Filter
Top Products
5. Calculate the YTO 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 spectrum analyzer, press
M#RE
1
OF 2,
FRIQ
I3IKlKlSE,
and
FR&C
IV
FREq
.
Record the fractional N frequency below:
Fractional N frequency =
MHz
Caution
Replacement of the phase/frequency detector chip A14U204 is not
recommended. The part is very delicate and requires special tooling to install
successfully.
7. If the YTO frequency error recorded in step 5 is greater than 20 MHz, do the following:
a. Check the YTO Adjustments using the TAM or the procedure in Chapter 2,
“Adjustment Procedures.”
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 9 through 34 below.
8. If the YTO Frequency error recorded in step 5 is less than 20 MHz, do the following:
a. Measure the frequency at A14J304. The frequency should be equal to the frequency
recorded in step 6. If not, refer to “Unlocked Fractional N PLL” in this chapter.
b. Measure the input and output levels of the
A15UlOO
sampler. If the sampler appears
defective, check the LO drive to the sampler as described in “Sampler and Sampler
IF.”
c. Refer to steps 34 through 51 below.
Check First LO pretune frequency and amplitude (steps 9-12)
9. The pretuned frequency of the first LO must be sufficiently accurate for the YTO loop
to acquire lock. The amplitude of the first LO must be sufficient to drive the
A15UlOO
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.)
10. If the YTO main coil cannot be adjusted, proceed to step 33 to troubleshoot the main coil
coarse and fine DACs and main coil tune DAC.
11. The front-panel first LO OUTPUT should measure between
t14.5
and
t18.5
dBm
in
amplitude.
12. If the first LO OUTPUT amplitude is out of the specified range, perform the first
LO distribution amplifier adjustment procedure. Refer to Chapter 2, “Adjustment
Procedures.”
1
l-26
Synthesizer Section