Wavetek 29 Service Manual

MAINTENANCE MANU AL

Model 29

10 MHz DDS

Function Generator

© 1997 Wavetek Ltd

This document contains information proprietary to
Wavetek and is provided solely for instrument
operation and maintenance. The information in this
document may not be duplicated in any manner
without the prior approval in writing from Wavetek.

Wavetek Ltd

Test and Measurement Division

Hurricane Way

Norwich Airport Industrial Estate

Norwich, Norfolk NR6 6JB, U.K.

Tel: [phone]

Fax: [phone]

Manual Issue: 1.1

Manual Part Number:

Table of Contents

Specifications 2

Safety 6

EMC 7

Installation 7

General 9

Circuit Descriptions 10

Calibration 15

Parts List 18

Circuit Diagrams 25

1

Specifications

Specifications apply at 18°-28°C after one hour warm-up, at maximum output into 50Ω

WAVEFORMS

STANDARD

Sine, square, positive pulse, negative pulse, multi-level squarewave, triangle, ramp up, ramp
down, DC and pseudo-random noise.

ARBITRARY

Sampling Frequency:
Waveform Length:: 1024 points maximum
Vertical Resolution: 10 bits

FREQUENCY

Frequency ranges for standard waveform are listed below. In Arbitrary mode all waveform points
are output up to approximately 27 kHz beyond which they are sampled.

Sine: 100 µHz to 10 MHz
Square: 100 µHz to 10 MHz
Positive/Negative Pulse: 100 µHz to 10 MHz
Triangle: 100 µHz to 100 kHz
Positive/Negative Ramp: 100 µHz to 100 kHz
Multi-level square: 100 µHz to 100 kHz
Pseudo-random noise: 30 mHz to 700 kHz
Resolution: 7 digits (limited by 100 µHz)
Accuracy: Typically 10 ppm for 1 year, 18°C to 28°C
Stability: Typically 1ppm per °C outside 18°C to 28°C

27.48MHz

WAVEFORM CHARACTERISTICS

Sine Distortion: <0.3% to 500 kHz

<-50 dBc to 1 MHz

<-35 dB to 10 MHz
Non-harmonic spurs: typically -50 dBc to 10 MHz
Square Rise/Fall Time: <25 ns
Square Aberrations: <5% + 2 mV
Square Symmetry Control: 1 to 99% (0.1% resolution) 100 µHz to 30 kHz

20 to 80% (0.1% resolution) 30 kHz to 10 MHz
Triangle Linearity Error: <0.5% to 30 kHz
Triangle Symmetry Control: 1 to 99% (0.1% resolution) 100 µHz to 100 kHz
Pulse Rise/Fall Time: <25 ns
Pulse Aberrations: <5% + 2 mV
Pulse Symmetry Control: 1 to 99% (0.1% resolution) 100 µHz to 30 kHz

20 to 80% (0.1% resolution) 30 kHz to 10 MHz
Multi-level Square: Maximum of 16 steps of discrete amplitude and duration (1 to 1,024

points). Allows generating 3 level square, staircase, multiplexed

LCD driver signals, etc.

2

OUTPUT CHARACTERISTICS

Output Impedance:
Amplitude:

DC Offset:

Resolution: 3 digits (limited by 1 mV)
Accuracy:
Flatness: ±0.2 dB to 500 kHz, ±1 dB to 5 MHz, ±2.5 dB to 10 MHz

50Ω or 600Ω switchable

2.5 mVpp to 10 Vpp into 50Ω/600Ω
5 mVpp to 20 Vpp into open circuit

±5V (limited by offset plus signal peak) into 50Ω/600Ω
±10V (limited by offset plus signal peak) into open circuit

3% + 1 mV at 1 kHz into 50Ω/600Ω

OPERATING MODES

CONTINUOUS

Continuous cycles of the selected waveform are output at the programmed frequency.

TRIGGER/BURST

Phase coherent triggering of the programmed number of cycles of the selected waveform.
Waveforms start and stop at the phase angle specified in the Start/Stop phase parameter.

Trigger Sources: External signal, manual (front panel key), internal trigger generator or

remote command.
Burst Count: 1 to 1023 cycles
Trigger Repetition Rate: dc to 50 kHz (internal trigger generator)

dc to 1 MHz (external trigger signal)

GATE

Cycles of the selected waveform are continuously output while the trigger signal is present.

