Tait T855 - De-Emphasised Audio Frequency Response

M850-00 T855 Functional Testing B4.5
Copyright TEL 31/09/98
4.6 De-emphasised Audio Frequency Response
Set RV210 (front panel line level) to provide 0dBm output at 1kHz modulating fre-
quency.
Sweep the modulating frequency, checking that the line audio response closely
follows that shown in Figure 4.1 - the limits should not be exceeded.
Figure 4.1 T855 De-emphasised Audio Frequency Response
Wide Bandwidth
Narrow Bandwidth
+25
+20
Audio Level (dB ref. to O/P @ 1kHz)
+15
+10
+5
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
100 200 300 500 1k 2k 3k 5k 10k
Frequency (Hz)
25°C 13.8V
Ref. audio power:
+0.0dBm @ 1kHz
+25
+20
Audio Level (dB ref. to O/P @ 1kHz)
+15
+10
+5
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
100 200 300 500 1k 2k 3k 5k 10k
Frequency (Hz)
25°C 13.8V
Ref. audio power:
-2.2dBm @ 1kHz
Mid Bandwidth
+25
+20
Audio Level (dB ref. to O/P @ 1kHz)
+15
+10
+5
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
100 200 300 500 1k 2k 3k 5k 10k
Frequency (Hz)
25°C 13.8V
Ref. audio power:
-2.5dBm @ 1kHz