UBS Axcera 835-3 UHF television transmitter User Manual

UBS-Axcera UHF television transmitter Users manual for equipment

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Chapter 4

3-kW UHF Transmitter Chapter 4, Detailed Alignment Procedures835-3, Rev. 0 4-1Chapter 4Detailed Alignment ProceduresBefore beginning the alignment procedures, make sure that the RF output at J2 of (A11)the output coupler assembly of the transmitter is terminated into a dummy load of atleast 3000 watts. While performing the alignment, refer to the test data sheet for thetransmitter and compare the final readings from the factory with the readings on eachof the trays. The readings should be very similar. If one of the readings is off by asignificant degree, the problem is likely to be in that tray.Switch on the UHF exciter tray circuit breaker on the AC distribution panel in the UHFexciter cabinet and the circuit breaker on the rear of the UHF exciter tray for the 3-kWtransmitter. Also switch on the main and the individual amplifier circuit breakers on theAC distribution panel in the amplifier array cabinet.4.1 (A1) UHF Exciter Tray (1227-1200; Appendix A)The (A1) UHF exciter tray has been factory tuned and should need no alignment toachieve normal operation. Apply the baseband video and audio inputs of the test signals,as needed, to the A/V input and remote interface panel on the rear of the transmitter. 4.1.1 (Optional) (A6) Delay Equalizer Board (1227-1204; Appendix B)This board may not be present in the tray.This board has been factory tuned and should not be re-tuned without the properequipment. To align this board:• Connect a sinX/X test signal into jack J1-2 on the delay equalizer board.• Monitor the video output of the board at video sample jack J2 with a videomeasuring set VM700 adjusted to measure group delay.• Tune the four stages of the board using the variable inductors (L1-L4) andpotentiometers (R7, R12, R17, and R22) until the signal attains the FCC group delaycurve. The stages are arranged in order of increasing frequency. Adjust R29, ifneeded, for the desired video gain.4.1.2 (A7) IF Carrier Oven Oscillator Board (1191-1404; Appendix B)While monitoring J3 with a spectrum analyzer, observe the 45.75 MHz visual IF (+5dBm).Connect a frequency counter to J3 and adjust C17 for 45.750000 MHz.Connect a frequency counter to J1 and check for 50 kHz; this is the aural phase lockloop reference.4.1.3 (A5) Clamp/Modulator Board (1227-1208; Appendix B)Determine if jumper W1 on jack J3 is present. Jumper W1 terminates the video inputinto 75 ohms. Remove jumper W1 if video loop-through is required on the rear chassisjacks J1 and J2.
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Document ID108440
Application IDNGywfngW/saIIG3C96KN8w==
Document DescriptionChapter 4
Short Term ConfidentialNo
Permanent ConfidentialNo
SupercedeNo
Document TypeUser Manual
Display FormatMicrosoft Word - pdf
Filesize7.86kB (98305 bits)
Date Submitted2000-07-10 00:00:00
Date Available2000-08-16 00:00:00
Creation Date2000-07-10 11:40:06
Producing SoftwareAcrobat Distiller 4.0 for Windows
Document Lastmod2000-07-10 11:40:08
Document TitleChapter 4
FCC ID Filing: OUS835-3

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