® 271 Programmable 10 MHz DDS Function Generator Getting Started Manual PN 2423297 January 2005 © 2005 Fluke Corporation, All rights reserved. Printed in USA All product names are trademarks of their respective companies.
LIMITED WARRANTY AND LIMITATION OF LIABILITY Each Fluke product is warranted to be free from defects in material and workmanship under normal use and service. The warranty period is one year and begins on the date of shipment. Parts, product repairs, and services are warranted for 90 days.
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.
271 Getting Started Manual • 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. • Make sure that only fuses with the required rated current and of the specified type are used for replacement.
Safety (continued) 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. Mains supply OFF. Mains supply ON. Alternating current. Warning - hazardous voltages may be present.
EMC Compliance This instrument meets the requirements of the EMC Directive 89/336/EEC. Compliance was demonstrated by meeting the test limits of the following standards: Emissions EN61326 (1998) 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 (2000) Class A The instrument is Class A by product category.
271 Getting Started Manual e) EN61000-4-5 (1995) Surge: 0.5 kV (line to line), 1 kV (line to ground) Performance A. f) EN61000-4-6 (1996) Conducted RF: 3 V, 80 % AM at 1kHz (ac line only; signal connections <3 m not tested) Performance A. According to EN61326 the definitions of performance criteria are: Performance criterion A: ‘During test normal performance within the specification limits.
Table of Contents Title Introduction .................................................................................................................... Before You Start............................................................................................................. Mains Supply Voltage................................................................................................ Externally Applied Voltages ......................................................................................
271 Getting Started Manual AUX OUT ............................................................................................................. EXT TRIG............................................................................................................. Rear Panel Connectors............................................................................................. CLOCK IN/OUT.................................................................................................... VCA IN ..............
Getting Started Introduction Before You Start This Getting Started Manual for the model 271 Programmable 10 MHz DDS Function Generator is designed to provide an initial understanding of the way the instrument is operated. The manual is set out in the form of a tutorial, guiding you through a series of basic front panel operations in order to familiarize you with the controls and the modes of operation.
271 Getting Started Manual Externally Applied Voltages Caution - Front Panel Sockets To avoid risk of damage to the instrument: Do not apply external voltages to the MAIN OUT or AUX OUT sockets. Do not apply external voltages exceeding ±10 V to the TRIG IN socket. Caution - Rear Panel Sockets To avoid risk of damage to the instrument: Do not apply external voltages to the SYNC OUT or TRIG/SWEEP OUT sockets. Do not apply external voltages exceeding ±10 V to the VCA IN socket.
Getting Started Controls and Connections Controls and Connections shx0001f.gif Figure 1.
271 Getting Started Manual The Liquid Crystal Display Controls The 4-line x 20-character LCD panel is used to display and edit all the parameter values. The paradigm used for selecting fields and editing values is described below. Function Keys If necessary (because of temperature variations etc.), you can adjust the display contrast using a small screwdriver or trimmer tool inserted in the hole marked LCD.
Getting Started Controls and Connections Thus, for example, if you select kHz with the FIELD key, successive presses of the right DIGIT key (or rotating the knob clockwise) change the value and the units as follows: FIELD and DIGIT Keys and the Rotary Control The FIELD keys move the display cursor between fields. The fields in the display shown in figure 1 above are "FREQ=", "10.00000", "kHz", "VhiZ=" and so on. shx0004f.
271 Getting Started Manual In addition, if the display is of any menu other than the main menu, the ESCAPE key will return you to the main menu. Numeric, Units and SET Keys You can use these keys to enter parameter values directly. For example, to set the period to 125 µs, select the first field (FREQ), change it to period (PER) by pressing a DIGIT key, then enter 1, 2, 5, us on the keypad. shx0009f.
Getting Started Controls and Connections MODE Keys UTILITIES Keys Alternate presses of a MODE key will turn the mode (TRIG, GATE, AM, etc.) on or off, and when the function is on the associated lamp is lit. The UTILITIES keys give access to the STORE, RECALL and REMOTE edit menus. The instrument can store up to nine set-ups (numbered 1 to 9), and can recall any of those plus set-up 0 which is the factory default set-up and is not editable.
271 Getting Started Manual Front Panel Inputs and Outputs EXT TRIG MAIN OUT EXT TRIG is the external trigger input for the noncontinuous modes (trigger, gate, sweep, FSK and hop) and for synchronizing the generator as a slave to an external master generator. MAIN OUT is the 50 Ω or 600 Ω output from the main generator. It will provide up to 20 V p-p into a highimpedance load or 10 V p-p into a matched 50 Ω or 600 Ω load. It can tolerate a short circuit for 60 seconds. shx0005f.
Getting Started Controls and Connections Rear Panel Connectors VCA IN CLOCK IN/OUT This is the modulation input for voltage controlled amplitude (VCA). +2.5 V will drive the amplitude to 100 % of its programmed value. The input impedance is approximately 6 kΩ. This socket operates both as an input and as an output, depending on the mode in which the instrument is being used. shx0013f.
271 Getting Started Manual TRIG/SWEEP OUT RS232 and GPIB Interface Connectors The TRIG/SWEEP output socket provides both trigger and marker signals, depending on the instrument's mode of operation. These sockets are for controlling the instrument remotely, using a PC or other controller device. Remote control is beyond the scope of this Getting Started Manual, but is covered in detail in chapter 16 of the Users Manual. shx0016f.
Getting Started Using the Instrument Using the Instrument Starting up While familiarizing yourself with the instrument you will find it useful to observe the outputs on an oscilloscope. For most purposes it is sufficient to connect the MAIN OUT front panel socket to the oscilloscope's Y input, and the AUX OUT front panel socket to the oscilloscope's trigger input. The ac supply on/off switch is located at the bottom left side of the front panel.
