ZETRON 640 DAPT XTRA, Installation And Repair Manual, Page: 107 / 210

Adjustment Procedures
025-9416 95
Note: Deviation levels that vary with frequency may indicate improper bandpass (pre-
emphasis) characteristics in the audio processing circuitry fed to the modulator.
Verify correct jumper settings
The TONE audio adjustment is complete.
Transmitter Digital Deviation Adjustment
RF deviation levels on binary digital transmissions are determined by your transmitter, not by the
station interface. Typically, digital paging involves modulating the RF carrier with a serial data
stream followed by audio messages. A digital “high” shifts the carrier frequency higher (f
c
+
f
dev
), while a digital “low” shifts the carrier lower in frequency (f
c
- f
dev
).
Follow the steps below to perform the DIGITAL deviation adjustment:
q 1. Call the digital pager defined in Figure 55.
q 2. Enter a long numeric display message (any numbers) after the Model 640 prompts.
The more digits entered, the easier this adjustment will be. We recommend entering
at least 20 DTMF digits.
q 3. Use the radio service monitor to measure the digital deviation of the transmission.
While the message is playing, adjust the transmitter for 4.5 - 5.0 kHz deviation.
The digital deviation adjustment is complete.
DIAL CLICK CARD LEVEL ADJUSTMENT
This procedure sets up the optional dial click decoder for the specific phone line. Refer to
Section 7 for details on field-installation of the dial click board. It is a good idea to readjust the
dial click card once in a while to ensure optimum digit decoding. Zetron recommends readjusting
the decoder 2 or 3 times a year.
Test Equipment
The following test equipment is required for the adjustment:
•
Touch-tone telephone
•
Rotary dial telephone
•
Phone cord “Y” connector for 2 telephones
•
Extender Card (Part No. 705-9431)
Note: The audio levels recognized by the dial click card depend only on the adjustment pots
(R6, R30). The FROM TEL pot on the trunk card has no effect on dial click decoding.
Follow the steps below to adjust the dial click levels:
q 1. Power-down the paging terminal.
q 2. Remove the top cover.