Hameg HM 407A Manual

16 Subject to change without noticeTurning 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 knobis automatically switched inactive if the channel related toit is switched 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. “Y1:...”deflection coefficient, input coupling” (”X:...”in XY mode). The “:” symbolizes calibrated measuringconditions and is replaced by the “>” symbol in uncalibratedconditions.(21) CH I - VAR. - Pushbutton with several functions.CH IBriefly pressing the CH I button sets the instrument tochannel I (Mono CH I) mode. The deflection coefficientdisplayed in the readout indicates the current conditions(“Y1...”). If neither external nor line (mains) triggeringwas active, the internal trigger source automaticallyswitches over to channel I (TRIG.-LED (23) CH I lits). Thelast function setting of the VOLTS/DIV (20) knob remainsunchanged.All channel I related controls are active if the input (31) isnot set to GD (33).VAR.Pressing and holding this pushbutton selects the VOLTS/DIV. (20) control knob function between attenuator andvernier (variable). The current setting is displayed by theVAR-LED located above the knob.After switching the VAR-LED (20) on, the deflectioncoefficient is still calibrated. Turning the VOLTS/DIV.(20) control knob counter clockwise reduces the signalheight and the deflection coefficient becomesuncalibrated.The readout then displays i.e. “Y1>...” indicating theuncalibrated condition instead of “Y1:...”. Pressing andholding the CH I pushbutton again switches the LED off,sets the deflection coefficient into calibrated conditionand activates the attenuator function. The previous verniersetting will not be stored.The CH I pushbutton can also be pressed simultaneouslywith the DUAL (22) button.Please note item (22).(22) DUAL - XY - Pushbutton with multiple functions.DUAL modeBriefly pressing this button switches over to DUALmode. Both deflection coefficients are then displayed.The previous trigger setting stays as it was, but can bechanged.All controls related to both channels are active, if theinputs (31) and (35) are not set to GD (33) (37).Whether alternated or chopped channel switching ispresent depends on the actual time base setting, and isdisplayed in the readout.ALTdisplayed in the readout, indicates alternate channelswitching. After each time base sweep the instrumentinternally switches over from channel I to channel II andvice versa. This channel switching mode is automaticallyselected if any time coefficient from 200μs/div to 50ns/div is active.CHPindicates chopper mode, whereby the channel switchingoccurs constantly between channel I and II during eachsweep. This channel switching mode occurs when anytime base setting between 500ms/div and 500μs/div hasbeen chosen. The actual channel switching can be changedto the opposite mode by briefly pressing both CH I (21)and DUAL (22) simultaneously. If afterwards the timecoefficient is changed, the channel switching isautomatically set to the time coefficient related mode.STORAGE MODE ONLYThe signal acquisition is carried out with both A/Dconverters in the two channel (DUAL) digital mode. Sincethere is no need to switch channels as in analog mode,the readout display shows the signal acquisition modeinstead of ALT or CHP.ADD modeAddition mode can be selected by briefly pressing theDUAL (22) and CH II (25) pushbuttons simultaneously.Whether the algebraic sum (addition) or the difference(subtraction) of both input signals is displayed, dependson the phase relationship and the INV (37) setting. As aresult both signals are displayed as one signal.For correct measurements the deflection coefficients forboth channels must be equal.Please note “Operatingmodes of the vertical amplifiers in Yt mode”.The readout indicates this mode by a “+” sign locatedbetween both channel deflection coefficients. While thetrigger mode is not affected, the trigger point symbol isswitched off.The Y-position of the signal can be influenced by both Y-POS controls (13) and (14).XY modeThis mode can be switched on or off by pressing andholding the DUAL button (22).In XY mode the deflection coefficients are displayed as“X...” for channel I and “Y...” for channel II, followed by“XY”. Consequently INPUT CH I (31) serves as an X-input and INPUT CH II (35) is used for Y-deflection. TheX-MAG x10 (19) function is automatically switched off.The cursor lines may be active, but the trigger point andthe 0 Volt reference symbols are switched off.Controls and readout