Has the same tube sockets as the 539C - No need for a CA-5 adapter to test compactrons.
Calibrated & Clean
 
Exceptional Condition Inside & Out
More details and pictures can be found here: https://www.ebay.com/itm/275088158289
 
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International Sales? Please contact for pricing.
 
Replaced the lights that illuminate the tube chart and the meter with a LED bulbs.
The original Hickok meter was cleaned and is a perfect 280uA and 645 ohms and has very smooth movement.

All the sockets are all tight under the socket savers and will remain that way with the use of the replaceable socket savers. The Hickok socket savers were removed and tested and reinstalled and are bolted down tight

Replaced the AC power cord.
 
Voltage SPECs:
The plate voltage is 150.5 SPEC is 150 +- 5 volts.
The low plate voltage is 67.0 SPEC is 68 +- 3 volts.
The Screen voltage is 133.7 SPEC is 130 +- 5 volts.
The Low Screen voltage is 57.9 SPEC is 56 +- 3 volts.
The bias voltage at 100 on the dial is 40.1 SPEC is 39 +- 1
The bias voltage at 22 on the dial is 3.0 SPEC is 3.0 +- .2

The AC signal voltages for each of the seven settings tested on
SH at 2.55 SPEC is 2.40 to 2.55
x1 at 1.29 SPEC is 1.28 to 1.30
x2 at 2.55 SPEC is 2.40 to 2.55
x4 at 1.28 SPEC is 1.23 to 1.30
x10 at .518 SPEC is .48 to .52
x20 at .251 SPEC is .240 to .255

Bias cut-off voltage tested at 35.9 and SPEC calls for over 30. The bias cut-off is used for the dual tests.

AC Plate voltages tested:
S1 at 19.5 SPEC is 18 to 20 volts.
S3 tested at 35.3 and SPEC is 35 to 38 volts.
S6/Gas tested at 174.1 SPEC is 165 to 175 volts.
S2 tested at 294.7 SPEC is 285 to 300 volts.

Checked the leakage circuit (shorts) with 500,000 ohm resistor and read at 450 on the meter. Spec call for the meter the meter to be between 375 to 475.

Checked the voltage regulator circuit, VR on the multiplier, with 150 volts on the external multi-meter and read the same on the 752A meter.

Checked the S9/ VR MILLS with results of 50 MA on the 752A meter and exactly the same external multi-meter meter.

All the filament voltages were checked and within SPEC per the min/max filament chart included in the calibration instructions.
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