TB 9-5915-214-24
IDENTIFICATION AND DESCRIPTION
1. Test Instrument Identification.
This bulletin provides instructions for the
calibration of Tunable Active Filter, KrohnHite, Model 3940. The manufacturer's manual
was used as the prime data source in compiling these instructions. The equipment being
calibrated will be referred to as the TI (test instrument) throughout this bulletin.
a. Model Variations. Variations, among models, are described in text.
b. Time and Technique. The time required for this calibration is approximately 4
hours, using the dc and low frequency technique.
2. Forms, Records, and Reports. Forms, records, and reports required for calibration
personnel at all levels are prescribed by TB 75025.
3. Calibration Description. TI parameters and performance specifications which
pertain to this calibration are listed in table 1.
Test instrument parameters
Performance specifications
Frequency range
20 Hz to 2 MHz
r2%, 20 Hz to 500 kHz; r5%, 500 kHz to 2 MHz
Relative Gain
Butterworth, -3 db; Bessel, -7.58 db; r2%
24 dB per octave
Insertion loss
r 0.5 dB, 0 to 2 MHz
Noise
Less than 200 PV with a detector bandwidth of 2 MHz
Greater than 80 dB
0 V, r1 mV; -15 V to +1 V, r 0.05 V
EQUIPMENT REQUIREMENTS
4. Equipment Required. Table 2 identifies the specific equipment to be used in this
calibration procedure. This equipment is issued with Secondary Transfer Calibration
Standards Set AN/GSM-286, AN/GSM-287, or AN/GSM-705. Alternate items may be used
by the calibrating activity. The items selected must be verified to perform satisfactorily
prior to use and must bear evidence of current calibration. The equipment must meet or
exceed the minimum use specifications listed in table 2. The accuracies listed in table 2
provide a four-to-one ratio between the standard and TI. Where the four-to-one ratio cannot
be met, the actual accuracy of the equipment selected is shown in parenthesis.
5. Accessories Required. The accessories required for this calibration are common
usage accessories issued as indicated in paragraph 4 above and are not listed in this
calibration procedure. The following peculiar accessories are required for this calibration:
Hewlett-Packard Model 11048C (11048C), and the TI 6 kHz high-pass and 2 MHz low-pass
filters.