4.Measure the YTO frequency at the front-panel’s 1ST LO OUTPUT jack and record below:

YTO Frequency (measured) =

 

MHz

-----------------------

I’ A l 4 F R E Q U E N C Y C O N T R O L A S S E M B L Y /

!

M A I N C O I L T U N I N G I

F M C O I L

T U N I N G I

---I I

-IT I -

SAMPLER

I - -

J304

-15 T O

OdBm

R O L L E R T E S T

63 TO 105 5 MHz

A P P R O X - 3 0 dBm

W H E N LOCKED,SAME

63 TO 105 5 MHz

A S M A I N

R O L L E R F R E Q

M A I N R O L L E R F R E O

 

 

- -s--- ---

S K 1 1 0 8

Figure 10-8. Troubleshooting an Unlocked YTO PLL

5.Calculate the YTO’s frequency error by subtracting the frequency recorded in step 3 from the frequency recorded in step 4. Record the result below:

YTO Frequency Error =

 

MHz

 

YTO Frequency Error = YTO Frequency (MEASURED) -YTO FreqUenCy(CALCuLATED)

6.On the HP 8560A, press MORE, FREQ DIAGNOSE, and MAIN ROLLER. Record the Main Roller frequency below:

Main Roller Frequency = MHz

7.If the YTO Frequency Error recorded in step 5 is greater than 30 MHz, do the following:

a.Check the YTO Adjustments using the TAM or the procedure in Chapter 2.

b.Check the YTO DACs using the procedure in steps 41 through 49 below, or using Manual Probe Troubleshooting with the TAM on A14J17 and A14J18.

c.Refer to steps 10 through 34 below.

lo-26 Synthesizer Section