HP 8340B Manual page 256

5-9.
FM ACCURACY AND FM OVERMOD ADJUSTMENT (Cont'd)
Equipment
Spectrum Analyzer
.............................................
HP 8566B
Digital
Voltmeter
...............................................
HP 3456A
Function Generator
............................................
HP 3325A
Oscilloscope
...................................................
HP 1741A
Adapters:
APC 3.5(f) to TYPE
N(m) (2 required)
.....................
HP P/N 1250-1744
APC 3.5 (f) APC 3.5 (f) (8340B
only)
.......................
HP P/N 5061-5311
BNC(f) to dual banana
.................................
HP P/N 1251-2277
BNC Tee
............................................
HP P/N 1250-0781
Cables:
Semi-Rigid,
SMA (m) to SMA (m)
......................
HP P/N 08340-20124
BNC (m)
to
BNC (m)
(2
required)
..........................
HP P/N 8120-1840
PM GAIN
ADJUSTMENT
1.
Connect the equipment as shown in Figure
5-26, FM Accuracy
and Overmod Adjustment Setup.
The BNC Tee should be connected
directly
to the DUT's FM
input
BNC.
Switch the
DUT
to ON and
allow the equipment to warm up for 30 minutes.
2.
On the
DUT, press
[INSTR PRESET]
[CW][1][0][GHz]
[POWER LEVEL] [0] [dBm]
[FM]
Use the
DOWN ARROW step key to select an FM sensitivity of
1 MHz/V (default condition).
3.
Set the
DVM
to measure ac
volts.
Set up the function
generator for a
100
kHz
sine wave. Adjust
the
function
generator's amplitude for 0.16996 Vrms (measured on the DVM). You may not be able
to set the function generator's amplitude for this
exact voltage so adjust the voltage as close as
possible.
4.
Press [FM] on
the
DUT to turn FM
off.
Adjust the spectrum
analyzer to center
the DUT's
10
GHz
output (carrier frequency)
on the center of the display. Select
a
frequency span of 500 kHz.
5.
Press
[FM]
on the
DUT
to turn
FM on. Adjust A23R28 FM GAIN
to null
the carrier (i.e., reduce the
carrier's power
level as much as possible).
FM OVERMOD ADJUSTMENT
6. If the
YO
Loop
is
already disassembled, proceed
to step
7.
Remove
the
YO
Loop from the
DUT and remove the cover from the A49
YO Phase Detector
assembly.
In order
to remove the cover on the A49 assembly, the YO Loop
will
need
to be
disassembled. Reinstall the YO Loop
and place
it in the service position. Reinstall the ribbon cable
and
SMB
cables which
were
removed during disassembly.
5-54
Adjustments
HP 8340B/41B