ADVANTEST U3751 Service Manual

U3751

U3751
Spectrum Analyzer

Compact Size and High Performance

An 8 GHz Spectrum Analyzer Based on a New Concept

●

Frequency range: 9 kHz to 8 GHz

●

High throughput, twice as fast as our conventional models

●

High accuracy: ±0.8 dB between 10 MHz and 3.1 GHz

●

Standard configuration includes:

10 MHz to 8 GHz pre-amplifier

Two-channel USB interface

LAN port

The U3751 is a portable 8 GHz
spectrum analyzer that can be
used in digital appliance produc­tion lines, in installation and
maintenance of CATV and wire­less LAN hotspots, and for a va­riety of other purposes.
The U3751 provides high-speed
throughput twice

*

1

as high as
that provided by our conventional
models. It also contributes to
reduced tact time, an important
consideration in equipment in­stallation on production lines.

Conventional system
throughput time of 875
ms is reduced by more
60%

*

1

to 350 ms in the

U3751 (on GPIB)

*

2

. This
increased speed helps
greatly to reduce test costs
on production lines and
other facilities.

Calibration is an essential requirement for improved accuracy
of measurement data. With the latest techniques in circuit in­tegration, the U3751 requires less calibration time and fewer
calibration steps.

High Throughput

High Speed Calibration

With a digital IF section and ADVANTEST's original circuit
technologies, the U3751 provides remarkably high overall am­plitude accuracy:

±0.8 dB (10 MHz to 3.1 GHz)
±1.0 dB (3.1 to 8 GHz)

Upper limits and lower limits can be set for limit lines on the
U3751 screen, thereby enabling the discriminator to make
PASS/FAIL judgments on trace data.

Higher Overall Amplitude Accuracy

PASS/FAIL Judgment

Measuring time

Measuring

time

Our conventional model

ADC Digital RBW Digital Det

Digital IF Block

RF Input

2

U3751-1E Jan. ’05

With a digital interface, the
U3751 has superb power meas­urement repeatability, guarantee­ing a overall amplitude accuracy
of ±0.8 dB or better. In addition,
the U3751 is designed to operate
with batteries and warm up with­in five minutes, offering ease of
use outdoors and in the field.

In its standard configuration, the
U3751 has a built-in pre-amplifier
for boosting the signal level to a
maximum of 8 GHz. This helps in
analysis of faint signals of 5 GHz or
more, such as those in wireless LAN,
ETC, or similar systems.

Noise level:

-135 dBm at 5 GHz, typ. (Pre-Amp. ON)

The U3751 supports three types of power: AC (100 V/200 V),
DC (+11 V to +17 V), and power from a battery pack. The
battery pack can be detached and easily replaced with a spare.

Highly Sensitive Measurement

Operating Time of 2.5 Hours

*

3

with the Battery Pack

The U3751 can warm
up within five minutes.
It requires less time to
reach its operating tem­perature and can quickly
be prepared for highly
accurate measurement.

A screenshot can be saved to a USB memory device by simply
specifying USB as the COPY device using soft keys. The
U3751 supports the BMP and PNG formats for saving data.
This feature enables measurement data to be gathered and pas­ted into reports in a PC environment. (USB version 1.1 is
supported.)

Five-Minute Warm-Up

USB Interface Included in the Standard Configuration

Time

Stable measurement

*1: Comparison with our conventional models
*2: In a sample setup where channel power measurement results are transferred with

certain frequency and span settings specified

*3: Typical value at room temperature and without any option attached

Our conventional
model

5

min.

U3751-1E Jan. ’05

3

4

U3751-1E Jan. ’05

Functions for Full-Fledged Analysis

RMS Detection Supported

For more accurate power measurement of broadband modula­tion, the U3751 supports RMS detection as well as conven­tional sample detection. With RMS detection and digital IF
technology, the U3751 is a portable spectrum analyzer capable
of highly accurate power measurement.

The U3751 is a complete spectrum analyzer containing all of
our high-frequency measuring technologies. It combines the
analysis functions of a full-featured spectrum analyzer with ease
of operation. The U3751 can handle all kinds of measurement
demands on its own.

Three-Trace Independent Detection

The U3751 has a function for displaying three independent
traces performed simultaneously and a variety of wave-detec­tion modes (RMS, peak, sample, et al.). The combination of
the function and the calculation methods listed above facili­tates such tasks as antenna adjustments.

Pre-Amplifier for Signal Boosts up to 8 GHz

The U3751 includes a pre-amplifier for boosting the signal
level to a maximum of 8 GHz, enabling highly sensitive mea­surement.

