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1. GENERAL
The LDM-171
is
an easy·to·use, semi-automatic
distortion meter
that
can measure
all
total
harmonic
distortion
in
audio amplifiers
and
communications
equipment.
It covers
the
entire audio band from
20Hz
to
20kHz with a high sensitivity
of
0.1% full·
scale.
An auto-tuning circuit enables distortion
to
be
measured easily even in the
1%
and lower ranges,
where manual tuning
is
difficult.
A highly sensitive
built·in millivoltmeter enables
the
LDM-171
to
function also
as
a signal-to-noise
(S/N) meter.
2.1 Distortion Measurement
Frequency ranges
Measurement ranges
Input voltage ranges
Minimum measurable
input
voltage
Maximum measurable
input
voltage
Measurement accuracy
Residual distortion
Input impedance
Filter characteristics
Fundamental suppression
Harmonic
attenuation
Auto-tuning
Capture ranges
2.2
Level
Measurement
Frequency range.
Measurement ranges
Measurement accuracy
Input impedance
2.3
S/N Measurement
Measurement range
Input voltage range
Input impedance
2.4 Common Specifications
High-pass filter
Cutoff
frequency
Roll
off
Monitor terminal
Output
voltage
Output
impedance
Power requirements
External dimensions
Ambient temperature
Accessories
2.
SPECIFICATIONS
Three ranges: 20Hz
to
20kHz
Seven ranges: 0.1%, 0.3%,
1%,
3%, 10%,30% and 100%
Four ranges: 0.35V
to
1
V,
1 V
to
3V, 3V
to
1
OV,
1
OV
to
30V
350mV
30V
±5%
of
fullscale (except
in
100% range)
0.01% max.
I
Approx.
100kn,
shunt
capacitance
50pF
max.
80d8
min.
0.6d8
max. (2nd and
3rd
harmonics)
1%,
0.3%, 0.1%
20Hz
to
200kHz
Twelve ranges (0.3,
1,
3,
10,30
and 100) in both mV
and
V
±5%
of
fullscale
1
Mn,
shunt
capacitance 50pF max.
OdB
to
80d8
Same
as
for distortion measurement
Approx. 1
OOkQ,
shunt
capacitance 50pF max.
400Hz
12d8/oct
1 Vrms
at
fullscale reading
Approx.
1kn
1
OOV
±
10%,
50/60Hz.
Alterable
to
120V, 200V or 240V by rewiring transformer taps.
300(W) x 150(H) x 250(D)mm
0°C
to
40°C
1 banana tip/alligator clip lead
Instruction manual
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2-
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