Trigger Sources: External signal, manual (front panel key), internal trigger generator or

remote command
Trigger Repetition Rate: dc to 50 kHz (internal trigger generator)

dc to 1 MHz (external trigger signal)

SWEEP

Sweep Mode: Linear or logarithmic, single triggered cycle or continuous
Frequency Range: 100 µHz to the maximum frequency for selected waveform
Markers: Two variable markers during sweep
Trigger Sources: External signal, manual (front panel key), or remote command

FREQUENCY HOP

Up to 16 different hop waveforms, each with independently setable frequency, amplitude, offset,
waveform (except noise), and duration for each waveform. Phase continuous switching between
frequencies can be executed via software or manually (front panel key). Waveform duration can
be set from 2 ms to 65 s in 1 ms increments. HOP can be externally triggered from the EXT TRIG
input.

3

AMPLITUDE MODULATION

Carrier Frequency Range 100 µHz to the maximum frequency for selected waveform.

Carrier Waveforms: All
Depth: Typically variable from 0% to 100% in 1% increments
Internal Source: 1 kHz fixed sinewave or 5 mHz to 50 kHz squarewave
External Source: DC to 100 kHz (4 quadrant)
External Sensitivity: Approximately 2 Vpp for 50% modulation

FREQUENCY SHIFT KEYING (FSK)

Phase coherent switching between two selected frequencies at a rate defined by the switching
signal source.

Carrier Frequency: 100 µHz to the maximum frequency for selected waveform
Carrier Waveforms: All
Switch Repetition Rate: dc to 50 kHz (internal trigger generator)

dc to 1 MHz (external trigger signal)

Switching Signal Source: Internal from front panel key or internal trigger generator

External from Trig/Gate input or remote interface

START/STOP PHASE

Phase relationship between MAIN OUT and AUX OUT is determined by the START/STOP
PHASE setting.

Carrier Frequency: 100 µHz to 1 MHz
Carrier Waveforms: All
Range: 0 to 360 degrees
Resolution: 1 degree

TRIGGER GENERATOR

Internal source 5 mHz to 50 kHz squarewave adjustable in 20 µs steps with 3 digit resolution.
Available for output at the sweep/marker connector (except during sweep or HOP operation).

OUTPUTS/INPUTS

FRONT PANEL CONNECTIONS

MAIN OUT

AUX OUT: CMOS/TTL level signal at the frequency and symmetry of main output.

EXT TRIG: External trigger input for Trigger, Gate, Sweep and FSK operating

Waveform output at 50Ω or 600Ω (selectable) impedance.
Short circuit protection for up to 60 seconds is provided.

Phase relationship between MAIN OUT and AUX OUT is determined
by the START/STOP PHASE setting.

modes. It is also used to synchronize one Model 29 (as a slave) to
another Model 29 (as a master).
Maximum input voltage is ±10V.

4

REAR PANEL CONNECTIONS

CLOCK IN/OUT The function of the CLOCK IN/OUT connector is set from the front

panel SYS (system) menu as follows:
CLOCK IN The connector serves as an input for an external clock
CLOCK OUT This is the default setting. The internal clock is made available as an

output. When two or more Model 29s are synchronized the CLOCK

OUT is used as a master to drive the CLOCK IN of the slave units.
PHASE LOCK For use as a slave unit phase locked to the master unit.
VCA IN Input connector for externally controlled Amplitude Modulation (AM).

Impedance is nominally 6 kΩ.
SYNC OUT When two or more generators are syncronized the SYNC OUT

connector on the master generator is connected to the EXT TRIG

inputs of the slave generators. SYNC OUT logic levels are nominally

0V and 5V with 50Ω output impedance.
TRIG/SWEEP OUT The function of this output is automatically determined by the generator

operating mode. Except in sweep and HOP modes the output is that of

the internal trigger generator, a fixed amplitude squarewave whose

frequency is set in the TRIG of GATE menus. The rising edge of the

trigger generator initiate trigger, gate and burst modes. In sweep mode

the output is a 3-level waveform, changing from high (4V) to low (0V) at

the start of the sweep, with narrow 1V pulses at marker points. In HOP

mode the output goes low on entry to each waveform step and high

after the new frequency and waveshape of that step have been set.

Output impedance is 1kΩ.

