Stanford Research Systems DS345, Manual

Page: 22 / 139

DS345 FEATURES
2-6
any associated units and
any
of the units keys may be used to enter the value. When the amplitude is dis-
played, pressing a units key without entering a new value will displayed the amplitude in the new units. This
allows the am plitude display to be switched between Vpp, Vrms, and dBm without entering a new value.
5) Shift Key
The shift key is used to select the functions printed in gray above the keys.
Press [SHIFT] and then [key] to select the desired function (for example
[SHIFT][SWP CF] to display the sweep center frequency). When the SHIFT
key is pressed the SHIFT LED will light. This indicates that the keyboard is in
shift mode. Pressing [SHIFT] a second time will deactivate shift mode.
6) Modulation Keys
These keys control the DS345's modulation capabilities. The MODULATION
TYPE up/down arrow keys select the modulation type. The MODULATION
WAVEFORM up/down arrow keys select the waveform of the modulating
function. The [SWEEP ON/OFF] key turns the modulation on and off. When
the modulation is turned on the MOD/SWP LED will light. If the modulation
parameters are not permitted for the selected output function, an error mes-
sage will be displayed and modulation will not be turned on. Some modula-
tion parameters are not relevant to all modulation types (start frequency is
not relevant to AM, for example), and the message "NOT APPLIC" will be
displayed if they are selected.
7) Function Keys
These keys choose the main function output. The FUNCTION up/down arrow
keys select between the output functions. If the output frequency is set be-
yond of the range allowed for a waveform (> 100 kHz for triangle and ramp) a
message will be displayed and the frequency will be set to the maximum al-
lowed for that function.
8) Main Function BNC
This output has an impedance of 50
Ω
. If it is terminated into an impedance
other than 50
Ω
the output amplitude will be incorrect and may exhibit in-
creased distortion. The shield of this output may be floated up to ±40V rela-
tive to earth ground.
9) Sync Output BNC
This output is a TTL square wave synchronized to the main function output
and has a 50
Ω
output impedance. The shield of this output may be floated up
to ±40V relative to earth ground.
10) Status LEDs
These six LEDs indicate the DS345's status. The LED functions are:
name function
REM The DS345 is in GPIB remote state. The STEP SIZE key re-
turns local control.
SRQ The DS345 has requested service on the GPIB interface.
ACT Flashes on RS232/GPIB activity.
ERR Flashes on an error in the execution of a remote command.
EXT CLOCK The DS345 has detected a signal at its TIMEBASE input and
is trying to phase lock to it.
CLOCK ERR The DS345 is unable to lock to the signal at the TIMEBASE
input. This is usually because the signal is too far (>2ppm)
from the nominal values of 10, 5, 3.33, 2.5 or 1.25 MHz.
11) Parameter Display
This 12 digit display shows the value of the currently displayed parameter.
The LEDs below the display indicate which parameter is being viewed. Error
messages may also appear on the display. When an error message is dis-
played you can return to the normal operation by pressing any key.