Local Lockout; Key Click On/Off; Front Panel Display Test; Display Off Operation - Stanford Research Systems SR810 Manual

Front Panel

Local Lockout

Reference Input
Sine Out
CH1 Output
Signal Inputs

Key Click On/Off

Front Panel Display Test

Display Off Operation

reference phase shift, sine output amplitude, harmonic detect number,
offsets, Aux Output levels, and various Setup parameters.
If the computer interface has placed the unit in the REMOTE state,
indicated by the REMOTE led, then the keys and the knob are disabled.
Attempts to change the settings from the front panel will display the
message 'LOCL LOut' indicating local control is locked out by the
interface.
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 MΩ 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 provides the best overall performance and should be used
whenever possible.
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.
The Channel 1 output can be configured to output a voltage from -10 V
to +10 V proportional to X or the CH1 Display. ±10 V is full scale. The
outputs can source 10 mA maximum.
The input mode may be single-ended, A, or differential, A-B. The A and
B inputs are voltage inputs with 10 MΩ, 25 pF input impedance. Their
connector shields are isolated from the chassis by 10 Ω (Ground) or
1 kΩ (Float). Do not apply more than 50 V to either input. The shields
should never exceed 1 V. The I (current) input is 1 kΩ to a virtual ground.
Press the [Phase] and [Harm#] keys together to toggle the key click on
and off.
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.
To operate with the front panel displays off, press [Phase] and [Freq]
together to enter the front panel test mode. Press [Phase] to decrease
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