Microwave Data Systems MDS 4310, Installation, Operation & Field Maintenance

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4-14 FIELD TESTS & ADJUSTMENTS MDS 05-2415A01, Rev. A
Putting Things Back Together
1. Restore the transceiver’s time-out timer to the original value (if changed) using the
PTOT_XXX
command on the HHT. The factory default setting is 180 seconds.
2. Reinstall the cover. Reconnect the antenna feedline and reconnect the RTU’s
interface cables to the transceiver.
3. Confirm that the unit operates normally with the associated RTU.
4. Secure all cables, providing strain relief if necessary, and check connectors for
tightness.
This completes the set-up of the transceiver with a 1200 baud modem installed. For
additional information on the 1200 baud modem refer to Appendix A.
TEST PROCEDURE
➍
:
TRANSMIT FREQUENCY, SQUELCH, DEVIATION,
AND RECEIVE AUDIO OUTPUT—For Radios with MDS’s Internal 4800 BPS Modem
In the following procedures, references to SW1 & SW2 relate to the switches of the Data
Terminal Emulator (Figure 4-2). See Figure 4-5 for an assembly drawing of the 4800 baud
Modem. See Figure 4-9 for the locations of adjustable controls on the transceiver
motherboard.
Set-up
1. Remove the cover from the transceiver by loosening the four captive cover screws
and lifting it straight up. Make a list of the settings of configuration switch S1 on the
modem—they will be changed temporarily during the alignment procedure.
2. Close the Diagnostics Channel and disconnect the HHT.
3. Connect the Data Terminal Emulator to the
INTERFACE
connector.
4. Connect the transceiver’s
ANTENNA
connector to the input of the service monitor
using a short length of RG-8/U or RG-214 coaxial cable. Set up the service monitor
to monitor the transmitter’s center (channel) frequency.
5. Set the transmitter deviation to minimum by rotating R168, Deviation, fully counter
clockwise.
6. On the modem, set S1 to positions 2 and 4 ON (Closed), all others OFF (Open).
Transmit Frequency
1. Key the transmitter by raising RTS (SW1 Closed). The TXD line should be at logic
low (LED annunciator TD [TXD] off).
2. Check for correct transmit center frequency. With TXD low (SW2 Open) the
transmitted frequency should be within 100 Hz of the assigned center frequency. If
necessary, adjust the TX Frequency Adjustment control on the TCXO.
R
M
If Remote Maintenance is installed, use the
IF / DF / INCF / DECF
commands
instead of the adjustment on the TCXO. The
IF / DF
commands
increment/decrement the frequency in single steps while the
INCF / DECF
commands make larger jumps by adding a space and a number to the
command. (For example:
INCF_8
to increase the frequency by eight steps out
of 100.) When finished, type
RMST
to store the setting.