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Microwave Leakage Measurement
The door and cavity of the Phoenix are designed for durability and reliable operation
under severe laboratory conditions. External radiation checks are performed on the
instrument at several points in the manufacturing process to ensure that microwave
leakage is only a fraction of that permitted by U.S. law (5mW/cm
2
).
The door of the Phoenix is equipped with a safety interlock system which stops the
generation of microwave energy when the instrument door is ajar. If the interlock
system fails, the fusible link to the magnetron will open, rendering the microwave
power system inoperable.
To verify that door seals and interlock system are working properly, the Phoenix
should be tested periodically for microwave leakage. Leakage measurements should
also be performed at any time that damage to the instrument door has occurred
or following replacement of any high voltage component. To test for microwave
leakage, ensure that the muffl e furnace is properly positioned within the instrument
cavity and that the thermocouple is properly connected. Program the instrument for
a quick test procedure. With the instrument operating in the pre-heat cycle, use a
federally approved microwave leakage detector such as the Holaday Model HI-1500
and measure the microwave leakage around the door seal, at the louvers in the
cover, and at the fan grills in the cover. Leakage should not exceed 5mW/cm
2
. If
the instrument shows excessive microwave leakage, do not attempt further operation.
Contact the CEM Corporation Service Department or your local distributor.
Microwave test meters are available from CEM Corporation. CEM does not recom-
mend use of inexpensive meters available in electronics stores because they lack the
necessary sensitivity to properly test an instrument for microwave leakage.
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