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Table of contents
Technical Data ....................P 1 Accessories ..................... Z 1
Operating Instructions General Information ............... M 1 Use of tilt handle ................. M 1 Safety. ...................... M 1 Operating conditions ................ M 2 Warranty ..................... M 2 Maintenance ................... M 2 Mains/Line voltage change ............ M 2 Type of Signal ................... M 3 Amplitude Measurements ............ M 3 Time Measurements ............... M 4 Connection of Test Signal ............ M 5 Operating ..................... M 6 First Time Operation ............... M 7 Trace Rotation TR ................. M 7 DC Balance Adjustment ............. M 7 Use and Compensation of Probes ........ M 8 Operating Modes of the Y Amplifier ....... M 9 X-Y Operation ................... Ml 0 X-Y Phase Measurements ............ Ml 0 Dual Trace Phase Difference Measurements . . M 10 Measurement of an amplitude modulation .... Ml 1 Triggering and Timebase ............. Ml 1 Triggering of video signals ............ Ml 2 Function of variable HOLD OFF control ...... M l 3 Sweep Delay /After Delay Triggeringe ...... Ml 3 Delay Mode Indication .............. Ml 5 Component Tester ................ Ml 5 Miscellaneous .................. Ml 7 Test Patterns ................... Ml 8 Short Instruction K 1. Front Panel Elements Folder with Front View .............. K 2 Test Instructions General .......................T 1 Cathode-Ray Tube: Brightness, Focus, Linearity, Raster Distortions . T 1 Astigmatismus Check ............... T 1 Symmetry and Drift of thevertical Amplifier .... T 1 Calibration of the Vertical Amplifier ......... T 1 Transmission Performance of the Vertical Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . T 2 Operating Modes: CH I/II-TRIG. l/II, DUAL, ADD, CHOP., INV. l/II and XY-Betrieb . T 2 Triggering Checks ................. T 3 Timebase ...................... T 3 SweepDelay ....................T 4 Component Tester ................. T 4 Trace Alignment .................. T 4 Miscellaneous ...................T 4
Subject to change without notice
Oscilloscope HM 604
Service Instructions General . . . . . . . . . . . . . . . . . Instrument Case Removal . . . . . . . Operating Voltages . . . . . . . . . . . Minimum Brightness . . . . . . . . . . Astigmatismus control . . . . . . . . . Trouble Shooting the Instrument . . . . Replacement of Components and Parts Replacement of the Power Transformer Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S S S S S S S S S 1 1 1 1 1 2 2 2 3
Circuit Diagrams Block Diagram ...................D 1 Wiring Diagram ...................D 2 Identification of Components ............ D 3 Y Input, Attenuator, Preamplifier CH. l/II ...... D 4 Y intermediate Amplifiers, Trigger Pre-Amplifiers, Component Tester ................ D 5 Y Final Amplifier .................. D 6 Post Trigger, Field Selector ............. D 7 Timebase (analog) ................. D 8 Timebase (digital) .................. D 9 Tim,ebase Generator ................ DlO X Final Amplifier, Calibrator ............. Dl 1 CRT and HV circuit ................. D12 Power Supply ....................D13 Component Locations XY Board ......................D14 TB Board ......................D15 PTFS Board .....................D16 TBG, CAL, YF Boards ................ D17 CO, EY, Z Boards .................. D18 9.88. 604
Specification
Vertical Mhtion
Operating modes: Channel I or Ch. II separate, Channel I and II: alternate or chopped. (Chopper frequency approx. 0.5MHz). Sum or difference of Ch. I and Ch. II, (with invert buttons for both Channels). XY-Mode: via Channel I and Channel II. Frequency range: 2x DC to 6OMHz (- 3dB). Risetime: approx. 5.8ns. Overshoot: II %. Deflection coefficients: 12 calibrated steps from 5 mV/div. to ZOV/div in l-Z-5 sequence, variable 2.5: 1 to min. 50V/cm. Accuracy in calibrated position: +3%. Y-Magnification x5 (calibrated) to 1 mV/div. (Frequency range DC to 20MHz. - 3dB. input impedance: 1 MQ II 3OpF. Input coupling: DC-AC-GD (Ground) Input voltage: max. 400V (DC + peak AC). Y-output from CH I or CH II, = 50 mV,Jdiv. (50 52) Delay Line: approx. 90ns.
Trigger System
With automatic lOHz-IOOMHz (P5mm height) normal with level control from DC- 100 MHz. LED indication for trigger action. Slope: positive or negative. Sources: Ch. I, Ch. II, line, external. Coupling: AC (21 OHz to approx. 20 MHz), DC LF (DC - 550 kHz), HF(?50kHzmlOOMHz). Threshold: external r50mV. Active TV-Sync-Separator for line and frame. Slope positive or negative. 2nd. Triggering (Del. Trig.): autom. or slope controlled (independent from slope direction). + selection for TV mode. Threshold: 1 div; typlcal 0.5div. Trigger bandwidth: 225 Hz to 60 MHz.
