Stanford Research Systems SR830, Руководство пользователя

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4-2
Front Panel
Knob
The knob is used to adjust parameters in the Reference display. The
parameters which may be adjusted are internal reference frequency, ref-
erence phase shift, sine output amplitude, harmonic detect number, off-
sets, Aux Output levels, and various Setup parameters.
Local Lockout
If the computer interface has placed the unit in the REMOTE state, indi-
cated by the REMOTE led, then the keys and the knob are disabled.
Attempts to change the settings from the front panel will display the mes-
sage 'LOCL LOut' indicating local control is locked out by the interface.
Reference Input
The reference input can be a sine wave (rising zero crossing detected) or
a TTL pulse or square wave (rising or falling edge). The input impedance
is 1 M
Ω
AC coupled (>1 Hz) for the sine input. For low frequencies (<1
Hz), it is necessary to use a TTL reference signal. The TTL input pro-
vides the best overall performance and should be used whenever possi-
ble.
Sine Out
The internal oscillator output has a 50
Ω
output impedance and varies in
amplitude from 4 mVrms to 5 Vrms. The output level is specified into a
high impedance load. If the output is terminated in a low impedance,
such as 50
Ω
, the amplitude will be less than the programmed amplitude
(half for a 50
Ω
load).
This output is active even when an external reference is used. In this
case, the sine wave is phase locked to the reference and its amplitude is
programmable.
A TTL sync output is provided on the rear panel. This output is useful for
triggering scopes and other equipment at the reference frequency. The
TTL sync output is a square wave derived from the zero crossings of the
sine output.
CH1 & CH2 Outputs
The Channel 1 and Channel 2 outputs can be configured to output a volt-
age from -10 V to +10 V proportional to X or Y or the CH1 and CH2
Displays. ±10 V is full scale. The outputs can source 10 mA maximum.
Signal Inputs
The input mode may be single-ended, A, or differential, A-B. The A and B
inputs are voltage inputs with 10 M
Ω
, 25 pF input impedance. Their con-
nector shields are isolated from the chassis by 10
Ω
(Ground) or 1 k
Ω
(Float). Do not apply more than 50 V to either input. The shields should
never exceed 1 V. The I (current) input is 1 k
Ω
to a virtual ground.
Key Click On/Off
Press the [Phase] and [Harm#] keys together to toggle the key click on
and off.
Front Panel Display Test
To test the front panel displays, press the [Phase] and [Freq] keys
together. All of the LED's will turn on. Press [Phase] to decrease the
number of on LED's to half on, a single LED and no LED's on. Use the
knob to move the turned on LED's across the panel. Press [Freq] to
increase the number of on LED's. Make sure that every LED can be
turned on. Press any other key to exit this test mode.
Display Off Operation
To operate with the front panel displays off, press [Phase] and [Freq]
together to enter the front panel test mode. Press [Phase] to decrease