Oscilloscope HM303-6 - Rohde & Schwarz · Oscilloscope HM 303-6 3. ... HAMEG instruments fulﬁ ll the regulations of the EMC directive. The conformity test made by HAMEG is based

O s c i l l o s c o p eH M 3 0 3 - 6

Manual

English

Subject to change without notice2

Contents

General information regarding the CE marking ........... 4

General Information ......................................................... 6Symbols ........................................................................... 6General Information ........................................................ 6Use of tilt handle ............................................................. 6Safety .............................................................................. 6Intended purpose and operating conditions ................... 6Warranty .......................................................................... 7Maintenance .................................................................... 7Protective Switch-Off ...................................................... 7Power supply ................................................................... 7

Type of signal voltage ...................................................... 8Amplitude Measurements .............................................. 8Voltage values of a sine curve ........................................ 8Total value of input voltage ............................................. 9Time Measurements ....................................................... 9Connection of Test Signal ............................................. 10

First Time Operation ...................................................... 11Trace Rotation TR .......................................................... 11Probe compensation and use ....................................... 11Adjustment at 1kHz ....................................................... 11Adjustment at 1MHz ..................................................... 12

Operating modes ofthe vertical amplifiers .................................................... 12

X-Y Operation ................................................................ 13Phase comparison with Lissajous figures .................... 13Phase difference measurement .................................... 13

in DUAL mode ............................................................... 13Phase difference measurement in DUAL mode........... 14Measurement of an amplitude modulation .................. 14

Triggering and time base .............................................. 14Automatic Peak (value) - Triggering .............................. 15Normal Triggering .......................................................... 15Slope ...................................................................... 15Trigger coupling ............................................................. 15Line triggering (~) .......................................................... 16Alternate triggering ....................................................... 16External triggering ......................................................... 16Trigger indicator ............................................................ 16Holdoff-time adjustment ............................................... 16

Component Tester .......................................................... 17General .......................................................................... 17Using the Component Tester ........................................ 17Test Procedure .............................................................. 17Test Pattern Displays .................................................... 17Testing Resistors .......................................................... 17Testing Capacitors and Inductors ................................. 17Testing Semiconductors ............................................... 18Testing Diodes .............................................................. 18Testing Transistors ........................................................ 18In-Circuit Tests .............................................................. 18

Front Panel Elements HM 303-6(Brief Description - Front View) ............................... 20

Short Instruction for HM303-6 ...................................... 22

Oscilloscope

HM 303-6

3

3Subject to change without notice

General information regarding the CE marking

HAMEG instruments fulfi ll the regulations of the EMC directive. The conformity test made by HAMEG is based on the actual generic- and product stan-dards. In cases where different limit values are applicable, HAMEG applies the severer standard. For emission the limits for residential, commercial and light industry are applied. Regarding the immunity (susceptibility) the limits for industrial environment have been used.

The measuring- and data lines of the instrument have much infl uence on emmission and immunity and therefore on meeting the acceptance limits. For different applications the lines and/or cables used may be different. For measurement operation the following hints and conditions regarding emission and immunity should be observed:

1. Data cablesFor the connection between instruments resp. their interfaces and external devices, (computer, printer etc.) suffi ciently screened cables must be used. Without a special instruction in the manual for a reduced cable length, the maximum cable length of a dataline must be less than 3 meters and not be used outside buildings. If an interface has several connectors only one connector must have a connection to a cable.

Basically interconnections must have a double screening. For IEEE-bus purposes the double screened cables HZ72S and HZ72L from HAMEG are suitable.

2. Signal cablesBasically test leads for signal interconnection between test point and instrument should be as short as possible. Without instruction in the manual for a shorter length, signal lines must be less than 3 meters and not be used outside buildings.

Signal lines must screened (coaxial cable - RG58/U). A proper ground connection is required. In combination with signal generators double screened cables (RG223/U, RG214/U) must be used.

3. Infl uence on measuring instruments.Under the presence of strong high frequency electric or magnetic fi elds, even with careful setup of the measuring equipment an infl uence of such signals is unavoidable.This will not cause damage or put the instrument out of operation. Small deviations of the measuring value (reading) exceeding the instruments spe-cifi cations may result from such conditions in individual cases.

4. RF immunity of oscilloscopes.

4.1 Electromagnetic RF fi eldThe infl uence of electric and magnetic RF fi elds may become visible (e.g. RF superimposed), if the fi eld intensity is high. In most cases the coupling into the oscilloscope takes place via the device under test, mains/line supply, test leads, control cables and/or radiation. The device under test as well as the oscilloscope may be effected by such fi elds.

Although the interior of the oscilloscope is screened by the cabinet, direct radiation can occur via the CRT gap. As the bandwidth of each amplifi er stage is higher than the total –3dB bandwidth of the oscilloscope, the infl uence RF fi elds of even higher frequencies may be noticeable.

4.2 Electrical fast transients / electrostatic dischargeElectrical fast transient signals (burst) may be coupled into the oscilloscope directly via the mains/line supply, or indirectly via test leads and/or control cables. Due to the high trigger and input sensitivity of the oscilloscopes, such normally high signals may effect the trigger unit and/or may become visible on the CRT, which is unavoidable. These effects can also be caused by direct or indirect electrostatic discharge.

KONFORMITÄTSERKLÄRUNGDECLARATION OF CONFORMITYDECLARATION DE CONFORMITE

Hersteller HAMEG Instruments GmbH Manufacturer Industriestraße 6 Fabricant D-63533 Mainhausen

Die HAMEG GmbH bescheinigt die Konformität für das Produkt

The HAMEG GmbH herewith declares conformity of the product

HAMEG GmbH déclare la conformite du produit

Bezeichnung / Product name / Designation:

Oszilloskop/Oscilloscope/Oscilloscope

Typ / Type / Type: HM303-6

mit / with / avec: —

Optionen / Options / Options: —

mit den folgenden Bestimmungen / with applicable regulations / avec les directives suivantes

EMV Richtlinie 89/336/EWG ergänzt durch 91/263/EWG, 92/31/EWG EMC Directive 89/336/EEC amended by 91/263/EWG, 92/31/EEC Directive EMC 89/336/CEE amendée par 91/263/EWG, 92/31/CEE

Niederspannungsrichtlinie 73/23/EWG ergänzt durch 93/68/EWGLow-Voltage Equipment Directive 73/23/EEC amended by 93/68/EECDirective des equipements basse tension 73/23/CEE amendée par 93/68/CEE

15.01.2001

Angewendete harmonisierte Normen / Harmonized standards applied / Normes harmonisées utiliséesSicherheit / Safety / Sécurité

EN 61010-1: 1993 / IEC (CEI) 1010-1: 1990 A 1: 1992 / VDE 0411: 1994EN 61010-1/A2: 1995 / IEC 1010-1/A2: 1995 / VDE 0411 Teil 1/A1: 1996-05Überspannungskategorie / Overvoltage category / Catégorie de surtension: IIVerschmutzungsgrad / Degree of pollution / Degré de pollution: 2

Elektromagnetische Verträglichkeit / Electromagnetic compatibility / Compatibilité électromagnétique

EN 61326-1/A1 Störaussendung / Radiation / Emission: Tabelle / table / tableau 4; Klasse / Class / Classe B.Störfestigkeit / Immunity / Imunitee: Tabelle / table / tableau A1.

EN 61000-3-2/A14Oberschwingungsströme / Harmonic current emissions / Émissions de courant harmoni-que: Klasse / Class / Classe D.

EN 61000-3-3Spannungsschwankungen u. Flicker / Voltage fl uctuations and fl icker / Fluctuations de tension et du fl icker.

Datum /Date /Date Unterschrift / Signature /Signatur

E. Baumgartner Technical Manager /Directeur Technique

HAMEG Instruments GmbH

General information regarding the CE marking

For IEEE-bus purposes the double screened cable HZ72 from HAMEG is suitable.


HM303-6

2 Channels with deflection coefficients of 1mV/cm – 20 V/cm

Time Base: 0.2 s/cm – 100 ns/cm,

with X Magnification to 10 ns/cm

Low Noise Measuring Amplifiers with high pulse fidelity

and minimum overshoot

Triggering from 0 to 50 MHz from 5 mm signal level

(up to 100 MHz from 8 mm)

Up to 500,000 signal displays per second

in optimum analog quality

Yt, XY and component-test modes

3 5 M H z A n a lo g O s c i l lo s c o p e

H M 3 0 3 - 6

HM3036

Full screen display of

35 MHz sine wave signal

Line triggered composite

video signal

No signal distortion

resulting from overshoot


35 MHz Analog Oscilloscope HM303-6Valid at 23 °C after a 30 minute warm-up period

Vertical Deflection

Operating Modes: Channel I or II only

Channels I and II (alternate or chopped)

Sum or Difference of CH I and CH II

Invert: CH II

XY Mode: via CH I (X) and CH II (Y)

Bandwidth: 2 x 0 to 35 MHz (-3 dB)

Rise Time: ‹ 10 ns

Deflection Coefficients: 1-2-5 Sequence

1 mV/div. – 2 mV/div.: ± 5 % (Bandwidth 0 – 10 MHz (-3 dB))

5 mV/div. – 20 V/div.: ± 3 % (Bandwidth 0 – 35 MHz (-3 dB))

Variable (uncalibrated): › 2.5 : 1 to › 50 V/div.

Input Impedance: 1 MΩ II 20 pF

Input Coupling: DC, AC, GND (ground)

Max. Input Voltage: 400 V (DC + peak AC)

Triggering

Automatic (Peak to Peak): 20 Hz – 50 MHz (≥ 5 mm)

50 MHz – 100 MHz (≥ 8 mm)

Normal with Level Control: 0 – 50 MHz (≥ 5 mm)

50 MHz – 100 MHz (≥ 8 mm)

Trigger Indicator: LED

Slope: positive or negative

Sources: Channel I or II, CH I / CH II alternate

(≥ 8 mm), Line and External

Coupling: AC: 10 Hz – 100 MHz

DC: 0 – 100 MHz

LF: 0 – 1.5 kHz

Trigger Indicator: LED

External Trigger Signal: ≥ 0.3 Vpp (30 Hz – 50 MHz)

Active TV sync. separator: pos. and neg.

