Fluke 271 manual Effect of the output attenuator, Dc Offset Change * * By Output Level

Page 24

Effect of the output attenuator

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)

0.4V 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. Set the amplitude to 4 V p-p and the dc offset to +1.5 V.

Now change the amplitude by pressing AMPL, 0.4, V. The instrument will beep and you should see something like this for a few seconds:

**** WARNING 07 ****

* DC OFFSET CHANGE * * BY OUTPUT LEVEL *

********************

Then this:

PER =80.00000us

VhiZ=+4.00 Vpp 50Ω

DC=+1.50 V (+151.mV)

SYM=50.0% (50.0%)

The figure in brackets to the right of the programmed dc offset is the value which results from the application of 20 dB of attenuation. It may differ slightly from the calculated value (150 mV) because of the attenuator's saved calibration factors.

14

Image 24

Contents Getting Started Manual Programmable 10 MHz DDS Function GeneratorLIMITED WARRANTY AND LIMITATION OF LIABILITY To register your product online, visit register.fluke.comSafety Getting Started Manual Safety continued The following symbols are used on the instrument and in this manualTerminal connected to chassis ground Mains supply OFF Mains supply ON Alternating current Warning - hazardous voltages may be presentPage EMC Compliance EmissionsImmunity e EN61000-4-5 1995 Surge 0.5 kV line to line, 1 kV line to ground Table of Contents Titleviii AUX OUTGetting Started IntroductionBefore You Start Mains Supply VoltageExternally Applied Voltages Controls and Connections Getting StartedFigure 1. Model 271 Front Panel shx0001f.gifThe Liquid Crystal Display ControlsFunction Keys FIELD and DIGIT Keys and the Rotary Control Numeric, Units and SET Keys MODE Keys UTILITIES KeysOUTPUT Key RECALL and REMOTEFront Panel Inputs and Outputs EXT TRIGMAIN OUT AUX OUTRear Panel Connectors CLOCK IN/OUTVCA IN SYNC OUTRS232 and GPIB Interface Connectors TRIG/SWEEP OUTUsing the Instrument Plug in and switch on the instrumentStarting up Check the LCD DisplayGenerating Continuous Signals Set a frequency, for example 12.5 kHzFREQ=12.50000kHz VhiZ=+20.0 Vpp 50Ω DC=+0.00mV +0.00mV SYM=50.0% 50.0%Set the amplitude to +10 dBm Have a look at some other waveformsChange the dc offset =80.00000usEffect of the output attenuator DC OFFSET CHANGE * * BY OUTPUT LEVELPER =80.00000us VhiZ=+4.00 Vpp 50Ω DC=+1.50 V +151.mV SYM=50.0% 50.0% Adjusting the phase SOURCE=EXT TGEN=1.00ms 1.000kHz BURST COUNT= PHASE=+000 +000SOURCE=EXT TGEN=1.00ms 1.000kHz BURST COUNT= PHASE=+116 +116 Asymmetric waveformsGenerating Swept Signals TRIG/SWEEP OUT signalMODE=BEG-END LAW=LOG RAMP TIME=0.05 s TRIG SRC=CONTINUOUS MORE MODE=BEG-END LAW=LOG RAMP TIME=5.00 s TRIG SRC=CONTINUOUS MOREBEG FRQ=261.6000 Hz END FRQ=1.108700kHz MARK FRQ=523.3000 Hz MORE SOURCE=EXT TGEN=1.00ms 1.000kHz BURST COUNT=0001 PHASE=+000 +000 PHASE=+000 +000Generating a Triggered Burst FREQ=2.000000kHz VhiZ=+20.0 Vpp 50Ω DC=+0.00mV +0.00mVFSK Mode Special WaveformsStaircases FREQ A=800.0000 Hz FREQ B=1.200000kHz SOURCE=TGEN FREEFigure 2. 625-line PAL TV Signal step namestart µs amplitudeVALS=ABS AUTO=YES STEP=01 ACTIVE LENGTH=0256 LEVEL=+000 VALS=ABS AUTO=YES STEP=08 ACTIVE LENGTH=0005 LEVEL=+153Saving and Recalling Settings Arbitrary WaveformsRECALL ARB No SINX/X ENTER TO EXECUTE RECALL ARB No ARB 03 IS EMPTYOther Functions and Waveforms