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RF Section Troubleshooting
Troubleshooting
If the power level is incorrect, the most probable cause is the YTF Preselector.
Reconnect W7 and W8 cables (or W31 and W34 cables).
The following High Band path items have been verified in the RF section:
— 4.8 GHz Calibrator signal power level from the A16 Reference Board
— 1st L.O. power level from the A14 L.O. Synthesizer
— Switch control logic from the A15 Front End Control Board to:
• Input Attenuator A
• Input Attenuator B
•Low Band Switch
• YTF Preselector
• RF Front End Assembly
— Input Attenuator A
— Input Attenuator B
—Low Band Switch
— YTF Preselector
If all the power levels and biasing from the A15 Front End Control board
measure correctly up to this point, the most probable cause would be the A13
Front End Assembly.
NOTE High Band #2 RF signal path utilizes a high band mixer internal to the A13 RF
Front End Assembly for RF input frequencies from 13.6 GHz to 26.5 GHz.
Since all the control voltages and biasing were already fully tested, failures
from 13.6 GHz - 26.5 GHz will most likely be caused by the A13 RF Front End
Assembly. If the failure is amplitude related, proper adjustments such as
frequency response and the YTF Preselector adjust should be performed first
before changing the A13 RF Front End Assembly. Refer to Chapter 11, “Block
Diagrams.” for details.
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