Thurlby Thandar Instruments TG300 User Manual

THURLBY THANDAR INSTRUMENTS

INSTRUCTION MANUAL

TG300 Series

3MHz Function Generators

Table of Contents

Introduction 2
Specification 3
EMC 7
Safety 8
Installation 9
Operation 10
Calibration and Maintenance 13

Instructions en Francais

Sécurité 14
Installation 15
Fonctionnement 16
Calibrage et maintenance 20

Bedienungsanleitung auf Deutsch

Sicherheit 21
Installation 22
Betrieb 23
Kalibrierung und Wartung 27

Istruzioni in Italiano

Sicurezza 28
Installazione 29
Funzionamento 30
Calibrazione e Manutenzione 34

Instrucciones en Español

Seguridad 35
Instalación 36
Funcionamiento 37
Calibrado y Mantenimiento 41

1

Introduction

The TG300 series are precision 3MHz function generators with waveforms of sine, triangle, ramp.
pulse and DC from a variable amplitude 50Ω or 600Ω output. A TTL/CMOS auxiliary output is also
provided.

The frequency range is 0·03Hz to 3MHz selected by a seven decade range multiplier and
calibrated vernier. Both the frequency vernier and the sweep input can give 1000:1 frequency
change within a selected range. A 10:1 symmetry range permits ramp and pulse waveforms to be
produced.

The generator output level is 20Vpk-pk maximum from a 50/600Ω source. The level is set via a
switched attenuator plus vernier with a total range of >80dB. DC offset is vernier adjustable over
a ±10V range with centre detent for 0V. Waveform quality is good at all frequencies and signal
levels.

All models feature a large liquid crystal display shows frequency and amplitude simultaneously.
Good resolution and a fast display update rate are maintained at all frequencies.

The TG330 also has internal LIN/LOG sweep with sweep output and AM. Amplitude modulation of
up to 100% is possible using the internal 400Hz oscillator or an external source.

On the TG320 and TG330 the display can also be used as an external 120MHz frequency meter
with up to 7-digit resolution.

Additional display annunciators indicate generator status when sweep, AM, etc. are in use.

2

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

FREQUENCY

Frequency Range: 0·03Hz to 3MHz in 7 overlapping decade ranges with adjustment by vernier

Vernier Range: 1000:1 on each range.
Frequency Display: Auto-ranging reciprocal measurement giving 4-digit resolution down to 10Hz

WAVEFORMS

Waveform specifications apply for the top decade of each frequency range.

SINE

Distortion: Less than 0·5% on 300Hz, 3kHz and 30kHz ranges; less than 1% on 3Hz,

Amplitude Flatness: ± 0·2dB to 200kHz; ± 2dB to 3MHz.

Specification

control.

(to 1Hz on the 3Hz range); resolution is fixed at 0·01Hz below 10Hz
(0·001Hz below 1Hz on the 3Hz range).

Accuracy is ±1 digit to 2·1Hz (to 0·21Hz, Symmetry off, or to 0·42Hz,
Symmetry on, on the 3Hz range); below this the accuracy is ± 1% of range
full scale (unspecified with Symmetry on).

30Hz and 300kHz ranges; all harmonics >25dB below fundamental on
3MHz range.

TRIANGLE

Linearity:

Better than 99% to 200kHz.

SQUAREWAVE

Rise and Fall Times: <100ns
Mark-Space Ratio: 1:1 ±1% to 100kHz

DC

Range: ±10V (unterminated).

SYMMETRY

Symmetry Range: Variable typically between 1:9 and 9:1 (on top decade of each range),

frequency divided by 10 when Symmetry is selected.

MODULATION MODES

Modulation can be used with all waveforms and at any frequency.

Sweep

Sweep Mode: Internal (TG330 only): linear or logarithmic; sweep Start and Stop

frequencies displayed at a press of a button.

External: linear.
Sweep Width: Up to 1000:1 within each range.
Sweep Rate: Internal sweep rate adjustable from typically 20ms to 20s.
External Sweep: By signal applied by SWEEP IN/OUT socket.

3

Amplitude Modulation (TG330 only)

Modulation Depth: Variable 0 to 100% typical.
Modulation Frequency: 400Hz internal. DC to 20kHz external.
External Modulation: By signal applied to COUNT/AM IN socket.

OUTPUTS

50Ω Main Out

Output Impedance:
Amplitude:

Attenuator: 0, –20, –40 or –60dB.
DC Offset Range:

600Ω Main Out

Alternative output socket providing the same signal as the 50Ω Main Out but from 600Ω. The 50Ω
and 600Ω sockets are not independent.

