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62
Operation
Touchscreen Buttons
Touchscreen buttons on the display allow for direct keypad entry, text entry, calculator
functions, graph scaling and much more. This manual will refer to touchscreen buttons
with curly brackets such as {Button}.
Reset
To reset the unit, hold down the [Local] key while the power is turned on. The unit will
use the standard settings. A similar reset is available without cycling power by pressing
the [Save Recall] key and selecting {Recall default}.
Serial Number and Firmware Version
Press and hold [Local] and then [Auto Range] at the same time to display the unit serial
number and version numbers. Press [Screen Layout] to dismiss the informational screen.
Local Lockout
If a computer interface has placed the unit in the Local Lockout state, indicated by the
Remote
settings from the front panel will display a message 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 either 1 MΩ or 50 Ω. The
Sine Trig is ac coupled (>1 Hz). 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.
Sine Out
The internal oscillator outputs are differential with 50 Ω output impedance each. The
output amplitude is specified as Vrms differential into 50 Ω loads (amplitude = sine+ −
sine−). If the output is terminated in a high impedance, the amplitude will be double. If
only a single output is used, the amplitude will be half. Thus a single output into high
impedance will actually have the specified amplitude. The amplitude can be set from
1 nVrms to 2 Vrms.
The dc level of the sine output can also be specified. The dc can be applied differentially
(outputs move apart) or in common (outputs move together). The dc level can be set from
0.1 mV to 5 V. The maximum output is about ±6 V.
These outputs are 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 2.5 V sync logic output is provided on the rear panel via the configurable BlazeX
output. This output is useful for triggering scopes and other equipment at the reference
frequency. The sync output is a square wave derived from the zero crossings of the sine
output.
SR865A DSP Lock-in Amplifier
LED, then the keys, knobs and touchscreen are disabled. Attempts to change the
Chapter 3
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