Horizontal Deflection

Time Base: 0.2 s/div. – 0.1 μs/div. (1-2-5 Sequence)

Accuracy: ± 3 %

Variabel (uncalibrated): › 2.5:1 to › 0.5 s/div.

X Magnification x 10: up to 10 ns/div.

Accuracy: ± 5 %

Hold-Off Time: variable to approx. 10 : 1

XY

Bandwidth X Amplifier: 0 – 2.5 MHz (-3 dB)

XY Phase shift ‹ 3°: ‹ 120 kHz

Component Tester

Test Voltage: approx. 7 Vrms (open circuit)

Test Current: max. 7 mArms (short-circuit)

Test Frequency: approx. 50 Hz

Test Connection: 2 banana jacks 4 mm Ø

One test circuit lead is grounded via protective earth (PE)

Miscellaneous

CRT: D14-363GY, 8 x 10 cm with internal graticule

Acceleration Voltage: approx. 2 kV

Trace Rotation: adjustable on front panel

Calibrator Signal (Square Wave): 0.2 V ± 1 %, ≈ 1 kHz/1 MHz (tr ‹ 4 ns)

Power Supply (Mains): 105 – 253 V, 50/60 Hz ± 10 %, CAT II

Power Consumption: approx. 36 Watt at 230 V/50 Hz

Ambient temperature: 0 °C...+ 40 °C

Safety class: Safety class I (EN61010-1)

Weight: approx. 5.4 kg

Dimensions (W x H x D): 285 x 125 x 380 mm

Accessories supplied: Line Cord, operator’s manual, 2 Probes 1:1 / 10:1 (HZ154)

HM303-6E/140408/ce · Subject to alterations · © HAMEG Instruments GmbH · ® Registered Trademark · DQS-certified in accordance with DIN EN ISO 9001:2000, Reg.-No.: DE-071040 QM

HAMEG Instruments GmbH · Industriestr. 6 · D-63533 Mainhausen · Tel +49 (0) 6182 800 0 · Fax +49 (0) 6182 800 100 · www.hameg.com · [email protected]

A Rohde & Schwarz Company

w w w . h a m e g . c o m

Specifi cations

+5 °C ... +40 °C


A

A

BB

C

C

D

D

E

E

T

F

PUkT

PUkT

PUk PUk PUk PUk PUk PUk

PUkT

PUkT PUkT

PUkT

HGOPFFD

PUkT

HGOFFD

PUOPFGkT

INPUT CHI

OPK

HJ

VBN

HJKL

INPUT CHI

OPK

HJ

VBN

HJKL

INPUT CHI

OPK

HJ

VBN

HJKL

PUkT

PUkT

PUOPFGkT PUOPFGkT

PUOPFGkT

PUOPFGkT

PUOPFGkT PUOPFGkT

PUOPFGkT PUOPFGkT

PUOPFGkT PUOPFGkT PUOPFGkT PUOPFGkT

HM507

PUOPFGkT PUOPFGkT PUOPFGkT PUOPFGkT PUOPFGkT PUOPFGkT

PUOPFGkT PUOPFGkT

PUOGkT

HAMEG

B

T

T

General information

Safe operation may be endangered if any of the following

was noticed:

– in case of visible damage.– in case loose parts were noticed– if it does not function any more.– after prolonged storage under unfavourable conditions (e.g.

like in the open or in moist atmosphere).– after any improper transport (e.g. insuffi cient packing not

conforming to the minimum standards of post, rail or transport company)

Proper operation

Please note: This instrument is only destined for use by personnel well instructed and familiar with the dangers of electrical measure-ments.

For safety reasons the oscilloscope may only be operated from mains outlets with safety ground connector. It is prohibited to separate the safety ground connection. The plug must be inserted prior to connecting any signals.

General information

Please check the instrument for mechanical damage or loose parts immediately after unpacking. In case of damage we advise to contact the sender. Do not operate.

List of symbols used

Consult the manual High voltage

STOP

Important note Ground

Positioning the instrument

As can be seen from the fi gures, the handle can be set into diffe-rent positions:A and B = carrying C = horizontal operating D and E = operating at different anglesF = handle removalT = shipping (handle unlocked)

STOP

Attention!

When changing the handle position, the instru-

ment must be placed so that it can not fall (e.g.

placed on a table). Then the handle locking knobs

must be simultaneously pulled outwards and

rotated to the required position. Without pulling

the locking knobs they will latch in into the next

locking position.

Handle mounting/dismounting

The handle can be removed by pulling it out further, depending on the instrument model in position B or F.

Safety

The instrument fulfi ls the VDE 0411 part 1 regulations for electrical measuring, control and laboratory instruments and was manufactured and tested accordingly. It left the factory in perfect safe condition. Hence it also corresponds to European Standard EN 61010-1 resp. International Standard IEC 1010-1. In order to maintain this condition and to ensure safe operation the user is required to observe the warnings and other directions for use in this manual. Housing, chassis as well as all measu-ring terminals are connected to safety ground of the mains. All accessible metal parts were tested against the mains with 200 VDC. The instrument conforms to safety class I.

The oscilloscope may only be operated from mains outlets with a safety ground connector. The plug has to be installed prior to con-necting any signals. It is prohibited to separate the safety ground connection.

Most electron tubes generate X-rays; the ion dose rate of this ins-trument remains well below the 36 pA/kg permitted by law.

In case safe operation may not be guaranteed do not use the ins-trument any more and lock it away in a secure place.


Type of fuse:

Size 5 x 20 mm; 250V~, C;IEC 127, Bl. III; DIN 41 662 (or DIN 41 571, Bl. 3).Cut off: slow blow (T) 0,8A.

General information

CAT I

This oscilloscope is destined for measurements in circuits not connected to the mains or only indirectly. Direct measurements, i.e. with a galvanic connection to circuits corresponding to the categories II, III, or IV are prohibited!

The measuring circuits are considered not connected to the mains if a suitable isolation transformer fulfi lling safety class II is used. Measurements on the mains are also possible if suitable probes like current probes are used which fulfi l the safety class II. The measurement category of such probes must be checked and observed.

Measurement categories

The measurement categories were derived corresponding to the distance from the power station and the transients to be expected hence. Transients are short, very fast voltage or current excursions which may be periodic or not.

Measurement CAT IV: Measurements close to the power station, e.g. on electricity meters

Measurement CAT III: Measurements in the interior of buildings (power distribution instal-lations, mains outlets, motors which are permanently installed).

Measurement CAT II: Measurements in circuits directly connected to the mains (house-hold appliances, power tools etc).

Measurement CAT I: Electronic instruments and circuits which contain circuit breakers resp. fuses.

Environment of use.

The oscilloscope is destined for operation in industrial, business, manufacturing, and living sites.

Environmental conditions

Operating ambient temperature: +5 °C to +40 °C. During transport or storage the temperature may be –20 °C to +70°C.

Please note that after exposure to such temperatures or in case of condensation proper time must be allowed until the instrument has reached the permissible temperature, resp. until the condensation has evaporated before it may be turned on! Ordinarily this will be the case after 2 hours. The oscilloscope is destined for use in clean and dry environments. Do not operate in dusty or chemically aggressive atmosphere or if there is danger of explosion.

The operating position may be any, however, suffi cient ventilation must be ensured (convection cooling). Prolonged operation requires the horizontal or inclined position.

STOP

Do not obstruct the ventilation holes!

Specifi cations are valid after a 30 minute warm-up period between 15 and 30 degr. C. Specifi cations without tolerances are average values.

Warranty and repair

HAMEG instruments are subjected to a strict quality control. Prior to leaving the factory, each instrument is burnt-in for 10 hours. By intermittent operation during this period almost all defects are detected. Following the burn-in, each instrument is tested for function and quality, the specifi cations are checked in all operating modes; the test gear is calibrated to national standards.

The warranty standards applicable are those of the country in which the instrument was sold. Reclamations should be directed to the dealer.

Only valid in EU countries

In order to speed reclamations customers in EU countries may also contact HAMEG directly. Also, after the warranty expired, the HAMEG service will be at your disposal for any repairs.

Return material authorization (RMA):

Prior to returning an instrument to HAMEG ask for a RMA number either by internet (http://www.hameg.com) or fax. If you do not have an original shipping carton, you may obtain one by calling the HAMEG service dept (++49 (0) 6182 800 500) or by sending an email to [email protected].

Maintenance

Clean the outer shell using a dust brush in regular intervals. Dirt can be removed from housing, handle, all metal and plastic parts using a cloth moistened with water and 1 % detergent. Greasy dirt may be removed with benzene (petroleum ether) or alcohol, there after wipe the surfaces with a dry cloth. Plastic parts should be treated with an antistatic solution destined for such parts. No fl uid may enter the instrument. Do not use other cleansing agents as they may adversely affect the plastic or lacquered surfaces.

Line voltage

The instrument has a wide range power supply from 105 to 253 V, 50 or 60 Hz ±10%. There is hence no line voltage selector.

The line fuse is accessible on the rear panel and part of the line input connector. Prior to exchanging a fuse the line cord must be pulled out. Exchange is only allowed if the fuse holder is undamaged, it can be taken out using a screwdriver put into the slot. The fuse can be pushed out of its holder and exchanged.

The holder with the new fuse can then be pushed back in place against the spring. It is prohibited to ”repair“ blown fuses or to bridge the fuse. Any damages incurred by such measures will void the warranty.

8 Subject to change without notice

Type of signal voltage

With the HM303-6, most repetitive signals in the frequencyrange up to at least 35MHz (-3dB) can be examined.

