Verify The Divider - HP 8340B Manual

10.
Using
a frequency synthesizer,
inject
a
250
MHz CW
signal,
at
0
dBm,
into the cable
marked
A36J2.
11. Connect
a
spectrum analyzer
to A38J1 and verify
a
CW output between 84 and
89.85 MHz, at
approximately —10
dBm.
If
this output
is
not correct, repair or
replace the A38 assembly.
12.
Disconnect the cables from the frequency synthesizer and the spectrum analyzer. Turn the
instru¬
ment's power switch to STANDBY.
13.
Reinstall the
A36 PLL1 VCO
and related coax cables. Leave the power switch in the
STANDBY
position and proceed
directly to
step
14.
Verifying the Operation of the A37
PLL1
Divider
14.
Place the
A37
PLL1
divider on an
extender
board. This closes the
PLL1
phase lock
loop.
Turn
the
instrument's power
switch on.
15.
Connect
a
spectrum analyzer to the cable marked
A37J1
and verify
a
CW
frequency of 10
MHz at
0
dBm.
If this signal
Is not correct,
troubleshoot the reference loop. Refer to the reference loop
—
M/N
loop section.
18.
Disconnect the spectrum
analyzer
and reconnect the cable
marked
A37J1 to A37J1.
VERIFY THAT THE PHASE/FREQUENCY DETECTOR WILL CAUSE THE VCO TO REACH
OPERATIONAL LIMITS.
17.
Connect
an
oscilloscope to the A37 PLL1
divider as follows:
Connect Channel
A to A37TP11
Connect Channel
B
to A37TP12
Set the Horizontal sweep time to
2
ns/div
18. Using
a frequency synthesizer,
inject
a
34
MHz,
-10 dBm
signal into the cable
marked A38J1,
19.
Monitor the
waveforms
on
the oscilloscope. Note that the waveform on channel
A is
pulsed.
20.
Change
the frequency synthesizer's output to 140
MHz. Note that
the waveform on channel
B is
pulsed.
21.
Force the phase/frequency detector to
reach operational
limits
by changing the output of the
frequency synthesizer to 145
MHz.
VERIFY THE N1 DIVIDER
22. Refer to the HP
8340B/41B
Calibration Manual and perform the
N1
loop frequency check as
described in
the Frequency
Range and CW Mode Accuracy test
in Section 4, Performance Tests.
23.
If
the instrument doesn't pass this test, troubieshoot the A37 PLL1 divider or the A59 digital
interface assemblies.
24. After performing all
tests, turn the instrument's power switch
to
STANDBY. Remove all
test leads.
Remove the extender board and reinstall the
A37 PLL1
divider. Reinstall all
cables and mounting
hardware.
HP 8340B/41B
20-30
Loops Assembly-Level Troubleshooting C-15/C-16