sired amplitude with OUTPUT VERNIER (dB)
control.
Operation as a Random FM Source
Before using the generator as a random FM source,
please note the following.
The frequency of the generator is being varied or
modulated by a changing voltage in the same way as
described in “Operation as a Voltage Controlled Gen-
erator.” However, instead of using a dc ramp, or ac
signal, a random analog voltage is used. When the FM
push button is depressed, the analog noise is injected
internally into the VCG circuit; therefore, the modu-
lation is created by random noise. The S/N - N/S (dB)
knob controls the maximum amount of frequency
deviation, since it controls the amplitude of the noise.
Bandwidth of the FM signal is controlled by the
NOISE FREQ HZ control. Using the generator in the
FM mode may be accomplished as follows:
1.
2.
3.
4.
5.
6.
7.
Select the desired signal waveform by setting
function selector to
,
, or
.
Set frequency dial and FREQ HZ range multi-
plier for desired center output frequency.
Depress MODE - FUNC and FM push buttons.
Select the bandwidth by setting NOISE FREQ
HZ control to desired range and fine adjusting
frequency by turning the noise frequency Hz
vernier control.
Select desired SEQUENCE LENGTH by depres-
sing appropriate push button.
Select signal frequency deviation by setting
S/N - N/S (dB) control to appropriate attenua-
tion position and fine adjusting attenuation to
desired deviation with S/N - N/S vernier control.
Select output signal amplitude by setting OUT-
PUT ATTEN (dB) control to appropriate atten-
uation position and fine adjusting signal to de-
sired amplitude with OUTPUT VERNIER (dB)
control.
Operation as a Digital or Analog Noise Source
Figure 2-2. Common Ground Connection Diagram
1.
2.
3.
Set function selector to digital or analog noise
position.
Depress MODE - FUNC push button.
Select clock frequency for digital or bandwidth
for analog noise by setting NOISE FREQ HZ
control to desired range and fine adjusting fre-
quency by turning the noise frequency Hz ver-
nier control.
4.
5.
Select desired SEQUENCE LENGTH by depres-
sing appropriate push button.
Select noise amplitude by setting OUTPUT
ATTEN (dB) control to appropriate attenuation
position and fine adjusting noise to desired
amplitude with OUTPUT VERNIER (dB) con-
trol.
Connect Signal and Chassis Grounds
The instrument is shipped from the factory with the
signal ground floating above chassis ground, unless
otherwise specified. A common signal/chassis ground
can be obtained as follows:
1.
2.
3.
Remove power cord.
Loosen two captive thumb screws on rear panel
and remove panel.
Solder a jumper wire between the ground lugs
(green wires) of the SYNC OUT connector and
the power connector (Figure 2-4).
ADD
JUMPER
POWER
C O N N E C T O R J1
BRACKET
POWER
SYNC
DC OFFSET
T R A N S F O R M E R O U T
R 172/SW4
T1
CONNECTOR J3
Converting Output Impedance to 600 Ohms
Unlessotherwise specified, this instrument was shipped
with 50 ohm output impedance, but can be converted
to 600 ohm output if needed. Place a
resistor
in series with the wire leading from the center tap of
the
OUT BNC and the attenuator control.
9