Hameg HM 407A Manual

17Subject to change without noticeANALOG MODE ONLYAll trigger and time base related controls as well as the Y-POS. I (13) knob are deactivated. For X position alteration,the X-POS. (18) knob can be used.STORAGE MODE ONLYXY mode is indicated by the readout display ”XY” and theRFR-LED is lit. No other STOR. MODE (9) can be chosen.The readout displays the sampling rate (e.g. ”40MS/s”)which can be selected by the TIME/DIV. (28) knob.There are gaps in the display of Lissajous figures whenthe sampling rate is too high. Too low a sampling rate canresult in a display which does not permit the frequencyratio of the two signals to be determined. The selectionof a suitable sampling rate is simplified if both the signalsare first displayed in the refresh DUAL mode. The TIME/DIV control should be then so set that at least one periodof each signal is displayed. After this one can switch to theXY Digital mode.Attention!Note the following differences compared to the analogXY mode:The Y POS. I (13) control functions as X-Position controland the X-POS (18) control is disabled.(23) TRIG. - Pushbutton with double function for triggersource selection and associated LEDs.The button and the LEDs are deactivated if line (mains)triggering is selected or XY operation is chosen. In thelatter case this also applies to all trigger related controlsand LEDs.With the aid of this button, the trigger source can bechosen. There are three trigger sources available:channel I,channel II (both designated as internal trigger sources)and the TRIG. EXT. (33) input for external triggering.The availability of the internal sources depends on theactual channel mode. The actual setting is indicated bythe associated LED(s).Briefly pressing the button switches over in the followingsequence:I - II - EXT - I in DUAL and ADD (addition) mode,I - EXT - I if mono channel I is present,II - EXT - II under mono channel II conditions.Each condition is indicated by the associated LED. The triggerpoint symbol is switched off in external trigger condition.STORAGE MODE ONLYIn combination with ROLL mode, all controls and LEDsregarding trigger functions are disabled.ALT:Pressing and holding the button selects alternate triggeringin DUAL mode. Under these conditions both TRIG CH Iand CH II LEDs are lit. As alternate triggering requiresalternate channel operation, alternate channel switchingis set automatically. A change of the time coefficient thenhas no affect regarding the channel switching mode. Inaddition to the deflection coefficients display, “ALT” isdisplayed by the readout instead of “CHP”.In alternate trigger mode the trigger point symbol isswitched off.Alternate triggering is not available or automaticallyswitched off under the following conditions:ADD (addition) mode,TVL, TVF and line (mains) trigger coupling and the timebase modes which are available only in analog mode(search (SEA), delayed (DEL and DTR)).(24) VOLTS/DIV. - Control knob and associated LED.This control knob for channel II has a double function. Thefollowing description relates to the input attenuatorfunction (VAR-LED dark).This control knob is operative in those modes wherechannel II is active (CH II, DUAL, ADD and XY) and theinput coupling is not set to ground (GD (37)).Turning the control knob clockwise increases the sensitivity(decreases the deflection coefficient) in a 1-2-5 sequenceand decreases the sensitivity (increases the deflectioncoefficient) if turned in the opposite direction (ccw.). Theavailable range is from 1mV/div up to 20V/div. The knob isautomatically switched inactive if the channel related to it isswitched off, or if the input coupling is set to GD (ground).The deflection coefficients and additional informationregarding the active channel(s) are displayed in the readout,i.e. “Y2:...”deflection coefficient, input coupling” (”Y:...” inXY mode). The “:” symbolizes calibrated measuringconditions and is replaced by the “>” symbol in uncalibratedconditions.(25) CH II - VAR. - Pushbutton with several functions.CH IIBriefly pressing the CH I button sets the instrument tochannel II (Mono CH I) mode. The deflection coefficientdisplayed in the readout indicates the current conditions(“Y2...”). If neither external nor line (mains) triggeringwas active, the internal trigger source automaticallyswitches over to channel II (TRIG.-LED (23) CH I lits). Thelast function setting of the VOLTS/DIV (24) knob remainsunchanged.All channel I related controls are active if the input (35) isnot set to GD (37).VAR.Pressing and holding this pushbutton selects the VOLTS/DIV. (24) control knob function between attenuator andControls and readout