ZETRON 640 DAPT XTRA, Руководство по установке и ремонту

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Adjustment Procedures
025-9416 85
ADJUSTMENT PROCEDURES
OVERVIEW
The following procedures describe the level adjustments necessary to make the Model 640
operate properly. Each procedure should be performed following the initial installation process
and whenever the hardware configuration changes. For example, if the telephone line signaling
format changes, or if new options are purchased, the appropriate levels should be readjusted.
In addition to adjusting the paging terminal interfaces when hardware changes, some adjustments
should be performed as part of regular maintenance.
Measurement Conventions
The following conventions are used in each of the adjustment procedures.
All trunk level readings are expressed in decibels (dB) and AC volts RMS (Vrms). All dB read-
ings have been determined using a bridging (high impedance) AC voltmeter calibrated in deci-
bels referenced to 1 milliwatt dissipated into a 600 ohm load (dBm). All voltage readings have
been obtained using an AC true-RMS voltmeter measuring sinusoidal waveforms.
Note: The measurements are NOT made in dBm because the line termination may not
necessarily be 600 ohm.
WARNING: Field technicians must be sure lines are connected (terminated) properly before
setting adjustments.
If assistance is needed to complete any of the adjustments, contact Zetron technical support.
TRUNK CARD LEVELS
The following procedures apply to both types of trunk cards (standard and 4-wire audio dual
trunk interface).
Each telephone interface line requires three separate adjustments:
•
audio level from the telco (labeled FROM TEL)
•
telco line balance R (labeled BAL R)
•
telco line balance C (labeled BAL C)
These potentiometers have been set at the factory, but usually need to be field-adjusted to match
actual phone line characteristics.
The voice audio on each telephone interface line has a gain control, which automatically
compensates for differences in caller loudness and call-to-call gain changes. The AGC KILL
switch is used in conjunction with the three pots to make accurate adjustments.