INTERFACES

Full remote control facilities are provided through RS232 and IEEE-488 (GPIB) interfaces.

RS232: Variable baud rate, 9600 baud max;, 9-pin D connector.
IEEE-488: Conforms with IEEE-488.1 and IEEE.488.2

STORED SETTINGS

Up to 9 complete instrument set-ups may be stored and recalled from battery backed memory.

GENERAL

Display: 20 character by 4 row alphanumeric display.
Size: 130 mm (height), 212 mm (width), 330 mm (depth)
Weight: 9 pounds (4.1 kg)
Power 115 V or 230 V nominal 50/60 Hz, adjustable internally,

operating range ±14% of nominal, 30 VA maximum.
Operating Range: 5°C to 40°C, 20-80%RH
Storage Range: -20°C to 60°C
Options: 19” Rack Mount Kit
Safety: Complies with EN61010-1
EMC: Complies with EN55011 and EN50082-1.

5

Safety

This function generator is a Safety Class I instrument according to IEC classification and has
been designed to meet the requirements of EN61010-1 (Safety Requirements for Electrical
Equipment for Measurement, Control and Laboratory Use). It is an Installation Category II
instrument intended for operation from a normal single phase supply.

This instrument has been tested in accordance with EN61010-1 and has been supplied in a safe
condition. This service manual contains some information and warnings which have to be
followed by the user to ensure safe operation and to retain the instrument in a safe condition.

This instrument has been designed for indoor use in a Pollution Degree 1 environment (no
pollution, or only dry non-conductive pollution) in the temperature range 5°C to 40°C, 20% - 80%
RH (non-condensing). It may occasionally be subjected to temperatures between +5° and -10°C
without degradation of its safety.

Use of this instrument in a manner not specified by these instructions may impair the safety
protection provided. Do not operate the instrument outside its rated supply voltages or
environmental range. In particular excessive moisture may impair safety.

WARNING! THIS INSTRUMENT MUST BE EARTHED

Any interruption of the mains earth conductor inside or outside the instrument will make the
instrument dangerous. Intentional interruption is prohibited. The protective action must not be
negated by the use of an extension cord without a protective conductor.

When the instrument is connected to its supply, terminals may be live and opening the covers or
removal of parts (except those to which access can be gained by hand) is likely to expose live
parts. The apparatus shall be disconnected from all voltage sources before it is opened for any
adjustment, replacement, maintenance or repair.

Any adjustment, maintenance and repair of the opened instrument under voltage shall be avoided
as far as possible and, if inevitable, shall be carried out only by a skilled person who is aware of
the hazard involved.

If the instrument is clearly defective, has been subject to mechanical damage, excessive moisture
or chemical corrosion the safety protection may be impaired and the apparatus should be
withdrawn from use and returned for checking and repair.

Make sure that only fuses with the required rated current and of the specified type are used for
replacement. The use of makeshift fuses and the short-circuiting of fuse holders is prohibited.

This instrument uses a Lithium button cell for non-volatile memory battery back-up; typical life is 5
years. In the event of replacement becoming necessary, replace only with a cell of the correct
type, i.e. 3V Li/Mn0
in accordance with local regulations; do not cut open, incinerate, expose to temperatures above
60°C or attempt to recharge.

Do not wet the instrument when cleaning it and in particular use only a soft dry cloth to clean the
LCD window. The following symbols are used on the instrument and in this manual:-

l

20mm button cell type 2032. Exhausted cells must be disposed of carefully

2

Caution - refer to the accompanying documentation, incorrect
operation may damage the instrument.

terminal connected to chassis ground.

mains supply OFF.

mains supply ON.

6

alternating current.

This function generator has been designed to meet the requirements of the EMC Directive
89/336/EEC.

Compliance was demonstrated by meeting the test limits of the following standards:

Emissions

Immunity

Cautions

To ensure continued compliance with the EMC directive the following precautions should be
observed:

EMC

EN55011 (1991) for industrial, scientific and medical (ISM) radio-frequency equipment;
Group 1 Class B limits were applied.

