Microwave Circuit
9-6 Magnetron High Voltage Transformer (102093) The magnetron transformer is a ferro-resonant design which limits fault currents and minimizes magnetron power changes due to input voltage changes. An automatic resetting over-temperature s witch is embedded in the high voltage secondary winding and rem oves power form the primary winding if an over- temperature condition occurs. In the C3 SERIES a separate transform er is used to preheat the filament for the magnetron for better operatio n.

+(B)
0
-
(C)
HV TRANSFORMER
OUTPUT VOLTAGE MAGNETRON VOLTAGE
Current
Flow
2400
+
-
+

-

2400
VDC
Current
Flow
+

-
-

+

2400
2400
VDC
4800
VDC
+(B)
(A)

-

(C)
- 4800 V
CAPACITOR CHARGES ON
POSITIVE VOLTAGE SWING

CHARGED CAPAC
ITOR PLUS TRANSFORMER
ON NEGATIVE VOLTAGE SWING
+2400 V
-2400 V
(A)
0

1.

The Magnetron Transformer steps up the input voltage to approximately 2 400 volts peak

(4800 volts peak to peak).

2.

The High Voltage Capacitor charges to 2400 volts on the positive going voltage via the

High Voltage Diode’s forward conduction.

3. The Magnetron Transformer plus the charged High Voltage supply up to -

4800 volts to the

Magnetron on the negative going voltage (High Voltage Diode is back biased).

4. The Magnetron converts the negative input voltage

(and Current) to RF energy at 2450

MHz with approximately 60% efficiency.

WARNING: DO NOT ATTEMPT TO MEASURE THESE VOLTAGES

FIGURE 9 - 2 Magnetron High Voltage Power Supply