Data Sheet Chapter 4

3-kW UHF Transmitter Chapter 4, Detailed Alignment Procedures
835-3, Rev. 0 4-11
the (A5-A3) amplifier board, tune capacitors C104 and C204 for peak output power.
Tune C106 and C206 for peak output power with a flat-frequency response and
minimum current.
To adjust the idling currents, no RF applied to the tray, of the devices on the (A5-A4)
amplifier board, connect a voltage meter across E1 and E2 on the amplifier protection
board. Move switch S1 to the I10 position and adjust R106 for a reading of 2.5 mV.
Move switch S1 to the I9 position and adjust R206 for a reading of 2.5 mV.
Connect a sweep test signal to J1, the RF input jack of the 600-watt amplifier tray. On
the (A5-A4) amplifier board, tune capacitors C104 and C204 for peak output power.
Tune C106 and C206 for peak output power with a flat-frequency response and
minimum current.
To adjust the idling currents, no RF applied to the tray, of the devices on the (A5-A5)
amplifier board, connect a voltage meter across E1 and E2 on the amplifier protection
board. Move switch S1 to the I12 position and adjust R106 for a reading of 2.5 mV.
Move switch S1 to the I11 position and adjust R206 for a reading of 2.5 mV.
Connect a sweep test signal to J1, the RF input jack of the 600-watt amplifier tray. On
the (A5-A5) amplifier board, tune capacitors C104 and C204 for peak output power.
Tune C106 and C206 for peak output power with a flat-frequency response and
minimum current.
4.2.9 (A5-A6) 4-Way Combiner Board (1227-1311; Appendix B)
There are no adjustments to this board.
4.2.10 (A5-A7) Circulator
The circulator contains no adjustments.
4.2.11 (A6-A1) Dual Peak Detector Board, Single Supply (1227-1333; Appendix
B)
There are no adjustments to this board.
4.2.12 (A7) Amplifier Protection Board (1227-1306; Appendix B)
There are no adjustments to this board. One of the red LEDs, DS1 to DS13, will light if
the fuse associated with it is opened.
4.2.13 (A8) Amplifier Control Board (1227-1308; Appendix B)
To check the operation of the overdrive circuit, increase the gain pot of the 600-watt
amplifier tray to approximately 110%. The Overdrive LED DS2 should light and the
output power should not increase above the 110% level.
4.2.14 Calibration of Output Power and VSWR Cutback
To calibrate the output power and VSWR cutback of the 600-watt amplifier trays, place a
wattmeter and dummy load of at least 600 watts at the output of the tray that is to be
calibrated and switch the front panel meter to the % Output Power position. Preset R16,
manual gain, on (A8) the amplifier control board (1227-1308) fully CCW.