Sinewave signals of 50MHz are displayed with a height ofapprox. 50% (-6dB). However when examining square or pulsetype waveforms, attention must be paid to the harmoniccontent of such signals. The repetition frequency (fundamen-tal frequency) of the signal must therefore be significantlysmaller than the upper limit frequency of the vertical amplifier.Displaying composite signals can be difficult, especially if theycontain no repetitive higher amplitude content which can beused for triggering. This is the case with bursts, for instance. Toobtain a well-triggered display in this case, the assistance of thevariable holdoff and/or variable time control may be required.Television video signals are relatively easy to trigger using thebuilt-in TV-Sync-Separator (TV). For optional operation as aDC or AC voltage amplifier, the vertical amplifier input isprovided with a DC/AC switch. The DC position should only beused with a series-connected attenuator probe or at very lowfrequencies or if the measurement of the DC voltage contentof the signal is absolutely necessary.

When displaying very low frequency pulses, the flat tops may besloping with AC coupling of the vertical amplifier (AC limitfrequency approx. 1.6 Hz for 3dB). In this case, DC operation ispreferred, provided the signal voltage is not superimposed on atoo high DC level. Otherwise a capacitor of adequate capacitancemust be connected to the input of the vertical amplifier with DCcoupling. This capacitor must have a sufficiently high breakdownvoltage rating. DC coupling is also recommended for the displayof logic and pulse signals, especially if the pulse duty factorchanges constantly. Otherwise the display will move upwards ordownwards at each change. Pure direct voltages can only bemeasured with DC-coupling.

Amplitude Measurements

In general electrical engineering, alternating voltage datanormally refers to effective values (rms = root-mean-squarevalue). However, for signal magnitudes and voltage designationsin oscilloscope measurements, the peak-to-peak voltage (Vpp)value is applied. The latter corresponds to the real potentialdifference between the most positive and most negativepoints of a signal waveform.

If a sinusoidal waveform, displayed on the oscilloscope screen,is to be converted into an effective (rms) value, the resultingpeak-to-peak value must be divided by 2x√2 = 2.83. Conversely,it should be observed that sinusoidal voltages indicated in Vrms(Veff) have 2.83 times the potential difference in Vpp. Therelationship between the different voltage magnitudes can beseen from the following figure.

Voltage values of a sine curveVrms = effective value; Vp= simple peak or crest value;Vpp = peak-to-peak value; Vmom = momentary value.

The minimum signal voltage which must be applied to the Yinput for a trace of 1div. height is 1mVpp when the Y-MAG. x5pushbutton is depressed, the VOLTS/DIV. switch is set to5mV/div., and the vernier is set to CAL by turning the fineadjustment knob of the VOLTS/DIV. switch fully clockwise.However, smaller signals than this may also be displayed. Thedeflection coefficients on the input attenuators are indicatedin mV/div. or V/div. (peak-to-peak value).

The magnitude of the applied voltage is ascertained bymultiplying the selected deflection coefficient by the verticaldisplay height in div.

If an attenuator probe x10 is used, a further multiplication by afactor of 10 is required to ascertain the correct voltage value.

For exact amplitude measurements, the variable control on theattenuator switch must be set to its calibrated detent CAL.When turning the variable control ccw, the sensitivity will bereduced by a factor of 2.5.

Therefore every intermediate value is possible within the 1-2-5 sequence.

With direct connection to the vertical input, signals up to400Vpp may be displayed (attenuator set to 20V/div., variablecontrol to left stop).

With the designations

H = display height in div.,U = signal voltage in Vpp at the vertical input,D = deflection coefficient in V/div. at attenuator switch,

the required value can be calculated from the two givenquantities:

However, these three values are not freely selectable. Theyhave to be within the following limits (trigger threshold, accuracyof reading):

H between 0.5 and 8div., if possible 3.2 to 8div.,U between 0.5mVpp and 160Vpp,D between 1mV/div. and 20V/div. in 1-2-5 sequence.

Examples:Set deflection coefficient D = 50mV/div. 0.05V/div.,observed display height H = 4.6div.,required voltage U = 0.05·4.6 = 0.23Vpp.

Input voltage U = 5Vpp,set deflection coefficient D = 1V/div.,required display height H = 5:1 = 5div.

Signal voltage U = 230Vrms·2√2 = 651Vpp(voltage > 160Vpp, with probe 10:1: U = 65.1Vpp),desired display height H = min. 3.2div., max. 8div.,max. deflection coefficient D = 65.1:3.2 = 20.3V/div.,min. deflection coefficient D = 65.1:8 = 8.1V/div.,adjusted deflection coefficient D = 10V/div.

The input voltage must not exceed 400V, independentfrom the polarity. If an AC voltage which is superimposed ona DC voltage is applied, the maximum peak value of bothvoltages must not exceed + or –400V. So for AC voltages witha mean value of zero volt the maximum peak to peak valueis 800Vpp. If attenuator probes with higher limits are used,the probes limits are valid only if the oscilloscope is set to DCinput coupling.



If DC voltages are applied under AC input coupling conditionsthe oscilloscope maximum input voltage value remains 400V.The attenuator consists of a resistor in the probe and the 1MΩinput resistor of the oscilloscope, which are disabled by the ACinput coupling capacity when AC coupling is selected. This alsoapplies to DC voltages with superimposed AC voltages. It alsomust be noted that due to the capacitive resistance of the ACinput coupling capacitor, the attenuation ratio depends on thesignal frequency. For sinewave signals with frequencies higherthan 40Hz this influence is negligible.

In the GD (ground coupling) setting, the signal path is interrupteddirectly beyond the input. This causes the attenuator to bedisabled again, but now for both DC and AC voltages.

With the above listed exceptions HAMEG 10:1 probes can beused for DC measurements up to 600V or AC voltages (with amean value of zero volt) of 1200Vpp. The 100:1 probe HZ53allows for 1200V DC or 2400Vpp for AC.

It should be noted that its ACpeak value is derated at higherfrequencies. If a normal x10 probe is used to measure highvoltages there is the risk that the compensation trimmerbridging the attenuator series resistor will break down causingdamage to the input of the oscilloscope. However, if forexample only the residual ripple of a high voltage is to bedisplayed on the oscilloscope, a normal x10 probe is sufficient.In this case, an appropriate high voltage capacitor (approx. 22-68nF) must be connected in series with the input tip of theprobe.

Total value of input voltage

The dotted line shows a voltage alternating at zero volt level.If superimposed on a DC voltage, the addition of the positivepeak and the DC voltage results in the max. voltage (DC +ACpeak).

With Y-POS. control (input coupling to GD) it is possible to usea horizontal graticule line as reference line for groundpotential before the measurement. It can lie below or abovethe horizontal central line according to whether positive and/or negative deviations from the ground potential are to bemeasured.

Time Measurements

As a rule, most signals to be displayed are periodically repeatingprocesses, also called periods. The number of periods persecond is the repetition frequency. Depending on the timebase setting of the TIME/DIV. switch, one or several signalperiods or only a part of a period can be displayed. The timecoefficients are stated in s/div., ms/div. and µs/div. on theTIME/DIV.-switch. The scale is accordingly divided into threefields.

The duration of a signal period or a part of it is determined bymultiplying the relevant time (horizontal distance in div.) by thetime coefficient set on the TIME/DIV.-switch.

The variable time control (identified with an arrow knobcap) must be in its calibrated position CAL. (arrow pointinghorizontally to the right).

With the designations

L = displayed wave length in div. of one period,T = time in seconds for one period,F = recurrence frequency in Hz of the signal,Tc = time coefficient in s/div. on time base switch and

the relation F = 1/T, the following equations can be stated:

With depressed X-MAG. (x10) pushbutton the Tc value must bedivided by 10.

However, these four values are not freely selectable. Theyhave to be within the following limits:

L between 0.2 and 10div., if possible 4 to 10div.,T between 0.01µs and 2s,F between 0.5Hz and 30MHz,Tc between 0.1µs/div. and 0.2s/div. in 1-2-5 sequence

(with X-MAG. (x10) in out position), andTc between 10ns/div. and 20ms/div. in 1-2-5 sequence

(with pushed X-MAG. (x10) pushbutton).

Examples:Displayed wavelength L = 7div.,set time coefficient Tc = 0.1µs/div.,required period T = 7x0.1x10-6 = 0.7µsrequired rec. freq. F = 1:(0.7x10-6) = 1.428MHz.

Signal period T = 1s,set time coefficient Tc = 0.2s/div.,required wavelength L = 1:0.2 = 5div..

Displayed ripple wavelength L = 1div.,set time coefficient Tc = 10ms/div.,required ripple freq. F = 1:(1x10x10-3) = 100Hz.

TV-line frequency F = 15625Hz,set time coefficient Tc = 10µs/div.,required wavelength L = 1:(15 625x10-5) = 6.4div..

Sine wavelength L = min. 4div., max. 10div.,Frequency F = 1kHz,max. time coefficient Tc = 1:(4x103) = 0.25ms/div.,min. time coefficient Tc = 1:(10x103) = 0.1ms/div.,set time coefficient Tc = 0.2ms/div.,required wavelength L = 1:(103x0.2x10-3) = 5div.

Displayed wavelength L = 0.8div.,set time coefficient Tc = 0.5µs/div.,pressed X-MAG. (x10) button: Tc = 0.05µs/div.,required rec. freq. F = 1:(0.8x0.05x10-6) = 25MHz,required period T = 1:(25x10-6) = 40ns.

If the time is relatively short as compared with the completesignal period, an expanded time scale should always beapplied (X-MAG. x10 button pressed). In this case, theascertained time values have to be divided by 10. The timeinterval of interest can be shifted to the screen center usingthe X-POS. control.



When investigating pulse or square waveforms, the criticalfeature is the risetime of the voltage step. To ensure thattransients, ramp-offs, and bandwidth limits do not unduly influencethe measuring accuracy, the risetime is generally measuredbetween 10% and 90% of the vertical pulse height. Formeasurement adjust the Y attenuator switch with its variablecontrol together with the Y-POS. control so that the pulse heightis precisely aligned with the 0% and 100% lines of the internalgraticule. The 10% and 90% points of the signal will now coincidewith the 10% and 90% graticule lines. The risetime is given bythe product of the horizontal distance in div. between thesetwo coincidence points and the time coefficient setting. If Xx10 magnification is used, this product must be divided by 10. Thefall time of a pulse can also be measured by using this method.

The following figure shows correct positioning of the oscilloscopetrace for accurate risetime measurement.