271 Getting Started Manual Generating Continuous Signals Select SINE on the function keys, if it is not already selected. If there is no signal at the oscilloscope input it will almost certainly be because the generator's output is switched off. If the lamp next to the MAIN OUT socket is not lit, press the OUTPUT key. The AUX OUT socket is always on. Press the right FIELD key to put the cursor in the numeric part of the top line and move the cursor a couple of digits to the right with the right DIGIT key.
Getting Started Using the Instrument Set the amplitude to +10 dBm Have a look at some other waveforms You can do this by keying AMPL, 1, 0, dBm. Using the function keys you can select any of the waveforms and observe them on the oscilloscope display. The display will now look like this: Change the dc offset PER =80.00000us OUT =+10.0dBm 50Ω DC=+0.00mV (+0.00mV) SYM=50.0% (50.0%) If you switch the amplitude display back to VhiZ you should see: PER =80.00000us 50Ω VhiZ=+4.00 Vpp DC=+0.00mV (+0.
271 Getting Started Manual Effect of the output attenuator The instrument has an output attenuator with fixed steps of 20 dB. The attenuator follows the output stages so any dc offset added to the waveform is subject to the attenuator. With the waveform amplitude set to 4 V p-p the attenuator is switched out; however if you adjust the output to (say) 0.4 V p-p, 20 dB of attenuation is switched in. When this happens you will be warned that the dc offset has been changed. Try it.
Getting Started Using the Instrument Asymmetric waveforms Symmetry adjustments work in much the same way as dc offset adjustments. However, because of the lengthy calculations which the instrument makes following a change to the symmetry setting, you may find it easier to use direct numeric entry rather than the rotary control. Again, the symmetry of the output is displayed in brackets at the right of the programmed value and in certain circumstances the programmed and actual values may differ.
271 Getting Started Manual instrument's AUX OUT socket in order to see the phase effects more clearly. There are some limitations on using the phase control at frequencies above 30 kHz - chapter 5 of the Users Manual explains these in detail. Generating Swept Signals The instrument has an independently-controlled internal trigger generator which produces a square wave with a period from 20 µs to 200 s (in 20 µs steps), corresponding to a repetition frequency from 0.005 Hz to 50 kHz.
Getting Started Using the Instrument At this point the lamp next to the SWEEP key should be flashing and the display should look like this: MODE=BEG-END LAW=LOG RAMP TIME=0.05 s TRIG SRC=CONTINUOUS MORE->>> All these settings are fine except for the sweep time, which is too short if you are listening to the signal. Change the sweep time to, say, 5 seconds. When you press the ENTER key the display will return to the main menu, so press EDIT and SWEEP again and use the FIELD key to move to the next screen.
271 Getting Started Manual Generating a Triggered Burst In this exercise you will use the internal trigger generator to initiate a burst of 500 cycles of a 2 kHz tone twice every second. The period of the internal trigger generator is thus 500 ms. Press RECALL, 0, ENTER to reset to the factory defaults. Then press EDIT and TRIG. The lamp next to the TRIG key should flash and the display should show: SOURCE=EXT TGEN=1.00ms 1.
Getting Started Using the Instrument FSK Mode Special Waveforms The FSK (frequency shift keying) mode can also be driven from the internal trigger generator. Setting up is very straightforward; the following settings give a continuous waveform which switches between 800 Hz and 1.2 kHz twice every second. Staircases The edit menu for the FSK mode includes the basic settings for the trigger generator, so there is no need to visit the trigger generator set-up screen itself.
271 Getting Started Manual set the levels to produce five monochrome stripes from left to right: grey, white, grey, black and grey again. Our line signal thus looks like the drawing below: shx0019f.gif Figure 2. 625-line PAL TV Signal In the instrument the number of horizontal points which make up the complete waveform is 1024, so the horizontal steps must be scaled to the range 0-1023.
Getting Started Using the Instrument step name 0 amplitude start scaled to 0-1024 step length amplitude scaled to 0-511 0 30% 0 29 153 start (µs) 1 sync pulse 1.8 0% 29 75 0 2 back porch 6.5 30% 104 90 153 3 50% grey 12.1 65% 194 165 332 4 white 22.4 100% 358 165 511 5 50% grey 32.8 65% 525 165 332 6 black 43.1 30% 690 165 153 7 50% grey 53.4 65% 854 165 332 8 front porch 63.
271 Getting Started Manual The second screen appears: VALS=ABS AUTO=YES STEP=01 ACTIVE LENGTH=0256 LEVEL=+000 Continue entering the pairs of length and level values in the table until the last step (08). This is the final screen in which the length and level have been keyed in, immediately before the final press of the ENTER key: VALS=ABS AUTO=YES STEP=08 ACTIVE LENGTH=0005 LEVEL=+153 The remaining steps (9 to 15 inclusive) are all inactive. Press ESCAPE to complete this part of the set-up.
Getting Started Using the Instrument Saving and Recalling Settings Arbitrary Waveforms Having done all this work it would be wise to save the settings for future use. You can do this simply by pressing the STORE key, followed by a number in the range 1 to 9 and the ENTER key. Store 0 is reserved for the factory default settings. You can recall the set-up at any time using the RECALL key. Arbitrary waveforms are best defined on a PC and downloaded to the instrument via the RS232 or GPIB interface.
271 Getting Started Manual arbitrary waveforms 01 to 05. These first five store locations are available for waveforms downloaded from a PC. When you press the ENTER key the output switches to the selected waveform but the display does not change; press ESCAPE to return to the main menu, then press ARB and switch the output on to initiate the signal. Note that there are no facilities for storing waveforms edited using the instrument itself.
