HP TM 11-6625-2779-14&P - Manual (Page 25)

Model 3555B Section III
Table 3-3. Level Measurement
STEP PROCEDURE
1. Turn the 3555B/ON and depress the
DIAL/BAT pushbutton. The meter should
indicate in the green BAT GOOD area. If it
does not, replace the battery or check the
power source before attempting to make any
measurements. The battery test operates for
internal battery, office battery or ac power
source.
2. Select either TMS BRDG or TMS TERM,
depending on the measurement being made.
The weighting filters are not in the circuit at
this time.
3. Select the impedance (FUNCTION
pushbutton) to match the circuit to be tested.
Select either 900 BAL or 600 BAL (VF/Nm) for
frequencies between 20Hz and 20kHz. Select
600 BAL or 135 BAL (CARRIER) for balanced
measurements between 1 kHz and 600kHz.
Select 75 UNBAL for 75 ohm unbalanced
measurements between 30Hz and 3MHz.
4. Set the RANGE switch to +30dBm. Set the
RESPONSE switch to DAMP.
5. Connect the set to the line using a suitable
patch cord. For balanced measurements use
a cord having a 309 or 310 single plug, a 241
dual plug or banana plugs, bare wires or clip
leads. For unbalanced carrier measurements
(75 ohm only) use a cord having a 358 plug.
NOTE
Carrier measurements are
limited to the -50dBm RANGE
thru the +10dBm RANGE.
6. Down range the RANGE switch for an on-
scale indication. Level is equal to the
algebraic sum of the black RANGE setting
plus the black meter scale indication.
EXAMPLES:
RANGE = -50dBm
METER = +1dBm
LEVEL = -49dBm
RANGE = +20dBm
METER = -4dBm
LEVEL = +16dBm
Table 3-4. Noise Metallic Measurements
STEP PROCEDURE
1. Turn the POWER switch to ON and depress
the DIAL/BAT pushbutton. The meter should
indicate in the green BAT GOOD area. If it
does not replace the battery or check the
power source. The battery test operates on
internal battery, office battery or ac power
source.
2. Select either NOISE TERM or NOISE BRDG,
depending on the measurement being made.
3. Select the impedance to match the circuit to
be tested using the FUNCTION pushbuttons.
The 900 BAL VF/Nm pushbuttons only should
be used for noise metallic measurements in
the frequency range of 20Hz to 20kHz. The
HOLD function can be used in NOISE TERM
if desired.
4. Select the appropriate weighting filters using
the NOISE WTG switch.
5. Set the RANGE switch to 110dBrn.
6. Connect the set to the circuit to be tested
using a suitable patch cord and down range
for an on-scale indication.
7. Observe the meter fluctuations for two or
three minutes and take a reading where the
meter pointer appears to be most of the time,
disregarding any occasional peaks.
NOTE
For rapidly fluctuating noises
such as atmospheric noise or
switching noise, operate the
RESPONSE switch to DAMP
and read the level of the most
frequently occurring peaks.
8. Noise level is equal to the sum of the blue
RANGE switch setting in dBrn and the
indication on the blue meter scale in dBrn.
EXAMPLE:
RANGE = 40dBrn
METER = +5dBrn
NOISE LEVEL = +45dBrn
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