With a time coefficient of 0.2µs/div. and pushed X-MAG x10button the example shown in the above figure results in ameasured total risetime of

ttot = 1.6div x 0.2µs/div. / 10 = 32ns

When very fast risetimes are being measured, the risetimes ofthe oscilloscope amplifier and of the attenuator probe has to bededucted from the measured time value. The risetime of the

signal can be calculated using the following formula.

In this ttot is the total measured risetime, tosc is the risetime of theoscilloscope amplifier (approx. 10ns), and tp the risetime of theprobe (e.g. = 2ns). If ttot is greater than 100ns, then ttot can betaken as the risetime of the pulse, and calculation is unnecessary.

Calculation of the example in the figure above results in a signalrisetime

tr= √322 - 102 - 22 = 30,3ns

The measurement of the rise or fall time is not limited to thetrace dimensions shown in the above diagram. It is onlyparticularly simple in this way. In principle it is possible tomeasure in any display position and at any signal amplitude. Itis only important that the full height of the signal edge ofinterest is visible in its full length at not too great steepness andthat the horizontal distance at 10% and 90% of the amplitudeis measured. If the edge shows rounding or overshooting, the100% should not be related to the peak values but to the meanpulse heights. Breaks or peaks (glitches) next to the edge arealso not taken into account. With very severe transientdistortions, the rise and fall time measurement has little meaning.For amplifiers with approximately constant group delay(therefore good pulse transmission performance) the followingnumerical relationship between rise time tr (in ns) and bandwidthB (in MHz) applies:

Connection of Test Signal

Caution:When connecting unknown signals to the oscilloscopeinput, always use automatic triggering and set the DC-ACinput coupling switch to AC. The attenuator switch shouldinitially be set to 20V/div.

Sometimes the trace will disappear after an input signal hasbeen applied. The attenuator switch must then be turned backto the left, until the vertical signal height is only 3-8div. Witha signal amplitude greater than 160Vpp, an attenuator probemust be inserted before the vertical input. If, after applyingthe signal, the trace is nearly blanked, the period of the signalis probably substantially longer than the set value on theTIME/DIV. switch. It should be turned to the left to anadequately larger time coefficient.

The signal to be displayed can be connected directly to the Y-input of the oscilloscope with a shielded test cable such as HZ32 or HZ 34, or reduced through a x10 or x100 attenuatorprobe. The use of test cables with high impedance circuits isonly recommended for relatively low frequencies (up to approx.50kHz). For higher frequencies, the signal source must be oflow impedance, i.e. matched to the characteristic resistanceof the cable (as a rule 50Ω). Especially when transmittingsquare and pulse signals, a resistor equal to the characteristicimpedance of the cable must also be connected across thecable directly at the Y-input of the oscilloscope. When usinga 50Ω cable such as the HZ 34, a 50Ω through termination typeHZ22 is available from HAMEG.

When transmitting square signals with short rise times, transientphenomena on the edges and top of the signal may becomevisible if the correct termination is not used. A terminatingresistance is sometimes recommended with sine signals aswell. Certain amplifiers, generators or their attenuators maintainthe nominal output voltage independent of frequency only iftheir connection cable is terminated with the prescribedresistance. Here it must be noted that the terminating resistorHZ22 will only dissipate a maximum of 2 Watts. This power isreached with 10 Vrms or at 28.3 Vpp with sine signal.

If a x10 or x100 attenuator probe is used, no termination isnecessary. In this case, the connecting cable is matcheddirectly to the high impedance input of the oscilloscope. Whenusing attenuators probes, even high internal impedance sourcesare only slightly loaded (approx. 10MΩ II 16pF or 100MΩ II 9pFwith HZ53). Therefore, if the voltage loss due to the attenuationof the probe can be compensated by a higher amplitude setting,the probe should always be used. The series impedance of theprobe provides a certain amount of protection for the input ofthe vertical amplifier. Because of their separate manufacture,all attenuator probes are only partially compensated, thereforeaccurate compensation must be performed on the oscilloscope(see ”Probe compensation” ).

Standard attenuator probes on the oscilloscope normallyreduce its bandwidth and increase the rise time. In all caseswhere the oscilloscope bandwidth must be fully utilized (e.g.for pulses with steep edges) we strongly advise using theprobes HZ51 (x10) HZ52 (x10 HF) and HZ54 (x1 and x10). Thiscan save the purchase of an oscilloscope with larger bandwidthand has the advantage that defective components can beordered from HAMEG and replaced by oneself. The probesmentioned have a HF-calibration in addition to low frequencycalibration adjustment. Thus a group delay correction to the



upper limit frequency of the oscilloscope is possible with theaid of an 1MHz calibrator, e.g. HZ60.

In fact the bandwidth and rise time of the oscilloscope are notnoticeably changed with these probe types and the waveformreproduction fidelity can even be improved because the probecan be matched to the oscilloscopes individual pulse response.

If a x10 or x100 attenuator probe is used, DC inputcoupling must always be used at voltages above 400V.With AC coupling of low frequency signals, the attenuation isno longer independent of frequency, pulses can show pulsetilts. Direct voltages are suppressed but load the oscilloscopeinput coupling capacitor concerned. Its voltage rating is max.400V (DC + peak AC). DC input coupling is therefore of quitespecial importance with a x100 attenuation probe whichusually has a voltage rating of max. 1200 V (DC + peak AC). Acapacitor of corresponding capacitance and voltage ratingmay be connected in series with the attenuator probe inputfor blocking DC voltage (e.g. for hum voltage measurement).

With all attenuator probes, the maximum AC input voltagemust be derated with frequency usually above 20kHz.Therefore the derating curve of the attenuator probe typeconcerned must be taken into account.

The selection of the ground point on the test object is importantwhen displaying small signal voltages. It should always be asclose as possible to the measuring point. If this is not done,serious signal distortion may result from spurious currentsthrough the ground leads or chassis parts. The ground leads onattenuator probes are also particularly critical. They should beas short and thick as possible. When the attenuator probe isconnected to a BNC-socket, a BNC-adapter, which is oftensupplied as probe accessory, should be used. In this wayground and matching problems are eliminated.

Hum or interference appearing in the measuring circuit(especially when a small deflection coefficient is used) ispossibly caused by multiple grounding because equalizingcurrents can flow in the shielding of the test cables (voltagedrop between the protective conductor connections, causedby external equipment connected to the mains/line, e.g.signal generators with interference protection capacitors).

First Time Operation

Before applying power to the oscilloscope it is recommendedthat the following simple procedures are performed:

• Check that all pushbuttons are in the out position, i.e.released.

• Rotate the variable controls with arrows, i.e. TIME/DIV.variable control, CH I and CH II attenuator variable controls,and HOLDOFF control to their calibrated detent.

• Set all controls with marker lines to their midrange position(marker lines pointing vertically).

• The TRIG. MODE selector switch should be set to theposition uppermost (AC).

• Both GD input coupling pushbutton switches for CH I andCH II should be set to the GD position.

Switch on the oscilloscope by depressing the red POWERpushbutton. An LED will illuminate to indicate working order.The trace, displaying one baseline, should be visible after ashort warm-up period of approx. 10 seconds. Adjust Y-POS.Iand X-POS. controls to center the baseline. Adjust INTENS(intensity) and FOCUS controls for medium brightness andoptimum sharpness of the trace. The oscilloscope is nowready for use.

If only a spot appears (CAUTION! CRT phosphor can be damaged),reduce the intensity immediately and check that the XYpushbutton is in the released (out) position. If the trace is notvisible, check the correct positions of all knobs and switches(particularly AT/NM button in out position).

To obtain the maximum life from the cathode-ray tube, theminimum intensity setting necessary for the measurement inhand and the ambient light conditions should be used.

Particular care is required when a single spot is displayed, asa very high intensity setting may cause damage to the fluorescentscreen of the CRT. Switching the oscilloscope off and on at shortintervals stresses the cathode of the CRT and should thereforebe avoided.

The instrument is so designed that even incorrect operation willnot cause serious damage. The pushbuttons control only minorfunctions, and it is recommended that before commencementof operation all pushbuttons are in the ”out” position. After thisthe pushbuttons can be operated depending upon the mode ofoperation required.

Trace Rotation TR

In spite of Mumetal-shielding of the CRT, effects of the earth’smagnetic field on the horizontal trace position cannot becompletely avoided. This is dependent upon the orientation ofthe oscilloscope on the place of work. A centerd trace may notalign exactly with the horizontal center line of the graticule. A fewdegrees of misalignment can be corrected by a potentiometeraccessible through an opening on the front panel marked TRACEROTATION.

Probe compensation and use

To display an undistorted waveform on an oscilloscope, theprobe must be matched to the individual input impedance of thevertical amplifier.

For this purpose a square wave signal with a very fast rise timeand minimum overshoot should be used, as the sinusoidalcontents cover a wide frequency range. The frequency accuracyand the pulse duty factor are not of such importance.

The built-in calibration generator provides a square wave signalwith a very fast risetime (<4ns), and switch-selectable frequenciesof approx. 1kHz and 1MHz from the output socket below the CRTscreen.

This signal should not be used for frequency calibration!

The output provides 0.2Vpp 1% (tr <4ns) for x10 probes. Whenthe Y deflection coefficient is set to 5mV/div, the calibrationvoltage corresponds to a vertical display of 4 divisions (x10probe).

The output sockets have an internal diameter of 4.9mm toaccommodate the internationally accepted shielding tubediameter of modern Probes and F-series slimline probes. Onlythis type of construction ensures the extremely short groundconnections which are essential for an undistorted waveformreproduction of non-sinusoidal high frequency signals.

Adjustment at 1kHz

The C-trimmer adjustment (low frequency) compensates thecapacitive loading on the oscilloscope input (approx. 20 pF forthe HM303-6). By this adjustment, the capacitive divisionassumes the same ratio as the ohmic voltage divider to

First Time Operation

ensure the same division ratio for high and low frequencies,


as for DC. (For x1 probes or switchable probes set to x1, thisadjustment is neither required nor possible). A baseline exactlyparallel to the horizontal graticule lines is a major condition foraccurate probe adjustments. (See also “Trace rotation”).

