(3) The magnetron will oscillate at several different frequencies.
(4) The magnetron will have very little output power.
b. Naturally, any of these things will reduce the efficiency of the
radar set and may even take it out of operation. That's why you must take
great care when handling a magnetron and its magnet. We will discuss the
care and handling of magnetrons after this summary of magnetron operation.
22. Summary of magnetron operation.
a. Magnetron anodes are grounded to prevent a high-voltage hazard.
b. Electrons flow in the magnetron when the heated cathode is made
highly negative with respect to the anode.
c. Electrons emitted from the cathode travel in an arc because of the
powerful magnetic field at right angles to them.
d. The electrons excite the resonant cavities of the magnetron and set
up RF fields that oscillate at the cavity resonant frequency.
e. The electrons keep adding energy to the cavity RF fields, and
oscillations continue until the negative voltage is removed from the
cathode.
f. Values of cathode voltage and magnetic
field
strength
must
be
correct for the magnetron to operate properly.
g. Remember that it is the field of the permanent magnet that keeps the
electrons from rushing directly to the plate.
If there is no field or a
very weak field, the plate will be bombarded and the tube may be destroyed
at once. Even if the field is only slightly weak, it may not destroy the
tube, but it will probably cause erratic operation and reduce the life of
the magnetron.
23. Care and handling of magnetron magnets.
Although a magnetron is very rugged electrically, it should be
handled with a great deal of care. The same holds true for its magnet. The
magnet is not a toy, so resist the temptation to play with it. Keep in mind
the following precautions when handling magnetron magnets.
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