Chapter 11 559
Synthesizer Section
Unlocked YTO PLL
49.Measure the output of the main coil tune DAC (A14J18 pin 3) with a
DVM. Refer to function block E of A14 frequency control schematic
(sheet 2 of 5).
50.If the spectrum analyzer center frequency is 300 MHz, the voltage at
A14J18 pin 3 should measure −3.35 V ±0.25 V. The voltage may also
be determined from the following equation:
V = −(1st LO Frequency −2.95 GHz) × 2.654 V/GHz
51.The voltage at A14U330 pin 2 should measure −3.4 V ±0.2 Vdc. This
represents a current setting the YTO to approximately 2.95 GHz.
52.Return A14J23 jumper to the NORMAL position.
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