Aux Out

Output Characteristics: Frequency, symmetry and phase the same as main outputs.
Output Level: 0 to 5V TTL/CMOS logic levels capable of driving 2 standard TTL loads.

Sweep Out (TG330 only)

When internal sweep is selected the sweep signal is available as a 0 to 3V ramp from 600Ω.

50Ω
2mV to 20V peak-peak open circuit (1mV to 10V peak-peak into 50Ω) in

four switch-selectable ranges with 20dB vernier control within each
range.

±10V. DC offset plus signal peak limited to ±10V (± 5V into 50Ω); CLIP
shows in display when offset + signal peak exceeds ±10V. DC offset
plus waveform attenuated proportionally by the attenuator.

INPUTS

Sweep In

The SWEEP IN/OUT socket is set to Sweep In when EXT SWEEP is selected.
Input Impedance:
Input Sensitivity: 0 to 3V for 1000:1 sweep.

Maximum Allowable

Input Voltage:
Sweep Linearity: Better than 1%
Maximum Slew Rate of

Sweep Voltage:

AM In (TG330 only)

The AM/COUNT IN socket is set to AM input when EXT AM is selected.
Input Impedance:
Input Sensitivity: Approximately 2V peak-peak for 100% modulation.

Maximum Allowable

Input Voltage:

10kΩ

±10V

0·1V/µs

40kΩ

±10V

4

Count In (TG330/TG320)

The AM/COUNT IN socket is set to external frequency measurement when EXT COUNT is

selected.
Input Impedance:
Input Sensitivity: 50mVrms (sinewave).

Maximum Allowable
Input Voltage:

1MΩ//25pF

50Vdc/50Vrms to 400Hz with respect to ground
above 1MHz.

DISPLAY FUNCTIONS

The LCD shows generator frequency simultaneously with output amplitude/offset, together with

various status annunciators. Alternatively, it is the external frequency measurement display.

Internal Measurement Accuracy

Frequency: Auto-ranging reciprocal measurement giving 4-digit resolution down to

10Hz (to 1Hz on the 3Hz range); resolution is fixed at 0·01Hz below 10Hz
(0·001Hz below 1Hz on the 3Hz range).

Accuracy is ±1 digit to 2·1Hz (to 0·21Hz, Symmetry off, or to 0·42Hz,
Symmetry on, on the 3Hz range); below this the accuracy is ±1% of range
full scale (unspecified with Symmetry on).

Amplitude: Display shows peak-to-peak amplitude or rms value. Display corrected for

attenuator setting. 3-digit resolution, accuracy typically ± 5% of range full
scale.

DC Offset: 3-digit resolution; accuracy typically ± 2% setting ±1 digit.

Display corrected for attenuator setting.

, reducing to 1Vrms

External Frequency Measurement (TG330 & TG320)

Frequency Range: 5Hz to >20MHz and <20MHz to >120MHz in 2 switchable ranges.
Input Sensitivity: 50mVrms (sinewave).
Measurement Time: Selectable 0·5s or 5s.
Resolution: 6 digits in 0·5s; 7 digits in 5s.
Accuracy: ±1 digit ± timebase accuracy.
Timebase Accuracy: ±10ppm initial error; ± 5 ppm/year ageing rate; typically less than

0·5 ppm/ºC.

GENERAL

POWER REQUIREMENTS

AC Input Voltage: 220V AC-240V AC or 110V AC-120V AC ±10%, 50/60Hz, by internal

adjustment. Installation Category II.
Power Consumption: 25VA max.
Operating Range: + 5°C to + 40°C, 20% to 80% RH.
Storage Range: –10°C to + 65°C
Environmental: Indoor use at altitudes up to 2000m, Pollution Degree 2.
Size: 260(W) x 88(H) x 235(D)mm (10.2 x 3.4 x 9.2") excluding handle and feet.
Weight: 1.9kg (4.2lb).
Safety: Complies with EN61010-1.
EMC: Complies with EN61326.

5

EC Declaration of Conformity

We Thurlby Thandar Instruments Ltd
Glebe Road
Huntingdon
Cambridgeshire PE29 7DR
England

declare that the

TG315, TG320 and TG330 3MHz Function Generators

meet the intent of the EMC Directive 2004/108/EC and the Low Voltage Directive 2006/95/EC.
Compliance was demonstrated by conformance to the following specifications which have been
listed in the Official Journal of the European Communities.

