Console Installation
44
All the adjustments are accessible with the top cover in the raised position. See
on page 104 for the location of the microphone adjustments.
If the PTT handset with cradle option was installed, the ear audio level is adjusted by R7.
This would have been set at the factory and probably needs no adjustment.
Auxiliary Audio Input Adjustment
The console auxiliary audio input level adjustment is labeled “R63 AUX”. See
on page 104 for the location of the auxiliary input adjustment.
This input is not run through an AGC circuit and is not notch-filtered when transmitted
over tone-controlled channels; a third party notch filter can be used. The adjustment is best
performed while monitoring the deviation on the channel over which the auxiliary audio is
being transmitted. Fully compressed audio from the console will be at 0.75 Vrms (0 dBm,
2.2 V
PP
).
Speaker Minimum Audio Level
The Select and Unselect Speakers have adjustments to set the minimum audio level that
the front panel volume knobs may reduce the level to. These are set at the factory for no
audio output (completely counterclockwise) with the volume knobs completely off. The
minimum level can be set with the vertical mounted potentiometers next to the associated
speakers on the Display Board (Select speaker is R32 and Unselect is R1).
The other adjustments on the Display Board are set at the factory and should not require
adjustment. If the Display Board is replaced or repaired, the following adjustment is
required.
Warning!
Speaker DC bias is very sensitive. If adjusted incorrectly, the
speaker amplifiers can be damaged. Contact Zetron Technical
Support for assistance.
R21
Display contrast, adjusted for best viewing
R34
Select speaker DC bias, adjusted for minimum DC
voltage across select speaker (0
±
30 mV)
R7
Unselect speaker DC bias, adjusted for minimum DC
voltage across unselect speaker (0
±
30 mV)
STOP