Operating instructions

OPERATING MANUAL 2945A
46882-311D 5-19
AF distortion & SINAD meter
Specification
Frequency range: 1 kHz.
Distortion meter accuracy ±5% of reading ± 0.5% distortion.
SINAD meter accuracy ± 1 dB.
(1) Refer to Results table 5-29 on page 5-41. Connect UUT AF INPUT to UUT AF GEN OUT.
(2) Set the UUT to [AF TEST], [Audio Gen], [LEVEL] 1 V. Press [Gen 1/Gen2] to select AF
Gen 2, then [FREQ] 400 Hz, [LEVEL] 20 mV, [ON]. This should cause AF Gen 1 to be set
to 1 kHz, 1 V, and AF Gen 2 to 400 Hz, 20 mV. If these values are not set, make the
required adjustments to achieve them.
(3) Press [Return], [DIST/S-N], [DIST’N] to switch the UUT distortion meter on.
(4) Check that the distortion meter reads between 1.4 and 2.6% distortion, i.e. 2% distortion
±
5%
of reading
±
0.5% distortion.
(5) Set AF Gen 2 level to 250 mV.
(6) Select AF Gen 1 level and adjust until the UUT voltmeter reads 1.00 V.
(7) Check that the distortion meter reads between 23.2 and 26.8% distortion, i.e. 25% distortion
±
5% of reading
±
0.5% distortion.
(8) Press [Return], [DIST/S-N], [Sinad] to switch the UUT SINAD meter on.
(9) Check that the SINAD meter reads 12 dB
±
1 dB.
RF input tests
Modulation analyzer - FM
Specification
Frequency range: 100 kHz to 1.05 GHz.
Modulation frequency range: 10 Hz to 15 kHz.
Deviation range: 0 to 75 kHz.
Resolution: 10 Hz below 2 kHz deviation
1% above 2 kHz deviation
Accuracy (see Note 1) ±5% ± resolution at 1 kHz modulation frequency.
±7.5% ± resolution for modulation frequencies from 50 Hz to 10 kHz.
Demodulation distortion Less than 2% at 1 kHz and 5 kHz FM,
Demodulation scope
accuracy
±10%
Demodulation output socket 200 mV peak to peak ± 10% per 1 kHz deviation
Demodulation filters 300 Hz LP, 300 Hz HP, 3 kHz LP, 0.3 to 3.4 kHz BP, 15 kHz LP,
50 kHz LP, 750
µs de-emphasis
Residual FM: Less than 30 Hz (300 Hz to 3.4 kHz)
Note 1:
At low modulation levels, the residual AM/FM may become significant.