TB 9-6625-136-24
IDENTIFICATION AND DESCRIPTION
This bulletin provides instructions for the
1. Test Instrument Identification.
calibration of Megohmmeter, Tegam, models R1M-A and R1M-AR. 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. Older models manufactured by PPM Instruments are now
manufactured by Tegam with the same specifications. R1M-AR (Army) and R1M-A (Navy)
have the same specifications. R1M-AR+850 adds two model 850 surface resistance probes
that are not calibrated (CNR).
b. Time and Technique. The time required for this calibration is approximately 0.5
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 750-25.
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
Test Voltage
Range: 50, 100, 250, 500 V dc
Accuracy: 3% of setting
Range: 1, 10, 100 M , 1, 10, 1001 G
Range Ohms
Accuracy: 5% of reading
1 Not verified above 10 G
due to standards limitations.
EQUIPMENT REQUIREMENTS
calibration procedure. This equipment is issued with Secondary Transfer Calibration
Standards Set AN/GSM-286; AN/GSM-287; or AN/GSM-440. 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
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 parentheses.
Table 2. Minimum Specifications of Equipment Required.
Manufacturer and model
Common name
Minimum use specifications
(part number)
Range: 50 to 500 V dc
Fluke, Model 8846A (8846A/G)
Accuracy: 0.75%
RESISTANCE STANDARD #1 Range: 50 k
IET Labs, HARS-LX-9-0.001
Accuracy: 1.25%
(HARS-LX-9-0.001)
RESISTANCE STANDARD #2 Range: 1 M to 10 G
IET Labs, HRRS-Q-4-1M-10KV-RM
Accuracy: 1.25%
(HRRS-Q-4-1M-10KV-RM)