Table 10-12. YTO Frequency Errors with A14J23 on Pins 2 and 3

(

 

YTO

Frequency Error

Gain of U328B

I

 

 

 

 

(with 523 on pins 2 and 3)

 

- 1 0 4 to - 93 MHz

 

-10 to +30 MHz

- 1

 

 

- 9 3

to - 73

MHz

 

-20to +20 MHz

- 1

- 7 3

to - 65

MHz

 

-30 to +10 MHz

- 1

+65

to +73 MHz

 

-10

to +30 MHz

+1

 

+73 to +93 MHz

 

-20

to +20 MHz

$1

 

+93to $104 MHz

 

-30

to +lO MHz

+1

 

 

 

 

 

 

 

 

10.The 1st LO’s pretuned frequency must be sufficiently accurate for the YTO loop to acquire lock. The 1st LO’s amplitude must be sufficient to drive the A15A2 Sampler. Perform the YTO Adjustment procedure, particularly the YTO Main Coil adjustments. (If available, use a synthesized microwave spectrum analyzer instead of the microwave frequency counter specified in the adjustment procedure.)

11.If the YTO’s main coil cannot be adjusted, proceed to step 33 to troubleshoot the Main Coil Coarse and Fine DACs and Main Coil Tune DAC.

12.The front-panel’s 1ST LO OUTPUT should measure between t14.5 and t18.5 dBm in amplitude. (>+12.5 dBm if Option 002 is present.)

13.If the 1ST LO OUTPUT amplitude is out of the specified range, perform the First LO Distribution Amplifier Adjustment procedure. Refer to Chapter 2.

14.Set the HP 8560A to the following settings:

C E N T E R F R E Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz

15.Monitor the Roller Oscillator PLL’s output at A14J304 (ROLLER TST) with a synthesized spectrum analyzer such as an HP 8568A/B or HP 8566A/B. Refer to function block AQ of Al4 Frequency Control Schematic (sheet 5 of 5).

16.The signal at A14J304 (ROLLER TST) should measure approximately -30 dBm at

94.7MHz.

17.If a problem exists only at particular CENTER FREQ and SPAN settings, determine

the desired Roller Oscillator frequency by pressing [CAL), MORE, FREQ DIAGNOSE,

MAIN ROLLER and setting the HP 8560A to SINGLE trigger mode.

18.If the Roller Oscillator frequency is not correct, refer to “Unlocked Roller Oscillator PLL” in this chapter.

19.Set jumper A14J23 to the TEST position and set the HP 8560A to the following settings:

CENTER FREQ . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 GHz SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz

20.Disconnect cable W34 from A15A2Jl.

21.Use a power meter to measure A7 LODA’s sampler-drive output at the end of W34. The power should measure greater than -9 dBm.

lo-28 Synthesizer Section