Hickok 539C - Continuity and Voltage Tests; Filament and Heater Continuity Test; Voltage Regulator Tube Testing

low the given striking voltage. The meter indication for a good tube is above the point
designated "RECTIFIERS OK".
18. Filament and Heater Continuity.
1. Turn the tester on.
2. Set the selectors as per chart for the tube to be tested.
3. Set the FILAMENT switch on BLST instead of voltage indicated on the chart.
4. Set the SHORT TEST switch on position 5.
5.
Place the tube in the proper socket.
If the neon lamp glows, the filament is good and a complete test should then be made
on the tube, by setting FILAMENT switch on the proper tap, and while the tube heats,
rotate the SHORT TEST SWITCH several times thru 1 to 5 positions. If no shorts are in-
dicated, set the switch in TUBE TEST position and proceed to test the tube as per chart.
If the neon lamp does not glow, the filament is open and further test is unnecessary.
Certain tubes such as the 35Z5-50Z7, etc., with tapped filaments have special continuity
test settings; see roll chart.
NOTE
It sometimes happens that a filament will show con-
tinuity when cold, but will open when it warms up.
19. Voltage
Regulator Tubes.
a. Set the selectors for V. R. tube to be tested. The test data for V. R. tubes
will be found at the top end of the roll chart. For example, the OA3.
b. Set FIL VOLTAGE switch to OFF.
c. Set selector switches to AP-0502-0.
d. Set function switch on range H, V. R. TEST.
e. Turn the bias volts toggle switch to V. R. volts and mils.
f. Turn V. R. volts knob fully counter clockwise.
g. Turn power adjust knob fully clockwise. Press P4-LOCK.
h. Place V. R. tube in proper socket and turn power ON.
i. Turn V. R. voltage control knob slowly clockwise. The large Gm meter should
start to read d. c. volts on the 0-200 volt scale.
j. Example: In the notations column for the OA3 tube appears, "Starts at about
100 Volts - Regulation = 5 volts from 5 to 40 mao ". In the column marked
MIN. MUT. CONDo is the nominal operating voltage for this tube - 75V.
k. When the V. R. tube strikes as explained in (j) above, the voltmeter reading
will drop back to operating voltage. The V. R. current is read on the 0-100
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