sunair RT-9000C, Operation And Maintenance Manual

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RT-9000C Hardware Supplement
Document No. 8121000602
Revision A (19 Mar 2007)
8-27
RT-9000 C
8.3.2.3 Alignment and Adjustment
8.3.2.3.1 Receive and Transmit Audio Level Adjustments
This procedure describes how to set the Receive Audio Output and Transmit Audio Input levels. All
adjustments, except for the Microphone Audio adjustment, can be performed with the equipment in receive-
state. These adjustments will normally not be necessary unless one of the following is true: 1.) Operation
using audio levels other than the factory settings is required. 2.) There is reason to believe that the factory
settings have been disturbed. Merely replacing the Digital Audio Assembly should not require readjustment.
All adjustments are performed on the Digital Audio 1A2A3 Assembly. Refer to Figure 8.10 to locate the
applicable adjustment points.
Preliminary
1. If the RT-9000C was powered-up, power it down now.
2. Observe proper Electrostatic Discharge damage prevention practices during this entire
procedure.
3. Remove the RT-9000C top cover. Refer to Section 5.2.1 in the RT-9000 Operation and
Maintenance manual.
4. Remove card cage top cover. Refer to Figure 5.4.1.3. This cover extends the full width of the RT-
9000C and is closest to the front panel.
Note: The RT-9000C uses loose hardware. When removing the card cage
cover fasteners, account for any lost hardware items to prevent
accidental short circuits later.
5. Unplug the small 6-pin connector entering the internal Power Supply enclosure. This
connector is about 2 inches behind the internal circulating fan. To unplug, squeeze the top tab
on the connector shell and pull the connector out from its chassis-mounted mate.
Note: This step temporarily disables the RT-9000C Transmitter Power
Amplifier. This prevents probable damage to the RF Signal Generator if
the transmitter is accidentally keyed while performing receive-state
adjustments.
6. Power up the RT-9000C.
7. Locate all Receive Audio adjustment points. Refer to Figure 8.10.
Receive Audio Output Adjustment
8. Set the RT-9000C as follows; Frequency: 8.000 MHz, Mode: ISB, AGC: Slow
9. Connect a 50-Ohm RF signal generator to RT-9000C ANT connector J4. Adjust the generator
output as follows; Frequency: 8.001 MHz, Output level: -70 dBm (70.7
µ
V), Modulation: none
.
10. Connect a 600-Ohm load resistor (non-inductive) to RT-9000C Receive Audio USB Output at
rear-panel AUDIO connector J5, pins L and M. Connect an audio voltmeter to monitor the
voltage across the load resistor.
11. Adjust potentiometer 1A2A3 R84 (USB RX) until the audio voltmeter indicates the desired
reading. The factory setting is 0 dBm.
12. Disconnect the load resistor and voltmeter and re-connect them to RT-9000C Receive Audio
LSB Output at rear-panel AUDIO connector J5, pins A and C.