TB 9-6685-331-50
12. Calculation of New
Mantissas
a. Performance Check
(1) Connect the 100Ω standard resistor to RTD channel 04 (probe No. 1). Allow 5
to 10 minutes for warm-up and settling time.
(2) The reading in the Data Value window is the raw a/d count of the 100Ω
resistor. After warm up, record the mean value of several readings. This reading will be
used in later calculations
(3) Repeat steps (1) and (2) using the 50Ω, 200Ω, and 300Ω resistance standards.
Record the mean of each.
(4) Steps (1) through (3) must be repeated for each channel (probe) that has to be
calibrated.
(5) Access the ARMYCAL.BAS computer program and, as prompted by the
program, enter the appropriate data to be calculated. This will include the serial
number of the TI, channel number, mean value of the a/d count for each resistor, and the
actual (test report) value of the corresponding standard resistor.
(6) Results of the program will provide new mantissa values for M and B and the
computed resistance values of the standard resistors.
(7) Review the program results to verify that the resistor values are within the
specified tolerance of +50 ppm.
(8) If the results are acceptable, continue with next section; if not acceptable, the
channel(s) in question will require factory repair.
b. Adjustment. No adjustment can be made.
13. Install New Mantissa Values for M and B
a. Performance Check
(1) Apply the configuration panel to front of the TI.
(2) Press SHIFT and ENTER keys
(3) Repeat paragraph 11, steps a(2) through a(20) to install new mantissas. BE
VERY CAREFUL to clear the temporary high and low mantissas for M and B by
pressing CE key at the appropriate prompts, and replace them with the new M and B
values obtained from the computed calibration report. Be sure to include the exponent
with the proper sign (+ or -) for each mantissa.