Connect the probes (Types HZ51, 52, 54, or HZ36) to the CH Iinput. All pushbuttons should be released (in the out position).Set input coupling to DC, the attenuator to 5 mV/div., and TIME/DIV. switch to 0.2 ms/div., and all variable controls to CAL.position. Plug the probe tip into the calibrator output socket.

Approximately 2 complete waveform periods are displayed onthe CRT screen. Now the compensation trimmer has to beadjusted. The location of the low frequency compensationtrimmer can be found in the probe information sheet. Adjustthe trimmer with the insulating screw driver provided until thetops of the square wave signal are exactly parallel to thehorizontal graticule lines (see 1 kHz diagram). The signalheight should then be 4 div. 0.16div. (= 4 % (oscilloscope 3%and probe 1%) ). During this adjustment, the signal edges willremain invisible.

Adjustment at 1MHz

Probes HZ51, 52 and 54 can also be HF-compensated. Theyincorporate resonance de-emphasing networks (R-trimmer inconjunction with capacitors) which permit probe compensationin the range of the upper frequency limit of the verticaloscilloscope amplifier. Only this compensative adjustmentensures optimum utilisation of the full bandwidth, togetherwith constant group delay at the high frequency end, therebyreducing characteristic transient distortion near the leadingedge (e.g. overshoot, rounding, ringing, holes or bumps) to anabsolute minimum.

Using the probes HZ51, 52 and 54, the full bandwidth of theHM303-6 can be utilized without risk of unwanted waveformdistortion.

Prerequisite for this HF compensation is a square wavegenerator with fast risetime (typically 4 ns), and low outputimpedance (approx. 50Ω), providing 0.2V at a frequency ofapprox. 1MHz. The calibrator output of the HM303-6 meetsthese requirements when the CAL. pushbutton is depressed.

Connect the probe to CH I input. Depress the CAL. pushbuttonfor 1MHz. All other pushbuttons should be released (outposition). Set the CH I input coupling to DC, attenuator switchto 5mV/div, and TIME/DIV. switch to 0.2µs/div. Set allvariable controls to CAL. position.

Insert the probe tip into the output socket. A waveform will bedisplayed on the CRT screen, with leading and trailing edgesclearly visible. For the HF-adjustment now to be performed, itwill be necessary to observe the rising edge as well as theupper left corner of the pulse top. The location of the highfrequency compensation trimmer(s) can also be found in theprobe information sheet. These R-trimmer(s) have to beadjusted such that the beginning of the pulse is as straight aspossible. Overshoot or excessive rounding are unacceptable.

The adjustment is relatively easy if only one adjusting point ispresent. In case of several adjusting points the adjustment is

slightly more difficult, but causes a better result. The risingedge should be as steep as possible, with a pulse top remainingas straight and horizontal as possible.

After completion of the HF-adjustment, the signal amplitudedisplayed on the CRT screen should have the same value asduring the 1kHz adjustment.

Probes other than those mentioned above, normally have alarger tip diameter and may not fit into the calibrator outputs.Whilst it is not difficult for an experienced operator to build asuitable adapter, it should be pointed out that most of theseprobes have a slower risetime with the effect that the totalbandwidth of scope together with probe may fall far belowthat of the HM303-6. Furthermore, the HF-adjustment featureis nearly always missing so that waveform distortion can notbe entirely excluded.

The adjustment sequence must be followed in the orderdescribed, i.e. first at 1kHz, then at 1MHz. The calibratorfrequencies should not be used for time base calibration. Thepulse duty cycle deviates from 1:1 ratio. Prerequisites forprecise and easy probe adjustments, as well as checks ofdeflection coefficients, are straight horizontal pulse tops,calibrated pulse amplitude, and zero-potential at the pulsebase. Frequency and duty cycle are relatively uncritical. Forinterpretation of transient response, fast pulse risetimes andlow-impedance generator outputs are of particular importance.Providing these essential features, as well as switch-selectableoutput-frequencies, the calibrator of the HM303-6 can, undercertain conditions, replace expensive squarewave generatorswhen testing or compensating wideband-attenuators or -amplifiers. In such a case, the input of an appropriate circuit willbe connected to the CALIBRATOR-output via a suitable probe.

The voltage provided at a high-impedance input (1MΩ II 15-30pF) will correspond to the division ratio of the probe used(x10 = 20mVpp). Suitable probes are HZ51, 52, and 54.

Operating modes ofthe vertical amplifiers

The vertical amplifier is set to the desired operating mode byusing the 3 pushbuttons (CH I/II, DUAL and ADD) underneaththe attenuator switches. For Mono mode all 3 buttons must bein their released positions; only channel I can then be operated.The button CH I/II-TRIG.I/II must be depressed in mono modefor Channel II. The internal triggering is simultaneously switchedover to Channel II with this button. If the DUAL button isdepressed, both channels are working. Two signals can bedisplayed together in this button position (alternate mode) if thetime-base setting and the repetition frequency of the signal aresuited. This mode is not suitable for displaying very slow-running processes. The display then flickers too much or itappears to jump. If the ADD button is depressed in addition toDUAL, both channels are switched over constantly at a highfrequency within a sweep period (CHOP mode). Low frequencysignals below 1kHz, or with periods longer than 1ms arethen also displayed without flicker. CHOP mode is notrecommended for signals with higher repetition frequencies.

If only the ADD button is depressed, the signals of bothchannels are algebraically added (+I ±II). Whether the resulting

Operating modes of the vertical amplifiers


display shows the sum or difference is dependent on thephase relationship or the polarity of the signals and on thepositions of the INV. (invert) button.

In-phase input voltages:INV. button released = sum.INV. button depressed = difference.

Antiphase input voltages:INV. button released = difference.INV. button depressed = sum.

In the ADD mode the vertical display position is dependentupon the Y-POS. setting of both channels. The same attenuatorswitch position is normally used for both channels withalgebraic addition.

Please note that the Y-POS. settings are added too but are notaffected by the INV. pushbutton.

Differential measurement techniques allow direct measure-ment of the voltage drop across floating components (bothends above ground). Two identical probes should be used forboth vertical inputs. In order to avoid ground loops, use aseparate ground connection and do not use the probe groundleads or cable shields.

X-Y Operation

For X-Y operation, the pushbutton underneath the TIME/DIV.-knob marked XY must be depressed. The X signal is thenderived from the INPUT CH I (X). The calibration of the Xsignal during X-Y operation is determined by the settingof the Channel I input attenuator and variable control.This means that the sensitivity ranges and input impedancesare identical for both the X and Y axes. However, the Y-POS.Icontrol is disconnected in this mode. Its function is taken overby the X-POS. control. It is important to note that the X-MAG.x10 facility, normally used for expanding the sweep, isinoperative in the X-Y mode.

The bandwidth of the X amplifier, is lower than the Y amplifierand the phase angle which increases with higher frequencies,must be taken into account (please note ”Specifications”).

The inversion of the Y-input signal (CH II) using the INV.button is possible.

Lissajous figures can be displayed in the X-Y mode for certainmeasuring tasks:

- Comparing two signals of different frequency or bringingone frequency up to the frequency of the other signal. Thisalso applies for whole number multiples or fractions of theone signal frequency.

- Phase comparison between two signals of the samefrequency.

Phase comparison with Lissajous figures

The following diagrams show two sine signals of the samefrequency and amplitude with different phase angles.

Calculation of the phase angle or the phase shift between theX and Y input voltages (after measuring the distances a and bon the screen) is quite simple with the following formula, anda pocket calculator with trigonometric functions. Apart fromthe reading accuracy, the signal height has no influence on theresult.

The following must be noted here:

- Because of the periodic nature of the trigonometricfunctions, the calculation should be limited to angles ≤90°.However here is the advantage of the method.

- Do not use a too high test frequency. The phase shift of thetwo oscilloscope amplifiers of the HM303-6 in the X-Ymode can exceed an angle of 3° above120 kHz.

- It cannot be seen as a matter of course from the screendisplay if the test voltage leads or lags the referencevoltage. A CR network before the test voltage input of theoscilloscope can help here. The 1 MΩ input resistance canequally serve as R here, so that only a suitable capacitor Cneeds to be connected in series. If the aperture width ofthe ellipse is increased (compared with C short-circuited),then the test voltage leads the reference voltage and viceversa. This applies only in the region up to 90° phase shift.Therefore C should be sufficiently large and produce onlya relatively small just observable phase shift.

Should both input voltages be missing or fail in the X-Y mode,a very bright light dot is displayed on the screen. This dot canburn into the phosphor at a too high brightness setting(INTENS knob) which causes either a lasting loss of brightness,or in the extreme case, complete destruction of the phosphorat this point.

Phase difference measurementin DUAL mode

A larger phase difference between two input signals of thesame frequency and shape can be measured very simply onthe screen in Dual mode (DUAL button depressed). The timebase should be triggered by the reference signal (phaseposition 0).

The other signal can then have a leading or lagging phaseangle. Alternate mode should be selected for frequencies ≥1kHz; the Chop mode is more suitable for frequencies <1 kHz(less flickering).

For greatest accuracy adjust not much more than one periodand approximately the same height of both signals on thescreen. The variable controls for amplitude and time base andthe LEVEL knob can also be used for this adjustment withoutinfluence on the result.

Both base lines are set onto the horizontal graticule center linewith the Y-POS knobs before the measurement. With sinusoidalsignals, observe the zero (crossover point) transitions; the sinepeaks are less accurate. If a sine signal is noticeably distortedby even harmonics, or if a D.C. voltage is present, AC couplingis recommended for both channels. If it is a question of pulsesof the same shape, read off at steep edges.

Operating modes of the vertical amplifiers


Phase difference measurement in DUAL mode

t = horizontal spacing of the zero transitions in div.T = horizontal spacing for one period in div.

In the example illustrated, t = 3div. and T = 10div. The phasedifference in degrees is calculated from

or expressed in radians

Relatively small phase angles at not too high frequencies can bemeasured more accurately in the X-Y mode with Lissajous figures.