EMC

Emissions: a) EN61326-1 (2006) Radiated, Class B

b) EN61326-1 (2006) Conducted, Class B
c) EN61326-1 (2006) Harmonics, referring to EN61000-3-2 (2006)

Immunity: EN61326-1 (2006) Immunity Table 1, referring to:

a) EN61000-4-2 (1995) Electrostatic Discharge
b) EN61000-4-3 (2006) Electromagnetic Field
c) EN61000-4-11 (2004) Voltage Interrupt
d) EN61000-4-4 (2004) Fast Transient
e) EN61000-4-5 (2006) Surge
f) EN61000-4-6 (2007) Conducted RF
Performance levels achieved are detailed in the user manual.

Safety
EN61010-1 Installation Category II, Pollution Degree 2.

6

CHRIS WILDING
TECHNICAL DIRECTOR

1 May 2009

This instrument has been designed to meet the requirements of the EMC Directive 2004/108/EC.
Compliance was demonstrated by meeting the test limits of the following standards:

Emissions

EN61326-1 (2006) EMC product standard for Electrical Equipment for Measurement, Control and
Laboratory Use. Test limits used were:

a) Radiated: Class B
b) Conducted: Class B
c) Harmonics: EN61000-3-2 (2006) Class A; the instrument is Class A by product category.

Immunity

EN61326-1 (2006) EMC product standard for Electrical Equipment for Measurement, Control and
Laboratory Use.

Test methods, limits and performance achieved are shown below (requirement shown in
brackets):

a) EN61000-4-2 (1995) Electrostatic Discharge : 4kV air, 4kV contact, Performance A (B).

EMC

b) EN61000-4-3 (2006) Electromagnetic Field:

c) EN61000-4-11 (2004) Voltage Interrupt: ½ cycle and 1 cycle, 0%: Performance A (B);

d) EN61000-4-4 (2004) Fast Transient, 1kV peak (AC line), 0·5kV peak (signal connections),
Performance A (B).

e) EN61000-4-5 (2006) Surge, 0·5kV (line to line), 1kV (line to ground), Performance A (B).
f) EN61000-4-6 (2007) Conducted RF, 3V, 80% AM at 1kHz (AC line only; signal

connections <3m, therefore not tested), Performance A (A).
According to EN61326-1 the definitions of performance criteria are:

Performance criterion A: ‘During test normal performance within the specification limits.’
Performance criterion B: ‘During test, temporary degradation, or loss of function or

performance which is self-recovering’.
Performance criterion C: ‘During test, temporary degradation, or loss of function or

performance which requires operator intervention or system reset occurs.’

Cautions

To ensure continued compliance with the EMC directive observe the following precautions:

3V/m, 80% AM at 1kHz, 80MHz – 1GHz: Performance A (A) and 1.4GHz to 2GHz:
Performance A (A); 1V/m, 2.0GHz to 2.7GHz: Performance A (A).

25 cycles, 70% and 250 cycles, 0%: Performance B (C).

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.

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

type, see the Service Manual.

7

Safety

This instrument is Safety Class I 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 instruction 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 2 environment in the
temperature range 5°C to 40°C, 20% - 80% RH (non-condensing). It may occasionally be
subjected to temperatures between +5°C and –10°C without degradation of its safety. Do not
operate while condensation is present.

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.

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.

Do not wet the instrument when cleaning it.
The following symbols are used on the instrument and in this manual:-

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

terminal connected to chassis ground.

8

alternating current.

Mains Operating Voltage

The operating voltage of the instrument is shown on the rear panel. Should it be necessary to
change the operating voltage from 230V to 115V or vice-versa, proceed as follows:

1. Disconnect the instrument from all voltage sources.

2. Unclip the front bezel by gently pulling the centre of each long edge up and forward.
The case halves are held together by 4 plastic push-rivets. Use the blade of a small

screwdriver in the slot beside each rivet to first ease out the rivet head and then fully
remove the rivet body. Separate the case halves. Visit www.tti-test.com
details.

3. Remove the 6 screws securing the main pcb to the case upper and lift the pcb free,
complete with front and rear panels.

4. Change the appropriate zero-ohm links beside the transformer on the pcb:

Link LK2 only for 230V operation
Link LK1 and LK3 only for 115V operation

5. Refit the pcb to the case upper, ensuring all connections (especially safety earth) are
remade as before, and refit the case lower.

Installation

for further

6. To comply with safety standard requirements the operating voltage marked on the rear

7. Change the fuse to suit the new operating voltage, see below.

Fuse

The correct time-lag fuse must be fitted for the selected operating voltage.
For 230V operation use 125mA (T) 250V HBC.
For 115V operation use 250mA (T) 250V HBC.
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 are prohibited.

