Operation; Primary Function Control; Frequency Lock - TTI TG420 Manual Del Usuario

General
Switching On
When AC power is first connected the generator will go into its standby mode. Press the
OPERATE key to turn the generator on; press again to return to the standby mode.
Disconnect from the AC supply by unplugging the mains cord from the back of the instrument or
by switching off at the AC supply outlet; make sure that the means of disconnection is readily
accessible. Disconnect from the AC supply when not in use. The AC Power lamp lights to show
when the generator is connected to the supply.
Principles of Editing
The parameter to be changed is selected using the keys then set using the rotary control. The
currently selected parameter is indicated by the edit arrow. Turning the rotary control steps the
mode parameters through all the choices in turn, e.g. with FUNCTION selected the choices are
SINe, TRIangle, SQUare, and DC. With numerical parameters, e.g. FREQUENCY, the rotary
control increments (clockwise rotation) or decrements (anti-clockwise rotation) the value; turning
the control faster increments the value in bigger steps.
The keys have up to 3 possible functions. Their primary function is marked below the key; this is
the default function when the generator is turned on. In addition, pressing the EDIT key selects
the CONFIGuration level and SWEEP control level in turn; the selected level is indicated by
lighting the appropriate lamp. A further press of the EDIT key returns the keys to the primary
control level (neither lamp lit).

Primary Function Control

The primary functions, printed below the keys, are as follows:
Frequency Set
Pressing the FREQUENCY key at any time moves the edit arrow to the FREQ field in the top line
of the display. The frequency can then be set using the rotary control.
Frequency Range
Pressing the FREQUENCY key a second time displays the RANGE field in the lower line of the
display and moves the edit arrow to this field. Turning the rotary control steps the frequency
through the decade ranges in turn; the frequency display also changes in decades, in step with
the range.

Frequency Lock

In LOCK mode the output frequency is continuously compared with the internal crystal-controlled
timebase and corrected to give an accuracy of ± 0.05% ± 2 digits. Lock mode is set by holding
down the FREQUENCY key for ~2 seconds until an asterisk (∗) is shown to the right–hand side of
the displayed frequency, indicating that Lock mode has been selected. When Lock is selected,
allow 20 seconds for the frequency to stabilise. Frequency locking is only available on the 20kHz
to 20MHz ranges and should not be used when external FM is selected.
Lock mode is cancelled by changing the frequency or range or if the unit is put into standby.
DC Offset
Pressing the OFFSET key sets the edit arrow to the OFFSET field in the lower line of the display.
The DC offset can be adjusted using the rotary control within the range ± 10.0 Volts. DC offset
plus signal peak is limited to ± 10V. DC offset plus waveform is attenuated proportionally in the
–20dB and –40dB positions.
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Operation