User's Manual

Innovator CU250ATD, 250 Watt Transmitter System Alignment
Instruction Manual, Rev. 0 21
System Alignment
This transmitter was aligned at the factory and should not require additional
adjustments to achieve normal operation.
This transmitter is of a tray design with multiple boards inside the tray. If a board fails,
that board needs to be changed out with a replacement board. The failed board can then
be sent back to Axcera for repair. Contact Axcera Customer Service Department at 724-
873-8100 or fax to 724-873-8105, before sending in any board or module.
Set Up of the Output Power of the Transmitter
Check that the Auto/Man switch S1 on the IF Pre-Corrector Board is in the Automatic ALC
position. This is the normal operating position for the switch. The voltage at TP1 on the
IF Pre-Corrector Board should be .8 VDC with 100% output power.
Check that the Auto/Man switch S1 on the ALC Board is in the Automatic ALC position.
Adjust R75 the ALC pot on the ALC Board as needed to attain 100% output power. Switch
to Manual Gain (Manual ALC) and adjust the Manual Gain pot R62 for 100 % output
power. Switch the ALC Board back to Automatic ALC.
ALC Board Set-Up In the Tray
On (A5) the ALC Board (1308570), preset the Overdrive Threshold pot R38 full CW and
set R62, Manual Adjust, and R75, ALC Adjust, full CCW.
Apply an 8-VSB signal at -3 dBm average level to the J1 input jack to the tray. Switch
S1 to Manual Gain, and increase the output power to 100%. Calibrate the transmitter
output power using R23, Forward Calibration pot, on the Output Detector Board.
Turn the output power down to 10% power. Remove the output RF connector from J2
on tray and calibrate the reflected power to 10%, using R7, the Reflected Calibration
pot, on the Output Detector Board. Re-connect the RF output connector to the tray and
increase the power, in Manual gain, to 110%. Adjust the Overdrive pot R38, CCW until
the overdrive threshold just trips and the Overdrive Fault LED DS4 lights. Turn the pot
slightly CW so that power comes back up and DS4 goes out.
Switch S1 to ALC. Turn the ALC Adjust pot R75 until the power is 100%. Switch S1
between ALC and Manual to verify smooth switching, with minimal change in power.
Switch the tray Off and insert a 10 dB attenuator at the input. Switch the tray On and
verify the input fault LED comes on and the RF power Mutes. Output power should drop
by at least 20-30 dB.
Switch the tray Off and remove the 10 dB attenuator. Replace the input connector and
turn the tray back on. With the tray in ALC, use the ALC Adjust pot, R75, to decrease
the power to 10%. Remove the RF output connector from the tray. Verify that the
VSWR Cutback LED, DS6, comes on and the Reflected Power drops to approximately
6%. Reconnect the RF output connector and increase the power back up to 100%.
This completes the set up of the ALC board.