HP 8340B Manual page 81

4-16.
FM ACCURACY AND FLATNESS (Cont'd)
3. Press
[INSTR PRESET] on the HP 3585A
and set up as follows:
Start Frequency:
50 kHz
Stop Frequency:
10MHz
Resolution BW:
10
kHz (default condition)
Video BW: 1
kHz
Turn the
HP 3585A's TRACKING GENERATOR knob
fully clockwise.
NOTE
Steps
4
and
5
normalize the frequency response variations due
to the HP
3585A's tracking generator, HP 3550
step attenuator,
HP 8447F
ampli¬
fier,
and cables.
4.
Set
up
the HP 3585A
as follows:
NOTE
In
the following text, the operator
is instructed to
press
the REF LVL key.
This
key
is
actually marked REF LVL. Do not press the REFERENCE
LEVEL, REF LEVEL VOLT, or MKR—REF LVL keys.
Press
[MANUAL] [1] [MHz] [dB/DIV] [2] [dB].
Press
[REF LVL]. The [REF LVL] key
is
to the left of the rotary knob,
in the
MARKER/CONTINU¬
OUS ENTRY
section of the front panel.
Press
[CLEAR A]
and turn the rotary knob until
the marker
is 5
divisions up from the bottom
horizontal graticule.
Make
sure the OVER RANGE message does
not
come
on.
Turn
off the Autorange
function.
Adjust the RANGE
if
the
OVER RANGE message comes
on.
5.
Press
[CONT] sweep
to take
a swept response
of the signal path. When
a
full
sweep
is com¬
pleted, press
[STORE
A^B]
and [A-B]. Turn
VIEW B
OFF.
A
strait line should be displayed across the center of the
HP 3585A CRT.
Press
[SAVE] [1]
on the
HP 3585A.
NOTE
Steps
6
through
9
find the
OUT output frequency that places the mixer
inputs in quadrature
(90° out of phase).
6.
Press [RECALL]
[1]
on
the HP
3585A. Make
sure the
DUT
is set to the desired
CW
frequency.
Move the output of the HP 8447F
to the
DUT's AM
input.
Connect
the output of the mixer to the HP
3585A 50 Ohm
input.
7.
AM
is used to find
a
quadrature frequency that is
close to the desired
FM
flatness test frequency.
This is
done because at quadrature,
AM
is
rejected and FM response
is maximized.
On the DUT,
turn
AM
ON.
Make
sure FM
is
turned OFF.
8.
Set
up the HP 3585A
as follows:
Turn
A-B
OFF. Press [dB/DIV] [1] [0] [dB] [MANUAL] [1] [0] [0] [kHz].
Press
[CLEAR A].
4-80
Performance Tests
HP 8340B/41B