (full RF power for long times, high
ambient temperature, 50 Hz ac supply), check the coolant every 500
hours. If the load has only had light duty (fraction of full power, low
ambient temperature, 60 Hz ac supply), then coolant inspection may
only be necessary every 2,000 hours.
+ NOTE: Correct any coolant leakage before inspection. (See
“Troubleshooting” on page 11)
To inspect the coolant:
y Remove the load resistor (Refer to “Load Resistor” on page 18).
y 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 6.7 gal (25.4 L) of coolant.
y With the load still on end, the coolant level should be 4
3
⁄
4
to 5
inches (125 mm) below the top of the resistor assembly mounting
ring, at ambient temperature. 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.