Measurement of an amplitude modulation

The momentary amplitude u at time t of a HF-carrier voltage, whichis amplitude modulated without distortion by a sinusoidal AFvoltage, is in accordance with the equation

where

UT = unmodulated carrier amplitudeΩΩΩΩΩ = 2πππππF = angular carrier frequencyωωωωω = 2πππππf = modulation angular frequencym = modulation factor (i.a. ≤ 1 100%).

The lower side frequency F-f and the upper side frequency F+f arisebecause of the modulation apart from the carrier frequency F.Figure 1.

Amplitude and frequency spectrum for AM display (m = 50%)

The display of the amplitude-modulated HF oscillation can beevaluated with the oscilloscope provided the frequency spectrumis inside the oscilloscope bandwidth. The time base is set so thatseveral cycles of the modulation frequency are visible. Strictlyspeaking, triggering should be external with modulation frequency(from the AF generator or a demodulator). However, internaltriggering is frequently possible with normal triggering (AT/NMbutton depressed) using a suitable LEVEL setting and possiblyalso using the time variable adjustment.

Oscilloscope setting for a signal according to figure 2:Depress no buttons.Y: CH I; 20mV/div.; AC.TIME/DIV.: 0.2ms/div.

Triggering: NM (NORMAL);with LEVEL-setting;internal (or external) triggering.

Figure 2.Amplitude modulated oscillation:F = 1 MHz; f = 1 kHz;m = 50 %; UT = 28.3 mVrms.

If the two values a and b are read from the screen, themodulation factor is calculated from

where

a = UT (1+m) and b = U

T (1-m).

The variable controls for amplitude and time can be set arbitrarilyin the modulation factor measurement. Their position does notinfluence the result.

Triggering and time base

Time related amplitude changes on a measuring signal (ACvoltage) are displayable in Yt-mode. In this mode the signalvoltage deflects the beam in vertical direction while the timebase generator moves the beam from the left to the right of thescreen (time deflection).

Normally there are periodically repeating waveforms to bedisplayed. Therefore the time base must repeat the timedeflection periodically too. To produce a stationary display, thetime base must only be triggered if the signal height and slopecondition coincide with the former time base start conditions.A DC voltage signal can not be triggered as it is a constant signalwith no slope.

Triggering can be performed by the measuring signal itself(internal triggering) or by an external supplied but synchronousvoltage (external triggering).

The trigger voltage should have a certain minimum amplitude.This value is called the trigger threshold. It is measured with asine signal. When the trigger voltage is taken internally from thetest signal, the trigger threshold can be stated as verticaldisplay height in div., through which the time base generatorstarts, the display is stable, and the trigger LED lights.

The internal trigger threshold of the HM303-6 is given as £0.5div. When the trigger voltage is externally supplied, it can bemeasured in Vpp at the TRIG. EXT. socket. Normally, the triggerthreshold may be exceeded up to a maximum factor of 20.

The HM303-6 has two trigger modes, which are characterizedin the following.

Operating modes of the vertical amplifiers Triggering and time base


Automatic Peak (value) - Triggering

If the AT/NM pushbutton is in the out position AT, the sweepgenerator is running without test signal or external trigger voltage.A base line is always displayed even without a signal applied.

In automatic trigger mode the sweep generator can run withouttest signal or external trigger voltage. A base line will always bedisplayed even with no signal. With an applied AC signal thepeak value triggering enables the user to select the voltagepoint on the trigger signal (trigger point), by the adjustment ofthe trigger LEVEL control. The control range depends on thepeak to peak value of the signal. This trigger mode is thereforecalled Automatic Peak (Value)- Triggering. Operation of thescope needs only correct amplitude and time base settings, fora constantly visible trace. Automatic mode is recommended forall uncomplicated measuring tasks. However, automatictriggering is also the appropriate operation mode for the “entry”into difficult measuring problems, e.g. when the test signal isunknown relating to amplitude, frequency or shape. Presentingof all parameters is now possible with automatic triggering; thechange to normal triggering can follow thereafter.

The automatic triggering works above 20Hz. The failure ofautomatic triggering at frequencies below 20Hz is abrupt.However, it is not signified by the trigger indicator LED this is stillblinking. Break down of triggering is best recognizable at the leftscreen edge (the start of the trace in differing display height).

The automatic peak (value) triggering operates over all variationsor fluctuations of the test signal above 20Hz. However, if thepulse duty factor of a square-wave signal exceeds a ratio of100:1, switching over to normal triggering will be necessary.Automatic triggering is practicable with internal and externaltrigger voltage.

Normal Triggering

With normal triggering (AT/NM button depressed) the sweepcan be started by AC signals within the frequency rangedefined by the TRIG. MODE (trigger coupling) setting.

In the absence of an adequate trigger signal or when the triggercontrols (particularly the LEVEL control) are misadjusted, notrace is visible, i.e. the screen blanked completely.

When using the internal normal triggering mode, it is possibleto trigger at any amplitude point of a signal edge, even with verycomplex signal shapes, by adjusting the LEVEL control. Itsadjusting range is directly dependent on the display height,which should be at least 0.5div. If it is smaller than 1div., theLEVEL adjustment needs to be operated with a sensitivetouch. In the external normal triggering mode, the same appliesto approx. 0.3Vpp external trigger voltage amplitude.

Other measures for triggering of very complex signals are theuse of the time base variable control and HOLDOFF time control,hereinafter mentioned.

Slope

The time base generator can be started by a rising or falling edgeof the test signal. This is valid with automatic and with normaltriggering. The selected slope is set with the SLOPE ( )pushbutton. The / sign (button released) means an edge, whichis coming from a negative potential and rising to a positivepotential. That has nothing to do with zero or ground potentialand absolute voltage values. The positive slope may also lie in anegative part of a signal. A falling edge ( \ sign) triggers, when theSLOPE ( ) pushbutton is depressed.

However the trigger point may be varied within certain limits onthe chosen edge using the LEVEL control. The slope direction isalways related to the input signal and the non inverted display..Trigger coupling

The coupling mode and accordingly the frequency range of thetrigger signal can be changed using the TRIG. MODE selectorswitch.

AC: Trigger range <20Hz to 100MHz.This is the most frequently used trigger mode. The triggerthreshold is increasing below 20Hz and above 100MHz.

DC: Trigger range DC to 100MHz.DC triggering is recommended, if the signal is to be triggeredwith quite slow processes or if pulse signals with constantlychanging pulse duty factors have to be displayed.

With DC- or LF-trigger coupling, always work with normaltriggering and LEVEL adjustment.

LF: Trigger range DC to 1.5kHz (low-pass filter).The LF position is often more suited for low-frequencysignals than the DC position, because the (white) noise inthe trigger voltage is strongly suppressed. So jitter ordouble-triggering of complex signals is avoidable or at leastreduced, in particular with very low input voltages. Thetrigger threshold increases above 1.5kHz.

TV: The built-in active TV-Sync-Separator enables theseparation of sync pulses from the video signal. Evendistorted video signals are triggered and displayed in astable manner.

Video signals are triggered in the automatic mode. Theinternal triggering is virtually independent of the displayheight, but the sync pulse must exceed 0.5div. height. ForTV sync pulse separation the TRIG. MODE switch must beset to TV. The TIME/DIV.-switch selects between field(0.2s/div. - 1ms/div.) and line (0.5ms/div. - 0.1µs/div.).

The slope of the leading edge of the synchronization pulse iscritical for the SLOPE pushbutton setting. If the displayed syncpulses are above the picture (field) contents, then the SLOPEpushbutton ( ) must be in / position (out). In the case of syncpulses below the field/line, the leading edge is negative and theSLOPE pushbutton must therefore be depressed (to ”\”). Sincethe INV. (invert) function may cause a misleading display, it mustnot be activated until after correct triggering is achieved.On the 2ms/div setting field TV triggering is selected and 1 fieldis visible if a 50 fields/s signal is applied. If the holdoff control isin fully ccw position, it triggers without line interlacing affectscaused by the consecutive field. More details in the video signalbecome visible if the X-MAG. x10 pushbutton is depressed (in).The X-POS. control allows to display any part of the expandedsignal. The influence of the integrating network which forms atrigger pulse from the vertical sync pulses may become visibleunder certain conditions.

Disconnecting the trigger circuit (e.g. by rapidly pressing andreleasing the TRIG. EXT. button) can result in triggering theconsecutive (odd or even) field.

On the 10µs/div setting line TV triggering is selected and approx.1½ lines are visible. Those lines originate randomly from the oddand even fields.

The sync-separator-circuit also operates with external triggering.It is important that the voltage range (0.3Vpp to 3Vpp) for external



triggering should be noted. Again the correct slope setting iscritical, because the external trigger signal may not have thesame polarity or pulse edge as the test signal. This can bechecked, if the external trigger voltage itself is displayed first(with internal triggering).

In most cases, the composite video signal has a high DCcontent. With constant video information (e.g. test pattern orcolor bar generator), the DC content can be suppressed easilyby AC input coupling of the oscilloscope amplifier. With achanging picture content (e.g. normal program), DC inputcoupling is recommended, because the display varies itsvertical position on screen with AC input coupling at eachchange of the picture content. The DC content can becompensated using the Y-POS. control so that the signaldisplay lies in the graticule area. Then the composite videosignal should not exceed a vertical height of 6div.

Line triggering (~)

A voltage originating from mains/line (50 to 60Hz) is used fortriggering purposes if the AT/NM and ALT pushbuttons aredepressed ( ~ symbol). When the AT/NM pushbutton isdepressed the instrument is automatically set to normaltriggering.

This trigger mode is independent of amplitude and frequencyof the Y signal and is recommended for all mains/linesynchronous signals. This also applies within certain limits towhole number multiples or fractions of the line frequency.Line triggering can also be useful to display signals below thetrigger threshold (less than 0.5div). It is therefore particularlysuitable for measuring small ripple voltages of mains/linerectifiers or stray magnetic field in a circuit. In this triggermode the SLOPE pushbutton selects the positive or negativeportion of the line sinewave. The LEVEL control is operativefor trigger point adjustment.

