TM-9-2350-275-BD

M113 FAMILY CARRIER, PERSONNEL SELF-PROPELLED FULL-TRACKED

TECHNICAL MANUAL; OPERATORS, ORGANIZATIONAL, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE; BATTLEFIELD DAMAGE ASSESSMENT AND REPAIR

TM-9-2350-275-BD - Page 197 of 223

TM 9-2350-275-BD

APPENDIX B

SECTION III. Test Equipment

B-3. FIELD EXPEDIENT TEST EQUIPMENT

General Information:

Sometimes, in the process of assessing the battlefield damage, it is necessary to make

voltage and resistance measurements to determine where the fault is. Standard test

equipment (voltmeter, ohm meter, SWR meter, etc.) should be used whenever possible.

If standard test equipment is not available, field expedient equipment can be fabricated

using parts commonly found on the vehicle and in the forward maintenance areas. The

following paragraph provides fabrication instructions for making a voltmeter,

ohmmeter, and RF transmitter output tester.

NOTE

Accurate measurements are not available. These are Go - No-Go meters.

1.

Making a Voltmeter.

A voltmeter can be made

from a light bulb and two pieces of wire.

The pieces of wire can be connected to

the case and center terminal of the

bulb by means of solder, twisting, or

simply holding the wire ends against

the bulb (see illustration). The voltage

rating of the bulb should be close to

the value of the expected voltage being

measured. For voltages in the 18 to 30

vdc range, any light bulb on the driver’s

master panel, driver's instrument panel,

gunner’s panel, commander’s panel, or

gunner’s primary sight can be used. For

voltages of 5 vdc or less a two-battery

cell flashlight bulb can be used. The

presence of voltage will cause the bulb to

glow. Polarity of dc voltage does not have

to be observed; even ac voltage can be measured.

Twist exposed wire ends together and apply

solder, if available, and solder. Touch to

voltage source when ready to make measurement.

B-7