Noise level: -135 dBm at 5 GHz typ. (Pre-Amp. ON)

Channel Setting Function

The channel setting function is useful for measuring telecom­munication and broadcast channels over radio waves. The
U3751 has two types of channel setting methods: calculation
and table. The channel setting function can handle differences
among broadcast channels in various countries.

ISDB-T channel power measurement sample Sample of simultaneous Posi/RMS/Sample traces

Measurement sample of a faint 5.8 GHz signal Bluetooth channel measurement sample

U3751-1E Jan. ’05

5

Various Measurement Functions

Harmonics Measurement Function

The harmonics measurement function of the U3751 is suitable
for high-frequency testing of radio devices. With input of the
frequency of a fundamental wave or setting of a marker, the
U3751 can easily be used to make a high-frequency measure­ment.

Marker functions:

Multi-marker (10 markers)/delta marker/peak search

Different types of detectors:

Normal, Posi, Nega, Sample, RMS

Zoom Functions

A window and F-F mode are used for easy analysis of a specific
signal from a broadband measurement. RBW settings can be
changed, so broadband and narrowband analyses of measured
signals can be performed quickly. In addition, F-T mode, T-T
mode, and other types of signal analysis are available.

ACP Measurement Function

This function measures ratios between carrier power and adja­cent channel power. Up to five adjacent channels can be speci­fied, and channel bands can be specified.

Spectrum Emission Mask Function

PASS/FAIL judgment made with spectrum masks or limit lines
is a good way to increase productivity in the production of dig­ital appliances. The Spectrum Emission Mask (SEM) function
facilitates measurement of licensed radio waves on wireless
LANs and other media.

Other measurement functions:

Channel power, Total power, Average power, OBW, ACP,
Spectrum emission mask, Spurious measurement, Noise-Hz
conversion, frequency counter, and more

Sample of harmonic distortion measurement on a transmitter with a 400 MHz

bandwidth

Dual-window broadband and narrowband measurement sample

3GPP ACLR measurement sample IEEE802.11b S.E.M measurement sample

6

U3751-1E Jan. ’05

Specifications

Frequency

Frequency range: 9 kHz to 8 GHz

Frequency band: 9 kHz to 3.1 GHz (Band 0)

3.0 to 8 GHz (Band 1)

Preamplifier: 10 MHz to 8 GHz

Frequency reference

Aging: 2 x 10

-6

/year

Temperature stability: 2.5 x 10

-6

(0 to 50°C)

Frequency counter

Resolution: 1 Hz to 1 kHz

(RBW: <100 kHz, input signal level: >-50 dBm,
CW and single signal)

Frequency stability

Residual FM (zero span): <60 Hz p-p/100 ms

(internal frequency reference)

Frequency span

Range: 0, 10 kHz to Full

Accuracy: <±1% of Span
Spectrum purity: -85 dBc/Hz, offset: 10 kHz; span: <200 kHz
Resolution bandwidth

Range: 300 Hz to 3 MHz (1-3 steps)

RBW accuracy: ±12%
Video bandwidth range: 10 Hz to 3 MHz (1-3 steps)

Sweep

Sweep time

Sweep time: 20 ms to 1000 s (spectrum mode)

50 µs to 1000 s (zero span)

Accuracy: <±2% (zero span)
Sweep mode: REPEAT, SINGLE
Trigger

Source: Free, Video, EXT, IF

Amplitude range

Measurement range: Noise to +30 dBm
Maximum input level: Input attenuator: ≥10 dB

+30 dBm (preamplifier off)
+13 dBm (preamplifier on)

±15 VDC max.
Input attenuator range: 0 to 50 dB by 10 dB steps
Display range: 100, 50, 20, 10, 5 dB, Linear
Unit: dBm, dBmV, dBµV, dBµVemf, dBpW, W, V
Reference level range: -140 to 40 dBm
Detector: Normal, Posi-peak, Nega-peak, Sample, RMS

Amplitude accuracy

Calibration signal

Frequency: 20 MHz
Level: -20 dBm
Accuracy: ±0.3 dB

Scale fidelity

Log: ±0.5 dB/10 dB

±0.5 dB/80 dB

±0.2 dB/1 dB
Level measurement accuracy:After Cal., preamplifier: off;

temperature range: 20 to 30°C;

input attenuator: 10 dB; REF: 0 dBm;

and input signal level: -10 to -50 dBm

±1.5 dB (

9 kHz to 10 MHz)

±0.8 dB (

10 MHz to 3.1 GHz)

±1.0 dB (

3.1 to 8 GHz)

Dynamic range

Displayed average noise level: Frequency: 10 MHz to 8 GHz;