Magnetic leakage (e.g. from a power transformer) can beinvestigated for direction and amplitude using a search orpick-up coil. The coil should be wound on a small former witha maximum of turns of a thin lacquered wire and connected toa BNC connector (for scope input) via a shielded cable.Between cable and BNC center conductor a resistor of at least100Ω should be series-connected (RF decoupling). Often it isadvisable to shield statically the surface of the coil. However,no shorted turns are permissible. Maximum, minimum, anddirection to the magnetic source are detectable at themeasuring point by turning and shifting the coil.

Alternate triggering

With alternate triggering (ALT button depressed) it is possibleto trigger two signals which are different in frequency(asynchronous). In this case the oscilloscope must be operatedin alternate DUAL mode with signals of sufficient height ateach input. To avoid trigger problems due to different DCvoltage components, AC input coupling for both channels isrecommended.

The peak (value) detection which is normally present inautomatic triggering mode (AT), is automatically switched off;the LEVEL control becomes inoperative and the triggerthreshold is set to 0 Volt.

The internal trigger source is switched in the same way as thechannel switching after each time base sweep.

Phase difference measurement is not possible in this triggermode.

External triggering

The internal triggering is disconnected by depressing the TRIG.EXT. button. The time base can be triggered externally via theTRIG. EXT. socket using a 0.3Vpp to 3Vpp voltage, which is insynchronism with the test signal. This trigger voltage may havecompletely different form from the test signal voltage. Triggeringis even possible in certain limits with whole number multiplesor fractions of the test frequency, but only with synchronoussignals.

The input impedance of the TRIG. EXT. socket is approx.100kΩ II 10pF. The maximum input voltage of the input circuitis 100V (DC+peak AC).

It must be noted that a different phase angle between themeasuring and the triggering signal may cause a display notcoinciding with the SLOPE pushbutton setting. The triggercoupling selection can also be used in external triggering mode.Unlike internal triggering, the lowest frequency for externaltriggering is 20Hz in all trigger coupling conditions.

Trigger indicator

An LED on condition (above the SLOPE switch) indicates thatthe trigger signal has a sufficient amplitude and the LEVELcontrol setting is correct. This is valid with automatic and withnormal triggering. The indication of trigger action facilitates asensitive LEVEL adjustment, particularly at very low signalfrequencies. The indication pulses are of only 100ms duration.Thus for fast signals the TR-LED appears to glow continuously,for low repetition rate signals, the LED flashes at the repetitionrate or at a display of several signal periods not only at the startof the sweep at the left screen edge, but also at each signalperiod.

In automatic triggering mode the sweep generator startsrepeatedly without test signal or external trigger voltage. If thetrigger signal frequency is <20Hz the sweep generator startswithout awaiting the trigger pulse. This causes an untriggereddisplay and a flashing trigger LED (TR).

Holdoff-time adjustment

If it is found that a trigger point cannot be located on extremelycomplex signals even after repeated and careful adjustment ofthe LEVEL control, a stable display may be obtained using theHOLDOFF control. This facility varies the hold-off time betweentwo sweep periods approx. up to the ratio 10:1. Pulses or othersignal waveforms appearing during this off period cannottrigger the time base. Particularly with burst signals or aperiodicpulse trains of the same amplitude, the start of the sweep canbe delayed until the optimum or required moment.

A very noisy signal or a signal with a higher interfering frequencyis at times displayed double. It is possible that LEVEL adjustmentonly controls the mutual phase shift, but not the double display.The stable single display of the signal, required for evaluation,is easily obtainable by expanding the holdoff time. To this endthe HOLD OFF knob is slowly turned to the right, until onesignal is displayed. A double display is possible with certainpulse signals, where the pulses alternately show a smalldifference of the peak amplitudes. Only a very exact LEVELadjustment makes a single display possible. The use of theHOLD OFF knob simplifies the right adjustment.

After specific use the HOLD OFF control should be reset intoits calibration detent (fully ccw), otherwise the brightness ofthe display is reduced drastically. The function is shown in thefollowing figures.



Fig. 1 shows a case where the HOLD OFF knob is in the minimumposition and various different waveforms are overlapped on thescreen, making the signal observation unsuccessful.

Fig. 2 shows a case where only the desired parts of the signal arestably displayed.

Component Tester

General

The HM303-6 has a built-in electronic Component Tester(COMP. TESTER), which is used for instant display of a testpattern to indicate whether or not components are faulty. TheCOMP. TESTER can be used for quick checks of se-miconductors (e.g. diodes and transistors), resistors,capacitors, and inductors. Certain tests can also be made tointegrated circuits. All these components can be tested in andout of circuit.

The test principle is fascinatingly simple. A built-in generatordelivers a sine voltage, which is applied across the componentunder test and a built-in fixed resistor. The sine voltage across thetest object is used for the horizontal deflection, and the voltagedrop across the resistor (i.e. current through test object) is usedfor vertical deflection of the oscilloscope. The test pattern showsa current-voltage characteristic of the test object.

Since this circuit operates with a frequency of 50Hz (±10%)and a voltage of approx. 7Vrms (open circuit), the indicatingrange of the component tester is limited. The impedance ofthe component under test is limited to a range from 20Ω to4.7kΩ. Below and above these values, the test pattern showsonly short-circuit or open-circuit. For the interpretation of thedisplayed test pattern, these limits should always be borne inmind. However, most electronic components can normally betested without any restriction.

Using the Component Tester

The component tester is switched on by depressing theCOMP. TESTER pushbutton (on) beneath the screen. Thismakes the vertical preamplifier and the time base generatorinoperative. A shortened horizontal trace will be observed. Itis not necessary to disconnect scope input cables unless in-circuit measurements are to be carried out. In the COMP.TESTER mode, the only controls which can be operated areINTENS, FOCUS, X-POS. and X-MAG. X10 pushbutton(must be released). All other controls and settings have noinfluence on the test operation.

For the component connection, two simple test leads with4mm Ø banana plugs, and with test prod, alligator clip orsprung hook, are required. The test leads are connected to theinsulated socket and the adjacent ground socket beneath thescreen. The component can be connected to the test leadseither way round.

After use, to return the oscilloscope to normal operation,release the COMP. TESTER pushbutton (off).

Test Procedure

Caution!Do not test any component in live circuitry - remove allgrounds, power and signals connected to the componentunder test. Set up Component Tester as stated above.Connect test leads across component to be tested.Observe oscilloscope display.

Only discharged capacitors should be tested!

Test Pattern Displays

• Open circuit is indicated by a straight horizontal line.• Short circuit is shown by a straight vertical line.

Testing Resistors

If the test object has a linear ohmic resistance, both deflectingvoltages are in the same phase. The test pattern expected froma resistor is therefore a sloping straight line. The angle of slopeis determined by the resistance of the resistor under test. Withhigh values of resistance, the slope will tend towards thehorizontal axis, and with low values, the slope will movetowards the vertical axis.

Values of resistance from 20ΩΩΩΩΩ to 4.7kΩΩΩΩΩ can be approximatelyevaluated. The determination of actual values will come withexperience, or by direct comparison with a component of aknown value.

Testing Capacitors and Inductors

Capacitors and inductors cause a phase difference betweencurrent and voltage, and therefore between the X and Ydeflection, giving an ellipse-shaped display. The position andopening width of the ellipse will vary according to the impedancevalue (at 50Hz) of the component under test.

A horizontal ellipse indicates a high impedance or a relativelysmall capacitance or a relatively high inductance.

A vertical ellipse indicates a small impedance or a relativelylarge capacitance or a relatively small inductance.

A sloping ellipse means that the component has aconsiderable ohmic resistance in addition to its reac-tance.

The values of capacitance of normal or electrolytic capacitorsfrom 0.1µF to 1000µF can be displayed and approximate valuesobtained. More precise measurement can be obtained in asmaller range by comparing the capacitor under test with acapacitor of known value. Inductive components (coils,transformers) can also be tested. The determination of thevalue of inductance needs some experience, because inductorshave usually a higher ohmic series resistance. However, theimpedance value (at 50Hz) of an inductor in the range from 20Ωto 4.7kΩ can easily be obtained or compared.

Component Tester


Testing Semiconductors

Most semiconductor devices, such as diodes, Z-diodes,transistors, FETs can be tested. The test pattern displays varyaccording to the component type as shown in the figuresbelow.

The main characteristic displayed during semiconductor testingis the voltage dependent knee caused by the junction changingfrom the conducting state to the non conducting state. Itshould be noted that both the forward and the reversecharacteristic are displayed simultaneously. This is a two-terminal test, therefore testing of transistor amplification isnot possible, but testing of a single junction is easily andquickly possible. Since the test voltage applied is only verylow, all sections of most semiconductors can be testedwithout damage. However, checking the breakdown or reversevoltage of high voltage semiconductors is not possible. Moreimportant is testing components for open or short-circuit,which from experience is most frequently needed.

Testing Diodes

Diodes normally show at least their knee in the forwardcharacteristic. This is not valid for some high voltage diodetypes, because they contain a series connection of severaldiodes. Possibly only a small portion of the knee is visible. Z-diodes always show their forward knee and, up to approx. 9V,their Z-breakdown, forms a second knee in the oppositedirection. A Z-breakdown voltage of more than approx. 9V cannot be displayed.

The polarity of an unknown diode can be identified bycomparison with a known diode.

Testing Transistors

Three different tests can be made to transistors: base-emitter,base-collector and emitter-collector. The resulting test patternsare shown below.

The basic equivalent circuit of a transistor is a Z-diode betweenbase and emitter and a normal diode with reverse polaritybetween base and collector in series connection. There arethree different test patterns:

For a transistor the figures b-e and b-c are important. Thefigure e-c can vary; but a vertical line only shows short circuitcondition.

These transistor test patterns are valid in most cases, butthere are exceptions (e.g. Darlington, FETs). With the COMP.TESTER, the distinction between a P-N-P and an N-P-Ntransistor is discernible. In case of doubt, comparison with aknown type is helpful. It should be noted that the same socketconnection (COMP. TESTER or ground) for the same terminalis then absolutely necessary. A connection inversion effectsa rotation of the test pattern by 180 degrees round about thecenter point of the scope graticule.