EN50082-1 (1992) Generic immunity standard for residential, commercial and light
industry. Test methods and limits used were:

a) EN60801-2 (1993) Electrostatic Discharge, 8 kV air discharge.

b) IEC801-3 (1984) RF Field, 3 V/m.

c) IEC801-4 (1988) Fast Transient, 1 kV peak.

a) connect the generator to other equipment using only high quality, double-screened cables.

b) after opening the case for any reason ensure that all signal and ground connections are

remade correctly before replacing the cover. Always ensure all case screws are correctly
refitted and tightened.

c) In the event of part replacement becoming necessary, only use components of an identical

type, see the Parts List.

Installation

Check that the instrument operating voltage marked on the rear panel is suitable for the local
supply. Should it be necessary to change the operating voltage, proceed as follows:

1) Disconnect the instrument from all voltage sources.

2) Remove the screws which retain the top cover and lift off the cover.

3) Change the transformer connections as follows:
for 230V operation connect the live (brown) wire to pin 15
for 115V operation connect the live (brown) wire to pin 14
for 100V operation connect the live (brown) wire to pin 13.

4) Refit the cover and the secure with the same screws.

5) To comply with safety standard requirements the operating voltage marked on the rear panel

must be changed to clearly show the new voltage setting.

6) Change the fuse to one of the correct rating, see below.

7

Fuse

Ensure that the correct mains fuse is fitted for the set operating voltage. The correct mains fuse
types are:

for 230V operation: 250 mA (T) 250 V HRC
for 110V/115V operation: 500 mA (T) 250 V HRC

To replace the fuse, disconnect the mains lead from the inlet socket and release the fuse drawer
below the socket pins by depressing both clips together, with miniature screwdrivers, so that the
drawer can be eased open. Change the fuse and replace the drawer.

The use of makeshift fuses or the short-circuiting of the fuse holder is prohibited.

Mains Lead

When a three core mains lead with bare ends is provided it should be connected as follows:-

Any interruption of the mains earth conductor inside or outside the instrument will make the
instrument dangerous. Intentional interruption is prohibited. The protective action must not be
negated by the use of an extension cord without a protective conductor.

Mounting

This instrument is suitable both for bench use and rack mounting. It is delivered with feet for
bench mounting. The front feet include a tilt mechanism for optimal panel angle.

A rack kit for mounting one or two of these Half-width 3U high units in a 19” rack is available from
the Manufacturers or their overseas agents.

Brown - Mains Live

Blue - Mains Neutral

Green / Yellow - Mains Earth

WARNING! THIS INSTRUMENT MUST BE EARTHED

8

Service Handling Precautions

Service work or calibration should only be carried out by skilled engineers. Please note the
following points before commencing work.

Most of the integrated circuits are CMOS devices and care should be taken when handling to
avoid damage by static discharge.

Many of the devices are miniature surface mount components with very fine leads on small
pitches; these components must be removed and replaced with great care to avoid damage to
the pcb. It is essential that only tools and soldering equipment specifically designed for surface
mount components are used.

The decoupling capacitors associated with the integrated circuits are surface mounted on the
solder side of the pcb.

Dismantling the Instrument

Disconnect the instrument from all voltage sources before it is opened for adjustment or repair. If
any adjustment or repair of the opened instrument is inevitable it shall be carried out only by a
skilled person who is aware of the hazards involved.

General

WARNING

1. Remove the six screws retaining the top cover.

2. The rear panel may be removed as follows. Disconnect the gray ribbon cable from PJ4
on the GPIB pcb and remove the 2 screwjacks which secure the RS232 connector to the
rear panel. Invert the instrument and remove the three screws securing the rear panel;
the panel may now be tilted back to allow access. If the panel is to be completely
removed unplug connectors from PJ4, PJ7 & PJ8 and the blue and brown wires from the
mains inlet filter; desolder the blue and brown wires from the mains transformer. The
panel can now be lifted free of the instrument.

3. The front panel assembly may be removed as follows. Unplug the connectors from PJ2,
PJ3, PJ5 & PJ6 and desolder the screened cable from PJ10. Remove the nut securing
the front panel earthing strap and the four nuts securing the front panel assembly. The
panel may now be drawn clear of the instrument.

4. Main pcb removal. Remove all connectors from the pcb and desolder the screened cable
from PJ10. Tilt the rear panel back as described in 2 above. Remove the pcb fixing screw
nearest PJ10; invert the instrument and remove the 5 screws retaining the pcb fixing
pillars to the case lower. The main pcb can now be lifted free, complete with its fixing
pillars.

5. When re-assembling the instrument ensure that the correct fastenings are used.

9