TM 11-6625-596-12
Control indicator, or fuse
Function
NOISE GENERATOR
METER SENSITIVITY
INSULATION RESISTANCE
DIAL SPEED
DIAL BREAK
When depressed, changes mode of operation from calibrate to test. Used with
TEST button..........................................
..............................................................
DIAL SPEED, DIAL BREAK, INSULATION RESISTANCE, and HAND
Filter buttons: ........................................
..............................................................
Connect bandpsr filters between microphone preamplifier output and meter
amplifier input for frequency response measurements. Used with
EARPHONES, MICROPHONES CARBON, MICROPHONES OTHER
TYPES, and SOUND POWER TELEPHON!E switches.
Filter frequencies
1 LOW. ................................................
1 LOW ........................................................... 300 to 1,100 Hertz
2 CENTER ...........................................
2CENTER...................................................... 1,100 to 2,200 Hertz
3 HIGH .................................................
3 HIGH .......................................................... 2,200 to 5,100 Hertz
4 NARROW BAND ..............................
4 NARROW BAND ........................................ 97 to 1,02 Hertz
READ MICROPHONE CURRENT
button. ...................................................
When depressed together with MICROPHONES CARBON button, panel
meter indicates bias current to microphone (meter reading is arbitrary and
MICROPHONE CURRENT control .......
not true current) in amperel
Varies de bias current to carbon microphone connected to MICROPHONES
TEST CONDITION switch ...................
Depending on test being performed, connects measuring circuitry to:
Position
Connected to
COUPLER ............................................ Coupler.
ART REC.............................................. ARTIFTCIAL RECEIVER terminals.
..............................................................
TEL LINE....................................................... TEL LINE terminals.
Connects output of power amplifier to:
Position
Connected to
LOAD ................................................ Resistive load.
DRIVER................................................ Test loudspeaker.
PANEL TERMINALS ............................ NOISE GEN panel terminals
RECEIVER LOAD switch. ....................
Selects resistive pad that most nearly matches impedance of earphone being
MICROPHONE LOAD switch................
tested.
LONG LINE and SHORT LINE .............
microphone being tested.
buttons. .................................................
Simulates long-line and short-line load conditions for telephone to TEL LINE
Continuity test lamp terminal L1 and L2. Used in telep hone efficiency and varistor
tests.
LEVEL controls A and B .......................
TEST LEADS terminals.
..............................................................
Attenuates output of microphone preamplifier before it reaches meter
VALUE controls C and D ......................
amplifier.
Further attenuates output of microphone preamplifier after it ha passed
through filters. Attenuator C folows output of center bandpss filter,
while attenuator D attenuates output of high bandpass filter. Used
primarily to determine frequenc y response of transducers. Also used in
11V 318 A. SLO. BLO. fuses ............
telephone efficiency and varistor tests.
230V 3/16 A. SLO. BLO. fuses .........
Powerline fuses. Protect equipment from damage caused by short circuits.
1/16 amp slo-blo fuse .........................
Powerline fuses. Protect equipment from damage caused by short circuits.
(1A3Fl, fuse. 4-1). ................................
20-hertz inverter circuit fuse. Protects 20-hertz inverter from damage.
a. Common battery
b Common-battery signal.
c. Local battery.
2-6