Magnetron current - Place a 10 ohm 10 watt resistor in series with the HV
diode cathode and ground. Measure the voltage drop across this resistor.
Sensitivity will be 10 V/A. Normal anode current is around 300 to 400 mA
for a typical oven. This will be -3 to -4 VDC across the 10 ohm resistor
with respect to chassis ground. SET EVERYTHING UP AND THEN STAND BACK and
don't forget to DISCHARGE the HV capacitor after making the measurement: