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Operation and Reference
A dc voltage may be applied to the Amptd Mod input to control the HP 3325B output level,
or a pulse may he used to gate the output. Approximately 4-5V cuts off the output signal,
while approximately -5V doubles the output (maximum input is 10 Vpp). DC or pulse inputs
should not exceed ±5 Vpk. The impedance of the Amptd Mod input is 10 kH (5 Ml when
AM is off).
Phase Modulation
The [0M] (phase modulation) keys in the data group enable and disable
phase modulation of the Main Signal. Phase modulation is enabled by
pressing the [0M On] ([Shift] [Clear]) key, which illuminates the OM
modulation indicator. Phase modulation is disabled by pressing the [OM Off]
([Shift] [-]) key, which extinguishes the OM modulation indicator, or by
presetting the HP 3325B. The modulating signal is applied to the HP 3325B
through the rear-panel Phase Mod In connector.
The phase modulation signal at the rear-panel Phase Mod Input connector should not exceed
±10 Vpk,. The input impedance is 40 kO. The modulation signal frequency may be dc to
5 kHz. An input of ±5V results in the following approximate phase deviation (±170° per volt
for the sine function):
HP 3325B Function
Phase Deviation
Sine
Square
Triangle
±Ramp
±850°
±425°
±42.5°
±85°
Modulation Source
Mm Soura* Out
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The modulation source provides a second independent signal source,
available at the rear-panel Mod Source Out connector. This signal may be
used to modulate the main signal by connecting the mod source out
connector to the (amplitude or phase) input modulation connector(s) and
then controlling main signal modulation and the mod source signal.
The Mod Source output signal should be connected to the Phase or Amplitude
Modulation input connector with a BNC coaxial connector at the rear panel There
is no interna! connection.
0
o
T.
Arb
6
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2kHz
The modulation source is enabled by pressing the Mod Source sine wave
or square wave key. The modulation source is disabled by pressing the Mod
Source sine wave or square wave key adjacent to the illuminated Mod
Source indicator to extinguish that indicator.
-
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The Mod Source amplitude is entered by pressing the [Shift] key followed by
the [Amptd] key. The Modulation Source indicator to the left of the display
illuminates to indicate the display contains a modulation source value. Valid
modulation source amplitudes range from 0.1 to 12 Vpp with O.IV
resolution. Amplitudes may be entered in either Vpp or Vrms-
1-29
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