60 MHz Universal Oscilloscope
2 Channels, 1 mV/div. Sensitivity, Delay Line, Component Tester Timebase: 2.5s/div. to 5ns/div. including x10 Magnifier&Sweep Delay Triggering: DC-lOOMHz, TV Sync Separator, After-Delay Trigger
Time coefficients: 23 calibrated steps from 50ns/div. to 1 s/div in l-2-5 sequence, variable 2.5: 1 to min. 2.5s/div, accuracy in calibrated position: +3%. with X-Magnifier x10 (k 5%) to = 5nsIdiv.. Hold-Off time: variable (2 5 : 1). Delay: 7 decade steps from 1 OOns to 0.1 s, variable approx 10 : 1 to 1 s. Bandwidth X-Amplifier: DC-5MHz (-3dB). Input X-Amplifier via Channel II, sensitivity see Ch. II specification. X-Y phase shift: <3" below 120 kHz. Ramp output: approx 5V. positive going
Test voltage: max. 8.5V,,, (open circuit). Test current: max. 8mA,,, (shorted). Test frequency: 50 - 60 Hz (line frequency).
Cathode-ray tube: 150CTB31 P43l123, rectangular screen, internal graticule 8x10 cm. Total acceleration voltage: 12 kV. Trace rotation: adjustable on front panel. Calibrator: square-wave generator switchable from = 1 kHz to 1 MHz (t, approx. 3ns). Output voltage: 0.2V and 2V fl %. Protective system Safety Class I (IEC 348). Linevoltage: 110. 125, 220, 24OV- *IO%. Line frequency: 50 to 60Hz. Power consumption: = 40 Watt. Weight: approx. 8kg. Colour: techno-brown. Cabinet: W 285, H 145, D 380mm. Lockable tilt handle.
With its variety of operating and trigger modes, the HM604 is a new innovative general purpose oscilloscope satisfying a wide range of exacting requirements in laboratory, production, and service. The dual-channel measurement amplifier ensures highly faithful waveform transfer characteristics, which can be readily checked on the built-in fast-risetime 1 MHz Calibrator from probe tip to CRT screen! Using Y-axis magnification, the instrument's high sensitivity enables stable displays of very small signals as low as 0.5 mV. An analog output is provided for connecting multimeters or counters. Another important feature is the internal delay line for observations of the leading edge of a signal. As in dual-time base oscilloscopes, the HM604 features a calibrated sweep delay mode, allowing smallest waveform sections to be expanded up to 1000 times. The HM604's most outstanding feature, however, is the unique, newly developed automatic After-Delay Trigger mode to ensure extremely stable displays and jitter-free measurements of asynchronous signal sections and bursts or pulse trains, independent of amplitude fluctuations. An active TVSync-Separator further enhances trigger quality of video frame and line signals. In the alternate trigger mode, two signals of different frequencies can be compared. With this state-of-the-art oscilloscope, HAMEG again sets a new price/ performance standard which is not likely to be met by others in this category. Users will be particularly impressed by the instrument's outstanding versatility and ease of operation. These features are possible in the HM604 due to HAMEG's meticulous attention to detail and many decades of successful design experience.
Subject to change without notice
Test Cable Banana - BNC
HZ32
Coaxial test cable; length 1.15 m, characteristic impedance 5Ofi. Cable capacitance 12OpF. Input voltage max. 5OOV,.
Test Cable BNC-BNC
HZ34
Coaxial test cable; length 1 m, characteristic impedance 500. Cable capacitance 126pF. Input voltage max. 5OOV,.
Adapter Banana - BNC
HZ20
Two 4mm binding posts (19mm between centers) to standard BNC male plug. input voltage max. 5OOV,.
5Ofz Through-Termination Modular Probes
The clear advantage over ordinary probes are field replaceable parts and the HF-compensation feature on the 10: 1 attenuator probes For the first time, probes in this price range allow adjustments of their HF-characteristics to match individually the input impedance of each scope. This is particularly important for scopes with higher bandwidths (>SOMHz), as otherwise strong overshoot or rounding may occur, when measuring fast-rising square waves. An exact HF-compensation, however, is only possible with squarewave generators having a risetime <5ns. Most HAMEG scopes already feature such a calibration generator. For other oscilloscopes, it is available as accessory item HZ60-2. At present the following Modular Probes are available (HZ36 without HF-compensation):
HZ22
For terminating systems with 5OS2 characteristic impedance. Maximum load 2 W. Max. voltage 1 OV,,,.
