HP TM 11-6625-2779-14&P - Manual (Page 15)

Model 3555B Section III
Table 3-1. Front, Side and Rear Pane
(1) S and G Jacks: Binding posts accepting banana
plugs, spade lugs, phone tips or bare wires for
connection to the case ground (G) and sleeves (S)
of all INPUT jacks (12) and DIAL/AC MON jacks
(10) and (11).
(2) Shorting Strap: A swing-away shorting strap
connecting the S and G terminals together which
may be used to isolate the jack sleeves from case
ground. Not for use with type 347 plugs.
(3) WTG Switch: Selects weighting filters for noise
measurements. These filters are selectable only
when the INPUT switch is in one of the two NOISE
positions. The 3kHz FLAT, C-MSG, 15kHz FLAT
and PROG filters all conform to the standards set
up by the Bell System and Edison Institute for
measuring message circuit noise.
(4) RANGE SWITCH: Selects dBm or dBm ranges of
input sensitivity. The RANGE switch markings
correspond to the 0 markings on the meter scale
(6). The black markings are dBm for transmission
measurements and the blue markings are dBrn for
noise measurements.
(5) RESPONSE Switch: Selects NORM meter
response for transmission level measurements or
DAMP for noise measurements where noise is
impulsive in nature.
(6) Meter: A taut band individually calibrated meter
with shaped pole pieces to provide a linear dBm
indication with equal accuracy and resolution over
the entire meter scale. The dBm scale is marked
in black and has 0.1dB resolution for transmission
measurements. The 0 marking at the right end of
the scale corresponds to the black RANGE switch
setting. The dBm scale is marked in blue for noise
measurements. The 0 marking at the left end of
the scale corresponds to the blue RANGE switch
setting. The green arc marked BAT GOOD
corresponds to the green DIAL BAT pushbutton for
checking the power source. The left edge of the
arc corresponds to the battery cut-off voltage of 24
volts and the right edge (meter full-scale)
represents 60 volts which is the maximum voltage
that can be used to power the set without internal
damage.
(7) POWER ON/OFF Switch: turns on all power to the
set. The set operates from either 115 volts or 230
volts ac, the internal 45 volt dry cell battery or from
an external office battery supply.
(8) INPUT Switch: Selects TMS, either BRDG or
TERM for transmission measurements and NOISE,
either BRDG or TERM for noise measurements.
For noise measurements the switch must be in
Controls, Indicators and Connectors either the
NOISE BRDG or the NOISE TERM before the
NOISE WTG filters can be selected.
(9) FUNCTION Switch: A series of interlocking
pushbutton switches (with the exception of the
HOLD switch which is push-push type) with the
following functions:
a. VF/Nm
1. HOLD: Applies a dc holding bridge
across the metallic line for the NG, 900
and 600 functions. The HOLD
pushbutton is the push-push type, ie,
push to make and push to break. The
HOLD function cannot be
accomplished when any one of the
CARRIER pushbuttons is depressed.
2. DIAL/BAT: Connects the multiple
INPUT jacks in parallel with the
DIAL/AC MON jacks for the dial and
talk operation. The circuit is arranged
for loop dialing and the line under test
must supply talk battery. Connects the
meter circuit and a load to the internal
power supply to check the condition of
the battery, ac power or external office
battery as indicated on the green meter
scale. POWER (7) must be ON for the
battery test.
3. NG: Selects the noise-to-ground input
circuits for measuring longitudinal
noise. Attenuation of 40dB is inserted
by this circuit. Earth ground should be
connected to the black G binding post
(1)
4. 900: Selects the input circuitry for
balanced 900 ohm circuits. This
function selects a low frequency
transformer for voice frequencies.
Response of this transformer is 20Hz
to 20kHz.
5. 600: Selects the input circuitry for
balanced 600 ohm circuits. A low
frequency transformer is selected for
this function.
b. Carrier
1. 600: Selects the input circuitry for
balanced 600 ohm circuits. A high
frequency transformer is selected for
this function. Response of this
transformer is 1kHz to 600kHz. The
HOLD function is not operative in any
of the carrier functions.
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