Pay attention to the usual caution with single MOS-components relating to static discharge or frictionalelectricity!

In-Circuit Tests

The test patterns show some typical displays for in-circuittests.

Caution!During in-circuit tests make sure the circuit is dead. Nopower from mains/line or battery and no signal inputsare permitted. Remove all ground connections includingSafety Earth (pull out power plug from outlet). Removeall measuring cables including probes betweenoscilloscope and circuit under test. Otherwise bothCOMP. TESTER leads are not isolated against the circuitunder test.

Component Tester


In-circuit tests are possible in many cases. However, they arenot well defined. This is caused by a shunt connection of realor complex impedances - especially if they are of relativelylow impedance at 50Hz - to the component under test, oftenresults differ greatly when compared with single components.In case of doubt, one component terminal may be unsoldered.This terminal should then be connected to the insulatedCOMP. TESTER socket avoiding hum distortion of the testpattern.

Another way is a test pattern comparison to an identical circuitwhich is known to be operational (likewise without power andany external connections). Using the test prods, identical testpoints in each circuit can be checked, and a defect can bedetermined quickly and easily. Possibly the device itself undertest contains a reference circuit (e.g. a second stereo channel,push-pull amplifier, symmetrical bridge circuit), which is notdefective.

Component Tester


Element Function

POWER Turns scope on and off.(pushbutton + LED) LED indicates operating

condition.

INTENS Intensity control(knob) for trace brightness

TRACE ROTATION To align trace with horizontal(potentiometer; graticule line. Compensatesadjustment with influence of earth’s magneticscrewdriver) field.

FOCUS Focus control for(knob) trace sharpness.

Y-POS. I Controls vertical position(knob) of channel I display.

Inoperative in X-Y mode.

Y MAG. x5 When depressed, increasing of(pushbutton switch) Y-sensitivity CH I 5 fold (max.

1mV/div.)

Y MAG. x5 When depressed, increasing of(pushbutton switch) Y-sensitivity CH II 5 fold (max.

1mV/div.)

Y-POS. II Controls vertical position(knob) of channel II display.

SLOPE Selects the slope of the triggersignal.

Element Function

SLOPE / = rising edge;(pushbutton switch) \ = falling edge.

TR LED lights, if sweep is triggered.(LED)

LEVEL Adjustment of trigger level.(knob)

X-POS. Controls horizontal(knob) position of trace.

X-MAG. x10 10:1 expansion in the X direction.(pushbutton switch) Max. resolution 10ns/div.

(inoperative in XY-mode).

VOLTS/DIV. Channel I input attenuator.(12 position Selects Y input sensitivityrotary switch) in mV/div. or V/div.

in 1-2-5 sequence.

VAR. GAIN Fine adjustment of Y amplitude(knob) CH I. Increases attenuation factor

min. by 2.5 (left hand stop).For amplitude measurementmust be in CAL. position(right hand stop).

CH I/II-TRIG. I/II No button depressed: CH I only(pushbutton switch) and triggering from channel I.

When depressed, channel II onlyand triggering from channel II.(Trigger selection in DUAL

mode).

Front Panel Elements HM 303-6 (Brief Description - Front View)


Element Function

DUAL Button released:one channel only.

(pushbutton Button depressed: channel Iswitch) and channel II in alternating

mode.

CHOP. DUAL and ADD buttons depressed:CH I and CH II in chopped mode.

ADD ADD depressed only:(pushbutton switch) algebr. addition.

In combination with INV.:difference.

VOLTS/DIV. Channel II input attenuator.(12 position Selects Y input sensitivityrotary switch) in mV/div. or V/div.

in 1-2-5 sequence.

VAR. GAIN Fine adjustment of Y amplitude(knob) CH II. Increases attenuation

factor min. by 2.5 (left hand stop).For amplitude measurementmust be in CAL. position (righthand stop).

TRIG. MODE Trigger selector:(switch) AC: 10Hz-100MHz.AC-DC-LF-TV DC: DC-100MHz.

LF: DC-1.5kHz.TV: Triggering for frame and line.

AT/NM Button released = autom. trig.(pushbutton trace visible without input signal. switch) Button depressed = normal trig.

with LEVEL adjustment.

~ AT/NM and ALT pushbuttonsdepressed:Internal line triggering in combi-nation with normal triggering.

ALT Triggering alternates between(pushbutton switch) CH I and CH II in alternating

DUAL Channel mode only.

HOLD OFF Controls holdoff-time(knob) between sweeps.

Normal position = full ccw.

TIME/DIV. Selects time coefficients(rotary switch) (speeds) of time base,

from 0.2s/div. to 0.1µs/div.

Variable Variable adjustment of time base.time base control Decreases time deflection speed(center knob) at least 2.5 fold.

For time measurementsturn to right hand stop.

Element Function

XY Selects X-Y operation,(pushbutton switch) stops sweep.

X signal via CH I.Attention!Phosphor burn-in without signal.

TRIG. EXT. Button released = internal trig.(pushbutton switch) Button depressed = external

triggering, trigger signal via TRIG.EXT. BNC socket.

INPUT CH I Channel I signal input and input(BNC socket) for horizontal deflection in X-Y

mode.Input impedance 1MΩ II 20pF.

AC-DC Selects input coupling of CH I(pushbutton switch) vertical amplifier.

DC = direct couplingAC = coupling via capacitor.

GD GD = signal disconnected(pushbutton switch) from input, Y amplifier grounded.

Connector for reference potential(4mm socket) (galvanically connected to earth).

INPUT CH II CH II signal input.(BNC socket) Input impedance 1MΩ II 20pF.

AC-DC Selects input coupling of the CH II(pushbutton switch) vertical amplifier. Specs see (29).

GD GD = signal disconnected(pushbutton switch) from input, Y amplifier grounded.

INV. Inversion of CH II display.(pushbutton switch) In combination with ADD button

= difference CH I, CH II.

TRIG. EXT. Input for external trigger signal.(BNC socket) (Pushbutton TRIG. EXT. depressed.)

COMP. TESTER Switch to convert oscilloscope(pushbutton switch) to component tester mode.

Release X-MAG. X10 pushbutton.

COMP. TESTER Connectors for test leads(4mm sockets) of the Component tester.

0.2Vpp Calibrator square wave output(test socket) 0,2Vpp.

CALIBRATOR1kHz/1MHz Selects calibrator frequency.(pushbutton switch) Button released: approx. 1kHz,

Button depressed: approx. 1MHz.

Front Panel Elements HM 303-6 (Brief Description - Front View)


Short Instruction for HM303-6

Switching on and initial setting

Connect instrument to power outlet, depress red POWER button. LED indicates operating condition.Case, chassis and all measuring terminals are connected to the safety earth conductor (Safety Class I).

Do not depress any further button. TRIG. MODE selector switch to AC.AT/NM button released, CH I input coupling switch to GD, set TIME/DIV. switch to 50µs/div.Adjust INTENS control for average brightness.Center trace on screen using X-POS. and Y-POS.I controls. Then focus trace using FOCUS control.

Vertical amplifier mode

Channel I: CH I/II, DUAL and ADD pushbuttons in out position.Channel II: CH I/II pushbutton depressed.Channel I and II: DUAL pushbutton depressed. Alternate channel switching: ADD (CHOP.) pushbutton in out position. Signals <1kHz or time coefficient ³1ms/div: DUAL and ADD (CHOP.) buttons depressed.Channel I+II (sum): depress only ADD button.Channel I-II (difference): depress ADD and INV. pushbuttons.

Triggering mode

Select trigger mode with AT/NM pushbutton:AT = Automatic Peak (value) Triggering <20Hz to 60MHz (out position). NM = Normal Triggering (depressed).Trigger edge direction: select slope with SLOPE ( ) pushbutton.Internal triggering: select channel with TRIG. I/II (CH I/II) pushbutton.Alternating triggering (internal): DUAL and ALT. pushbuttons depressed, ADD (CHOP.) pushbutton in the out position.External triggering: TRIG. EXT. pushbutton depressed; sync signal (0.3Vpp to 3Vpp) to TRIG. EXT. socket.Line triggering (normal triggering): AT/NM and ALT pushbuttons depressed (~).Select trigger coupling with TRIG. MODE selector switch. Trigger frequency ranges:AC: >20Hz to 100MHz; DC: DC to 100MHz; LF: DC to 1.5kHz.TV: Composite video signal with line or horizontal frequency.

TIME/DIV. 0.2s/div. - 1ms/div. = field frequencyTIME/DIV. 0.5ms/div. - 0.1µs/div. = line frequency

Select edge direction with SLOPE ( ) pushbutton (sync. pulse above /, below \).Pay attention to trigger indicator: TR LED above the SLOPE pushbutton.

Measurements

Apply test signal to the vertical input connectors of CH I and/or CH II.Before use, calibrate attenuator probe with square wave CALIBRATOR-signal.Switch input coupling to AC or DC.Adjust signal to desired display height with attenuator switch (VOLTS/DIV.).Select time coefficient on the TIME/DIV. switch.Set trigger point with LEVEL knob for normal triggering.Trigger complex or aperiodic signals with longer HOLD OFF-time.Amplitude measurement with Y fine control at right stop (CAL.).Time measurement with time fine control at right stop (CAL.).Horizontal expansion 10 fold with X-MAG. x10 button depressed.External horizontal deflection (X-Y mode) with XY pushbutton depressed (X input: CH I).

Component Tester

Press COMP. TESTER pushbutton (on). Connect both component terminals to COMP. TESTER jacks.In-circuit test: Circuit under test must be disconnected from battery or power (pull out power plug), signals and ground (earth).Remove all signal connections to HM303-6 (cable, probe), release X-MAG. X10 pushbutton, then start testing.

M A N U A L • H A N D B U C H • M A N U E L

authorized dealer

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Oscilloscope HM303-6 - Rohde & Schwarz · Oscilloscope HM 303-6 3. ... HAMEG instruments fulﬁ ll the regulations of the EMC directive. The conformity test made by HAMEG is based