Operating instructions

ACCEPTANCE TESTING
5-14 46882-311D
Audio generator distortion
Specification
Distortion: Less than 0.5% at 1 kHz.
Less than 1% from 50 Hz to 15 kHz .
Test equipment
Description Minimum specification Example
Distortion
analyzer
Capable of measuring distortion from 1 kHz to
15 kHz down to 0.1%.
IFR 2965 or
HP8903B
C2589
AF GEN
OUTPUT
AF
INPUT
UUT
Distortion analyzer
Fig. 5-11 Audio generator signal purity checks
(1) Refer to Results table 5-21 on page 5-38. Connect the UUT AF GEN output to the AF input
of the distortion meter, as shown in Fig. 5-11.
(2) Set the UUT to [AF TEST], [Audio Gen], [FREQ] 1 kHz, [LEVEL] 4 V. Audio Gen 1
should be set to sinewave and Audio Gen 2 should be OFF.
(3) Set the Distortion meter to measure distortion at 1 kHz in a 0.3 to 3.4 kHz bandwidth..
(4) Check that the distortion indicated is less than 0.5%.
(5) Repeat step (4) with AF Gen 1 level set to 100 mV.
(6) Set the Distortion meter to measure distortion in a 20 kHz Low-pass bandwidth.
(7) Set AF Gen 1 to provide 4 V at a frequency of 2 kHz. Check that the distortion indicated on
the Distortion meter is less than 1%. (If a 2965 is being used, see the Operating Manual for
instructions on setting distortion measurement to different frequencies.) Repeat at 5 kHz. Set
the low-pass bandwidth on the distortion meter to NONE and repeat with AF Gen 1 set to
provide 15 kHz.
(8) Refer to Results table 5-22 on page 5-38. Repeat the above procedure, except this time with
AF Gen 1 switched OFF and AF Gen 2 ON.
Audio generator frequency
This is a functional check only. The Audio generator frequency is derived digitally and provided
that the hardware is operational its accuracy will be maintained. The instrument’s internal
reference frequency is checked elsewhere. This check is listed at this point as it is one of the AF
generator tests, but it should be carried out after the UUT audio frequency meter has been checked
(see AF input tests; AF frequency meter).