Mains Lead

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

Brown - Mains live
Blue - Mains Neutral
Green/Yellow - Earth

panel must be changed to clearly show the new voltage setting.

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.

9

Switching On

Switch on the generator using the ON/OFF switch on the rear panel. To fully disconnect from the
AC supply unplug the mains cord from the back of the instrument or switch off at the AC supply
outlet; make sure that the means of disconnection is readily accessible. Disconnect from the AC
supply when not in use.

TG330/TG320: Ensure that the push-button switches in the SWEEP and AMPLITUDE
MODULATION/EXT COUNTER sections of the control panel are all set to the position,
i.e. set the generator to its normal, unmodulated, running mode. The display will show the
frequency and peak-to-peak output amplitude with appropriate range annunciators.

Frequency Setting

Frequency is set by pressing the appropriate FREQUENCY RANGE push button and rotating the
calibrated FREQUENCY vernier. The vernier controls provide a 1000:1 frequency change within
each range. The auto-ranging meter makes reciprocal frequency measurements down to 2·1Hz
(to 0·21Hz on the 3Hz range); the display update rate in this mode is 130ms or 1 waveform
period, whichever is the longer. Below these frequencies a fast measurement update rate is
maintained by changing the measurement method but accuracy is reduced, see Specification.

When SYMMETRY is switched ON the SYMMETRY control can be used to vary the duty cycle
from 1:10 to 10:1 to produce sawtooth and variable pulse-width waveforms. Optimum
performance of the SYMMETRY control is achieved on the top decade of each frequency range.
When SYMMETRY is selected SYM shows in the display and the generator frequency is divided
by 10; the display shows the correct frequency. The changeover in frequency measurement
method now happens at 0·21Hz on the 30Hz range and 0·42Hz on the 3Hz range.

Operation

Waveform

The output waveform shape is selected by depressing one of the three function buttons to give
sine, square or triangle. With all three switches out (accomplished by half-depressing any one)
the output will be a DC level only; this is useful as it permits input threshold testing of a circuit
without having to connect up an external DC supply.

Amplitude

The amplitude of the MAIN OUT outputs is set by the AMPLITUDE control and the ATTENUATOR
switches. Maximum output is 20 volts peak-to-peak open-circuit, 10 volts
peak-to-peak when terminated with the outputs characteristic impedance.

The AMPLITUDE control has greater than 20dB range; the ATTENUATOR switches permit
selection of up to -60dB attenuation (both switches pressed together). Used together these
controls provide a range of 20V peak-to-peak down to 2mV peak-to-peak, or 10V peak-to-peak
down to 1mV peak-to-peak into the output’s characteristic impedance.

Still greater attenuation of the 50Ω MAIN OUT can be achieved by using standard 50Ω BNC
attenuators. To maintain waveform integrity only 50Ω cable should be used and the receiving end
should be terminated with a 50Ω load.

The MAIN OUT outputs will withstand a short circuit for a period of 10 minutes at maximum output
and greater periods at lower output levels. However, damage will occur if an external voltage is
connected to the output sockets.

The 50Ω and 600Ω outputs are not independent; terminating one will affect the amplitude of the
other.

The amplitude is displayed on the right-hand side of the LCD; pressing the PK-PK/RMS button
beside the display will alternate the reading between peak-to-peak volts (Vp-p) and r.m.s. volts
(Vrms). The readout is correctly adjusted for attenuator setting and waveform shape.

The display shows open circuit voltage; the actual voltage at the socket will be half the displayed
value when the output is terminated with its characteristic impedance.

10

DC Offset

The DC OFFSET control has a range of ±10 volts from 50Ω/600Ω in all output modes; the control
has a centre detent for 0 volts. DC offset plus signal peak is limited to ±10V (±5V into the
characteristic output impedance); CLIP shows in the display when this limit is exceeded.
DC offset plus waveform is attenuated proportionally by the ATTENUATOR switches.

The DC offset can be displayed in place of the output amplitude by pressing the OFFSET button
beside the display. The display shows open circuit voltage offset; the actual voltage at the socket
will be half the displayed value when the output is terminated with its characteristic impedance.

Auxiliary Output

The AUX OUT output provides a fixed 0 to 5V TTL/CMOS pulse output at the same frequency,
symmetry and phase as the MAIN OUT outputs and is capable of driving 2 standard TTL loads.

