TB 9-4931-533-40
IDENTIFICATION AND DESCRIPTION
1. Test Instrument Identification.
This bulletin provides instructions for the
calibration of Attenuator and Signal Generator Calibrator, Weinschel Engineering, Model
VM-4A. 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. None.
b. Time and Technique. The time required for this calibration is approximately 4
hours, using the microwave technique.
2. Forms, Records, and Reports
a. Forms, records, and reports required for calibration personnel at all levels are
prescribed by TB 750-25.
b. Adjustments to be reported are designated (R) at the end of the sentence in which
they appear. When adjustments are in tables, the (R) follows the designated adjustment.
Report only those adjustments made and designated with (R).
3. Calibration Description. TI parameters and performance specifications which
pertain to this calibration are listed in table 1.
Table 1. Calibration Description
Test Instrument Parameters
Performance Specifications
Dynamic range
Single channel: 90 dB 910 MHz to 9.0 GHz
85 dB (9 to 18 GHz)
Dual channel:
>100dB (10 MHz to 19 GHz)
System accuracy
(0.02 dB/10dB)
Frequency range:
Low band
10 MHz to 2.0 GHz
High bank
2 to 18 GHz
EQUIPMENT REQUIREMENTS
calibration procedure. This equipment is issued with Secondary Reference Calibration
Standards Set NSN 4931-00-621-7878 and is to be used in performing this procedure.
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.