How To Set Pulse Modulation With An External; Source - HP 8642A Operation And Calibration Manual

Operation
Model 8642A/B
Modulation, Pulse (cont'd)
EXT DC
Example
Pulse modulate the RF output using the internal modulation oscillator at a 2 kHz rate
(starting with pulse modulation off).
LOCAL
(keys)
I
SHIFT
I
~
(program
codes)
Display
m
rl
T'FR
I
W
J,J.
~
ENTRY I MODULATION SOURCE ENTRY DATA
I
ENTRY
!
PULse
0 [1;J
OJ~I 8
PU:...sE
[]t)
0
fRED
o
ON
PLNT MF 2 KZ PLON
2.000
hi
Z
.....
PUL~E
_IU~'"
Tim'
I 1
/iW./iW
J,J
II
INT AM?TO
The RF output is being internally pulse modulated (as indicated by the word PULSE
and the annunciator INT). Modulation frequency is set to 2 kHz. The duty cycle is
50%. The cursor above the pulse modulation display indicates that pulse modulation
can be toggled off and on by selecting the I OFF ON I key. (Note that the AM
annunciator is displayed if the word "PULSE" can't be displayed.)
How to Set Pulse Modulation with an External Source
3-128
Source
Do not apply more than 15 Vpk to the AM/PULSE INPUT or
damage to the Signal Generator's circuitry could result.
Connect the external modulation source to the AM/PULSE INPUT connector (input
impedance of 600 ohms) and select PULSE ( ( SHIFT I
eNiD ) (
EXT DC
J.
Adjust the
external modulation signal to a level above 1.5 volts. Above 1.5 volts the output is on
and below 1.5 volts the output is off.
Pulse repetition rate and duty cycle are determined by the external pulse generating
source. (Note that the HI, LO annunciators are not used for pulse modulation.)
NOTE
External modulation freqency is not monitored by the Signal
Generator. The Signal Generator's modulation frequency display
refers to the internal modulation oscillator only.