Operating instructions

ACCEPTANCE TESTING
5-16 46882-311D
LF generator
C2590
DVM
AF INPUT
VOLTMETER
INPUT
TERMINALS
50Ω
UUT
Fig. 5-12 Audio frequency meter check
Audio voltmeter
Specification
Level accuracy: ±3% ±3 mV ± resolution 20 Hz to 50 kHz (DC and 20 Hz to 50 kHz
when DC coupled)
Resolution: 1 mV or 1% of reading.
Test equipment
Description Minimum specification Example
LF generator 50 Hz to 50 kHz 30 mV to 5 V RMS. IFR 2965
DC power supply 0 to 50 V
DVM DC measurement and AC measurement 20 Hz to
50 kHz.
Solatron 7150+
(1) Refer to Results table 5-26 on page 5-40. Connect the equipment as shown in Fig. 5-13,
connecting the LF generator output to the UUT AF input and via a T-piece to a DVM.
(2) Set the UUT to [AF TEST] press [AF Filter], [50 kHz LP] to set the Audio Input filter to
50 kHz Low-pass. Press AC/DC coupling until AC coupled is displayed.
(3) Set the DVM to measure Volts AC and the LF generator to frequency 1 kHz , level 30 mV
RMS (adjust until the DVM indicates as close to 30 mV as possible). Check that the level
indicated on the UUT voltmeter is within
±
3%
±
3 mV
±
resolution of the level indicated on
the DVM.
(4) Repeat step 3 with LF generator levels of 200 mV, 0.4 V, 0.8 V, 2 V, 4.5 V.
(5) This step is a functional check only and confirms that the audio filters switch in correctly with
minimal insertion loss. Set the UUT AF filter to 15 kHz LP and check that the UUT
voltmeter indicates within
±
6%
±
3 mV
±
resolution of the level measured with the 50 kHz
LP. Repeat with the 0.3 to 3.4 kHz band-pass filter. Set the LF generator to 100 Hz and set
the UUT filter back to 50 kHz LP. Note the reading and then set the UUT filter to 300 Hz
LP. Check that the UUT voltmeter indicates within
±
6%
±
3 mV
±
resolution of the level
measured with the 50 kHz LP.