This calibration procedure is for maintaining calibration of production electronic test box ATE-100 on a scheduled basis. If any of the parameters fall outside these limits, the test box can be recalibrated using trimpots accessible through the front panel. Calibration should be rechecked every 3-months.


Parameters to be checked

1.     Inject a polarity switchable DC 10V signal into RVDT Secondary Input to balance the AC Precision Rectifier

2.     RVDT Excitation amplitude range and frequency

3.     AC RMS output excitation signal at 7.02 VAC RMS

4.     AC RMS amplitude measurement error across the AC RMS voltage range

5.     Torquemotor current output and meter calibration

6.     Solenoid voltage output and meter calibration



RVDT Excitation = 3.0 kHz +/- 1% (30 Hz) = 2070 ~ 3030 Hz range.

AC Precision Rectifier Balance 10VDC on both sides +/- 0.004 VDC

AC RMS Excitation display @ 7.02VAC = +/- 0.005 VAC RMS

AC RMS Secondary display 0 to 4VAC = +/- 0.005 VAC RMS

Torquemotor current @+/- 100.0 mA & 0 mA = 0.5 mA

Solenoid Drive Voltage 28VDC +/- 0.05 VDC.


For Reference Only Tests

The 1mA for Coil Resistance test and 19.5M resistor calibrations are no longer required. These functions are for reference only and not to be used to ship product. For shipping product, use external commercial, off the shelf meters to measure coil resistance and insulation resistance.


Test Procedure

Plug in 110 VAC and turn on. All three meters and the green Insulation Resistance test LED should illuminate.


Install Test Connector Tool (TestCon) to rear DB25 pin connector as shown in Fig 1.


Connect a Banana to BNC adaptor to the RVDT Secondary input BNC jack and then a BNC to Banana adaptor into the Banana to BNC adaptor as shown in Fig 1.

Fig 1 ATE-100 TestCon tool


Connect a +10V DC Signal into the RVDT Secondary Input using a BNC test cable to a benchtop DC signal source. Most benchtop oscillators have a DC output that will work.

Set input to Secondary Input of ATE-100 TestCon tool to +10 VDC.

Record the AC Meter reading on the RVDT Module meter.


Rotate rear BNC to Banana adaptor 180 degrees to reverse polarity of the DC voltage applied to the RVDT secondary input.


Record the AC Meter reading on the RVDT Module meter.


The two reading should not differ by more than +/-0.004V DC


If the error is greater than +/-0.004VDC, perform AC Balance Adjustment in the equipment manual.


Check AC RMS Excitation Output and Meter Calibration

Connect external DMM to RVDT SEC BNC jack on ATE-100 TestCon tool.

Switch DMM to measure AC RMS

Switch ATE-100 RVDT module Coil Select to Primary

Set 10-turn dial to get 7.02 VAC RMS on DMM

Record and compare AC RMS meter reading with Datel meter on ATE-100 RVDT Module.

These should agree within 0.005VAC. If not, adjust MGain trimpot on front of ATE-100 RVDT module.


Switch DMM to measure Frequency of AC RMS signal. Should be 3.0kHz +/-30 Hz.



Set Coil Select switch to Secondary.

Either connect an RVDT to the test cables or inject a 3kHz adjustable amplitude oscillator signal into the Secondary BNC jack on the ATE-100 TestCon tool.


If using external oscillator

Disconnect test cable to fuel control or dummy RVDT.

Set oscillator for 3kHz output and compare AC RMS values of external reference meter and AC Pk meter display on RVDT Module at 0.5 VAC intervals from 0 to 7.5 volts.

Record data and plot with spreadsheet graphing routine.


If using RVDT on fuel control or in protractor:

Rotate the Power Lever angle input to RVDT and record AC RMS values of external reference meter and AC Pk meter display on RVDT Module at 0.5 VAC intervals from 0 to 7.5 volts.

Record data and plot with spreadsheet graphing routine.


Calibrate Speed Trim Torquemotor Module

Connect DMM configured to measure current mA to STrim CH1 BNC connector. Set Coil select to CHB.

Disconnect cables to fuel control or dummy resistor (A parallel path will throw off the measurement)

Turn 10-turn dial on TM Module full CCW. Record mA reading on Datel meter and external DMM. They should agree within 0.5 mA. Adjust Datel meter gain to trim.

The primary calibration of torque motor current is by resistor selection and soldering the right resistors onto the TorqueMotor driver board.  


Adjust trimpot on rear of meter through a split between two wires in the ribbon cable until meter agrees with external reference meter. Record both readings.



Turn TM SetPoint pot fully CW, measure and record two meter readings.

Disconnect DMM and read Datel meter. The meter displays the zero error.

The two meters should agree within 0.5 mA on both ends and at zero.


Flip Coil Select switch to to Coil A, move DMM to STrim CH2.

Observe meter to see that the current is the same through both coils. The coils are connected together inside the Torquemotor, so this step is actually just checking the test cables.


Disconnect DMM and reconfigure to measure VDC.

Connect DMM to VBV BNC on ATE-100 TestCon tool and connect DB25 connector to fuel control or dummy loads. We want a load on the circuit when checking its calibration.

Toggle VBV switch on solenoid module to On.

Verify that external meter and Datel meter agree within 0.05VDC.

End of ATE-100 Calibration Quick Check procedure