ASL INTERCOM PS 6379 MK2 User Manual page 11

Null Adjustment procedure, for each channel separately:
• turn the 'Own Voice" (side tone) control knob to minimum
• set Null Adjust trimmers in start position: fully clockwise.
• switch off the microphones of all connected (speaker-) stations
• make sure that there is no automatic speaker attenuation (turn trimmer #21 fully
clockwise)
• push the TALK button of the channel to be null adjusted
• slowly turn up the listen volume of the PS 6379 Mk2 (channel + master volume)
• speak into the gooseneck microphone
• adjust the speaker listen level to a minimum by turning the null adjust trimmers
counter clockwise (first the LOW trimmer and then the HIGH trimmer; repeat this a
few times)
• Connect a headset (the loudspeaker and gooseneck mic are now automatically dis-
abled) and speak into the headset microphone. Check whether the level of your
voice in the headset can(s) is sufficient. If not, push this level up by turning the
OWN VOICE knob ( #4) clockwise.
The operating area of the Null Adjust trimmers is between fully clock-wise and minimum
level.
Should the number of user stations on a channel and/or the length of the party line ca-
ble change, the null for that channel has to be adjusted again.
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