load
8
100
900
Dummy
load
Power
Amplifier
Divide
by 10
100W
LA102 AUDIO MEASURING SET
LA102 Measuring Set
(configuration W2 set)
100W
Fig. 2.22 Using an 8 Dummy Load and Attenuator for Power Measurement
2.23 Printing the Displayed Values Printing displayed values in manual mode Printing
The LA102 can print the measured frequency, level and phase which are displayed on the
LCD. Press
, and a single line will be printed, for example:
Level 1 2-100kHz RMS L 0.01dB 1001.6Hz 0d
This facility should be useful when testing equipment manually where results are
normally written down by hand. It is possible to print results for any measurement, so a
simple test sheet showing level, noise, crosstalk, distortion, W&F and speed can be
produced very easily. A printer must be connected and set up correctly (see chapter 8),
otherwise a
NO HANDSHAKE message will be displayed. For more sophisticated results
printouts sequence mode should be used (see chapter 3).
2.24 Output Waveform Output waveform Mute
The LA101 generates a sine wave output by default (indicated by SIN), because this is
most useful for audio testing. Pressing
will toggle between sine and square
waves, while pressing
will cycle through DOUBLE, DC0, DC+, DC-, TRI, SAW+
and SAW- waveforms (fig. 2.23). Pressing
after will restore sine waves,
and another
will select the last waveform which was selected with (this allows
quick switching between sine and double tone waveforms, for example).
DC0 is for noise test purposes; the internal oscillator is stopped and the input to its digital
to analogue converter (DAC) is set to zero. This is different from MUTE because most of
the LA101 circuits are still connected to the output, and the noise level is therefore higher.
It is used automatically before tone bursts so that the signal can be turned on very quickly
at a zero-crossing, without any glitches caused by relay switching.
DC+ and DC- generate positive and negative DC voltages at the displayed level (ie the
same voltage as a positive or negative square wave half-cycle). Square waves are
33
2. Manual Operation
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