185
Microphone Adjustments
Microphone Adjustments
An automatic gain control (AGC) limits the maximum amount of audio that may pass
through a console. If not properly adjusted, AGC circuits can amplify background noise
when the operator is not speaking. Proper adjustment and microphone practices will
eliminate background noise from transmitted audio.
To adjust the microphone levels
1. For a Model 4018, open the case to access the potentiometers. See Model 4018
. For Models 4116B, 4118, and 4217B, the
adjustments are accessible at the rear of the console.
to find the appropriate potentiometer for adjusting your microphone.
Table 80: Microphone Adjustments
3. While transmitting, speak into the microphone at a normal voice level and distance
from the microphone.
4. Turn the appropriate MIC potentiometer until the background noise is removed
without reducing voice amplitude.
5. Verify audio quality by monitoring the transmitted signal or by observing the level
meter under the time display. Optimum performance is achieved when the operator
speaks at the level and distance for which the console was adjusted.
6. If the PTT handset with cradle option was installed, the ear audio level is adjusted
by R7. This is set at the factory and probably needs no adjustment.
To perform precise microphone level adjustments
1. Begin transmitting a constant 1kHz alert tone from the console.
2. Adjust the console’s Alert Tone potentiometer to ½ turn past knee of compression
observable at the CIC mic test point.
3. Adjust the CIC mic for 0.25 Vrms (-10 dBm) at the mic test point.
4. Repeat steps 2 and 3 for each console.
Model
Level
Part
Label
4018
Handset/headset microphone
R68
E
Desktop microphone
R70
D
Gooseneck microphone
R69
GN
4116B, 4118, 4217B
Handset/headset microphone
–
H-MIC
Gooseneck/desktop microphone
–
D-MIC
Note
A desktop or gooseneck microphone connects to the D mic input of
the AUX AUDIO connector.
Summary of Contents for 4000 Series
Page 1: ...Series 4000 Communication Control System Installation and Configuration 025 9533Y...
Page 6: ...6 025 9533Y...
Page 28: ...Introduction 28 025 9533Y...
Page 88: ...Common Control Equipment Installation 88 025 9533Y Figure 22 Console Duplex Wall Jacks...
Page 110: ...Common Control Equipment Installation 110 025 9533Y...
Page 172: ...Console Installation 172 025 9533Y...
Page 192: ...Audio Level Adjustments 192 025 9533Y...
Page 230: ...Accessory Installation 230 025 9533Y...
Page 236: ...Console ANI Programming 236 025 9533Y...
Page 339: ...339 RSMP Operation Figure 99 Main Screen...
Page 350: ...Radio System Management Program 350 025 9533Y...
Page 362: ...Appendix B Troubleshooting 362 025 9533Y...
Page 418: ...Index 418 025 9533Y...