Axcera DT325B, Инструкция по эксплуатации, Страница: 55 / 65

350-Watt Digital VHF LB Transmitter Chapter 5, Detailed Alignment Procedures
DT325B, Rev. 0 5-5
5.5.3 Axciter Relay K2 Sample
Values
The K2 Relay is mounted on the Lower,
Right Side of the Cabinet, accessed
through the back. The RF Sample levels
must be measured with a power meter
before connecting them. Your
installation may require RF attenuators
to be placed in line with the samples to
get them within the desired range.
J1 Pre Filter connection to the FWD
power sample of the coupler before the
mask filter (Non-Linear Distortion).
Level into Relay at J1 should be 0 dBm
to –10 dBm. –5 dBm typical
J2 Post Filter connection to the forward
power sample after the mask filter
(Linear Distortion). The level into the K1
Relay at J2 should be 0 dBm to –10
dBm. –5 dBm typical, but must be
within .5 dB of the J1 sample.
5.5.4 Upconverter Down Converter
Adjustment
On the Axciter Modulator, activate the
Up/Downconverter Main screen by
selecting Up/Downconverter using the
button next to it on the right side of the
Axciter Main Screen. Activate the
Downconverter Output Gain by pushing
2 on the key board entry. Monitor the
DTVision Linear Display by pushing the
button next to the DTVision Linear
display on the right side of the Axciter
Main Screen. At the bottom of the
DTVision linear screen, locate the
reading next to RMS. If this reading is
between –10 dBm & 0 dBm no
adjustment is needed. If it is not, adjust
the “Downconverter Gain”, then view
the RMS value until it is within the –10
dBm to 0 dBm range.
5.6 System Calibration of Forward
and Reflected Powers Using the
Driver/AmplifierChassis
NOTE: Do not adjust R38 on (A4) the
Triple Peak Detector Board (1159713).
It is factory set for .7 to .8 VDC typical
AGC Reference to the VHF Amplifier Tray
and any readjustment may damage the
tray.
5.6.1 Forward Power Calibration
Check that transmitter is at 100%
output power, as shown on the LCD
display on the (A2) Driver/Amplifier in
the Set Up menus.
Measure with a VOM, TP31-14, Red, and
TP31-12, Black, at the terminal block
TP31 located on the rear chassis of the
(A2) Driver/Amplifier Chassis Assembly.
Adjust R14, Forward Calibration
Adjustment, on the (A4) Triple Peak
Detector Board, mounted on the lower
right side of the cabinet accessed
through the rear cabinet door, for a
reading of .8VDC on the VOM. Locate
the Forward Power Adjust screen on the
Driver/Amplifier LCD display in the Set
Up menus and adjust the up or down
arrow as needed to achieve 100%
output power. This completes the
forward power calibration.
5.6.2 Reflected Power Calibration
Switch the transmitter to Standby.
Remove the connector that is on Jack
J2, on the (A4) Triple Peak Detector
Board (1159713), and replace with the
connector now on J1, also inserting a 10
dB pad in series. Switch the transmitter
to operate. Monitor the LCD display on
the (A2) Driver/Amplifier in the Set Up
menus, reflected power screen. Adjust
R26, Reflected Calibration Adjustment,
on the (A4) Triple Peak Detector Board
for a reading of 10% on the display.
Switch the transmitter to Standby.
Move the connector back to J1 while
removing the 10 dB pad. Replace the
original connector onto J2. This
completes the reflected power
calibration.
This completes the set up and
adjustment of the DT325B transmitter.
If a problem occurred during alignment,
contact Axcera field service at 1-724-
873-8100.