Ref. level: <-45 dBm; RBW: 300 Hz
Band 0, preamplifier: off: -118 dBm + 2 f (GHz) dB
Band 1, preamplifier: off: -117 dBm + 1 f (GHz) dB
Band 0, preamplifier: on: -133 dBm + 3 f (GHz) dB
Band 1, preamplifier: on: -134 dBm + 1.3 f (GHz) dB

Gain compression (1 dB): Frequency: 10 MHz to 8 GHz

Preamplifier: off: >-8 dBm
Preamplifier: on: >-25 dBm

Second harmonic distortion: <-70 dBc (preamplifier: off;

mixer level: -40 dBm; frequency: >200 MHz)

<-75 dBc typ. (preamplifier: off;

mixer level: -30 dBm; frequency: >300 MHz)

Third order intermodulation: -50 dBc (frequency: 10 MHz to 8 GHz;

preamplifier: off; mixer level: -20 dBm;

2-signal separation: 200 kHz)

Image/Multiple/
Out-of-band response: <60 dBc (image suppression: ON)
Residual responses: <-80 dBm (frequency: 10 MHz to 8 GHz;

preamplifier: off)

Inputs/Outputs

RF Input

Connector: N type female
Impedance: 50Ω (nominal)
VSWR:

<1.7 : 1 (<3.0 GHz), input attenuator: >10 dB

<2.0 : 1 (>3.0 GHz), input attenuator: >10 dB

Calibration output

Connector: BNC female
Impedance: 50Ω (nominal)
Frequency: 20 MHz
Level: -20 dBm

Frequency reference input

Connector: BNC female
Impedance: 50Ω (nominal)
Frequency [MHz]: 1, 1.544, 2.048, 5, 10, 12.8, 13, 13.824, 14.4,

15.36, 15.4, 16.8, 19.2, 19.44, 19.6608,

19.68, 19.8, 20, 26

Level: 0 to +16 dBm

External trigger input

Connector: BNC female
Impedance: 10 kΩ (nominal), DC coupled
Trigger level: 0 to +5 V

21.4 MHz IF Output
Connector: BNC female
Impedance: 50Ω (nominal)
Level:

Approx. mixer input level: +10 dB (at 20 MHz)

Battery mount

Connector: Antonbauer QR mount

External DC input

Connector: XLR-4
Voltage range: +11 to +17 V

GPIB: IEEE-488 bus connector
USB: USB1.1
Video output Connector: D-sub 15-pin female
LAN Connector: RJ45 type, 10/100 base -T

General specifications

Operating environment range

Temperature: 0 to +50°C
Humidity: Relative humidity: 85% or less

(without condencation)

Storage environment range:

-20 to +60°C, Relative humidity: 85% or less

AC power input:

Automatic switching to 100 VAC or 200 VAC
100 VAC: 100 to 120 VAC, 50/60 Hz

200 VAC: 200 to 240 VAC, 50/60 Hz
DC power input: DC: +11 to +17 V
Power consumption: 100 VA or less (A.C. operation)

70 W or less (D.C. operation)
Mass: 5.6 kg or less (without option)
Dimensions: approx. 308 (W) x 175 (H) x 209 (D) mm

(without protrusion)

approx. 337 (W) x 190 (H) x 307 (D) mm

(with handles, feet, and protectors)

U3751 Web Demonstration

More detailed information on the U3751 spectrum analyzer

and its features is available on the Internet.

Access the URL below to read it.

http://green.advantest.co.jp/techinfo_e/www_e/

demonstration_e/U3751/index.html

U3751-1E Jan. ’05

7

Option 20 High stability frequency reference

Reference frequency stability

Aging: ±2 x 10

-8

/day

±1 x 10

-7

/year

Warm-up drift (nominal): ±5 x 10

-8

(+25°C, 10 min. after turning the power on)

Temperature drift: ±5 x 10-8(0 to +40°C, with reference to 25°C)

Ordering information

Main unit

Spectrum analyzer: U3751

Accessories

Power cable: A01412
Input cable: A01037-0300
N-BNC adapter: JUG-201A/U
Ferrite core: ESD-SR-120

Option

High-stability frequency reference crystal: OPT.20
Tracking generator: OPT.74

Accessories (optional)

Battery pack: A870008
Charger: A870009
75Ω impedance converter: ZT-130NC
DC power cable: A114020
Carrying case: A129001
Transit case: A129002

Please be sure to read the product manual thoroughly before using the products.
Specifications may change without notification.

IF OUT

DC INPUT

Battery receptacle

Main function keys

Operation-key block

GPIB

EXT TRIG INPUT USB

USBPOWER CAL OUT

Soft-key block

TG OUT RF INPUT

Control keys

VIDEO OUT

EXT REF INPUT LAN

6.5-inch color liquid
crystal display (LCD)

Exclusive function keysExtension-key block

Front Panel

Rear Panel

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