Internal Sweep (TG330 only)

With INT SWEEP selected the output of the internal sweep generator is summed with the
FREQUENCY vernier. Select LIN or LOG sweep mode; the annunciators LIN-SWP or SWP-LOG
will show in the display accordingly.

Frequency Selection

Using the FREQUENCY RANGE switches select the lowest range within which the upper sweep
limit can be set; in this way the best setting resolution and the widest sweep range can be
realised.

Sweep Limits

Turn the STOP control to minimum (fully-anticlockwise). Hold the SET START button and set the
START (lowest) frequency on the display using the FREQUENCY vernier; the START frequency
must be set first. Now release the SET START button, hold in the SET STOP button and set the
STOP (highest) frequency on the display using the STOP control; release the SET STOP button.
Note that both the FREQUENCY vernier and the STOP control have a log characteristic when
LOG mode is selected.

The sweep limits can be checked at any time by depressing the SET START or SET STOP.

Sweep Rate

The generator sweeps both up and down at the speed set by the RATE control, i.e. it does not
reset rapidly after the upward sweep. This has the advantage that the suitability of the selected
sweep time can be continuously monitored.

Sweep Out

When INT SWEEP is selected the SWEEP IN/OUT socket becomes an output providing a 0V to
3V ramp from 600Ω impedance to drive the X-input of an oscilloscope or chart recorder.
Terminating this output with a resistor will reduce the output amplitude. Terminating with 600Ω will
halve the output giving 0V to 3V.

Holding in the SET STOP button holds the ramp at the maximum and can therefore be used to
set full scale on the oscilloscope or chart recorder.

Note that when SWEEP IN/OUT is used as an output to drive the X-input of an oscilloscope, the
oscilloscope should be set to DC coupling and not AC coupling which will cause a double image
at slow sweep speeds.

11

External Sweep

TG330: When EXT SWEEP is selected the SWEEP IN/OUT socket becomes an input.
TG320/TG315: The SWEEP IN socket is the external sweep control input.

The generator frequency can be swept, DC programmed or modulated by a suitable control
voltage applied to this input. The instrument sums the SWEEP IN voltage with the internal control
voltage derived from the FREQUENCY vernier to determine the operating frequency; the display
shows the resultant frequency.

A positive voltage increases the frequency; for frequency control with positive-going DC inputs the
vernier should therefore be set to the lower frequency limit of the range to be swept. For example,
a 0V to +3V signal will sweep the generator 3 decades up from range minimum, set by the
vernier, to range maximum.

Similarly, a negative voltage decreases the frequency and for negative-going DC inputs the
vernier should be set to the upper frequency limit of the range to be swept. For example, a 0V to ­3V signal will sweep the generator 3 decades down from range maximum, set by the vernier, to
range minimum.

To use a sweep signal which is symmetrical about ground, the vernier should be set to give a
frequency at approximately the centre of the band to be swept.

In external sweep mode the LIN/LOG selection is inoperative, i.e. the FREQUENCY vernier is
always operating linearly, as marked.

Note: Non-linear operation may result when the sweep input voltage is excessive; that is, when
the attempted generator frequency exceeds the range limits.

Amplitude Modulation (TG330 only)

Depressing the AM ON/OFF button selects AM. The depth of modulation can be adjusted over a
0% to 100% range using the modulation DEPTH control. When AM is selected the output
amplitude will drop to 50% at 0% modulation.

With the AM INT/EXT button in the INT (internal) position, the modulation source is an internal
400Hz sinewave oscillator. The INT-AM annunciator is displayed.

With the AM INT/EXT button in the EXT (external) position, and the EXT COUNTER ON/OFF
button in the OFF EXT AM position, external AM modulation is possible via the AM/COUNT IN
socket; the AM-EXT annunciator is displayed. The modulating signal applied should have no DC
offset or should be AC coupled. A 2V peak-to-peak signal gives approximately 100% modulation
with the modulation control at maximum. Modulating the generator with a squarewave gives step
changes in the output amplitude which are suitable for testing signal compressors and automatic
gain controlled circuits.

Applying a DC offset of approximately -1V gives suppressed carrier modulation. The DC offset
should first be adjusted to suppress the carrier, and the modulating signal then applied.

Applying a DC offset greater than -1V will invert the MAIN OUT outputs with respect to AUX OUT.
The generator can also be asynchronously gated on and off using the AM facility. Select EXT AM

and apply a suitably offset squarewave to the AM/COUNT IN input. The squarewave V
be approximately -1V to give carrier suppression and the V
normal full output.

should be +3V to +4V to give

high

low

should

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