Carrying Cases
For HM 103 For HM203, HM204. HM205, HM208, HM408. HM604, HM605 and HM 1005
HZ95 HZ96
Viewing Hood
For HM203, HM204, HM205, HM208, HM408,
HZ47
HM604, HM605
and HM 1005
Scope-T-tar
Type
Attenuation Ratio
Bandwidth min. (MHz) HZ36 HZ51 1O:l 150 HZ52 IO:1 HZ53
HZtiOa
selectable
l:l/lO:l IO/ 100
HZ54 selectable 1:1/10:1 IO/ 150 35/<2 40/I 8 l/10 600 1.2 HZ39 HZ57 HZ46
(HF)
250
1OO:l
150 <2 65 100 1200 1.5
Risetime (ns)
Inp. Capacitance (pF) Inp. Resistance (MR) Inp. Voltage max. (V,) Cable Length (m) Spare Cable for HZ36
3513.5
47/18 l/10 600 1.5
<2
16 10 600 1.2
tl.4
16 10 600 1.5
For Checking the Y amplifier, timebase, and compensation of all probes, the HZ6O-2 is a crystal-controlled, fast rising (typ. 3ns) square-wave generator with switchable frequencies of DC, 1 -lOIOOHz, I-IO-I OOkHz, and 1 MHz. Three BNC outputs provide signals of 25 mV,, into 50 M, 0.25V,, and 2.5V,, (open circuit for 1 Ox and 100x probes); accuracy +q %. Battery-powered.
Component-Tester
HZ65
Spare Cable for HZ51, HZ54 Sparepart Kit (2 sprung hooks, 2 screw tips, 1 ground cable)
Special probe for AM-demodulation and wobbulator measurements. HF-Bandwidth IOOkHz -5OOMHz (+ldB). AC InputVoltage 250mV - 5OV,,,. DC isolation Voltage 200V DC including peak AC. Cable length 1.2m.
Indispensable for trouble-shooting in electronic circuits. Single component and in-circuit tests are both possible. The HZ65 operates with all scopes, which can be switched to X-Y operation (ext. horizontal deflection). Non-destructive tests can be carried out on almost all semiconductors, resistors, capacitors, and coils. Two sockets provide for quick testing of the 3 junction areas in any small power transistor. Other components are connected by using 2 banana jacks. Test leads supplied.
Examples of Test Displays:
ShortcircuIt Capacitor 33~F Junction E-C Z-Diode t8V
High Vdtaget I'mbe
Hz58
For measurement of voltages up to 15kV,,. Input resistance approx. 500 mQ. Recommended load resistance1 Ma/l 0 MQ (switchable). Attenuation ratio 1000 : 1. Bandwidth 1 MHz. Cable length 1.5 m. BNC connector.
Printed in West Germany 5/90
Zl
Operating Instructions
General Information
This oscilloscope is easy to operate. The logical arrangement of the controls allows anyone to become familiar with the operation of the instrument after a short time, however, experienced users are also advised to read through these instructions so that all functions are understood. Immediately after unpacking, the instrument should be checked for mechanical damage and loose parts in the interior. If there is transport damage, the supplier must be informed immediately. The instrument must then not be put into operation. Check that the instrument is set to the correct mains/line voltage. If not, refer to instructions on page M2.
Safety
This instrument has been designed and tested in accordance with IECPublication346,SafetyRequirementsfor Electronic Measuring Apparatus, and has left the factory in a safe condition. The present instruction manual contains important information and warnings which have to be followed by the user to ensure safe operation and to retain the oscilloscope in safe condition. The case, chassis and all measuring terminals are connected to the protective earth contact of the appliance inlet. The instrument operates according to Safety C/ass I (three-conductor power cord with protective earthing conductor and a plug with earthing contact). The mains/line plug shall only be inserted in a socket outlet provided with a protective earth contact. The protective action must not be negated by the use of an extension cord without a protective conductor. Warning! Any interruption of the protective conductor inside or outside the instrument or disconnection of the protective earth terminal is likely to make the instrument dangerous. Intentional interruption of the protective earth connection is prohibited. The mains/line plug should be inserted before connections are made to measuring circuits. The grounded accessible metal parts (case, sockets, jacks) and the mains/line supply contacts (line, neutral) of the instrument have been tested against insulation breakdown with 2000 Vr.m.s. (5OHz). Under certain conditions, 50 Hz or 60Hz hum voltages can occur in the measuring circuit due to the interconnection with other mains/line powered equipment or instruments. This can be avoided by using an isolation transformer (Safety Class II) between the mains/line outlet and the power plug of the instrument. When displaying waveforms where the "low-level" side of the signal is at a high potential, even with the use of a protective isolation transformer, it should be noted that this potential is connected to the oscilloscope's case and other accessible metal parts. High voltages are dangerous. In this case, special safety precautions are to be taken, which must be supervised by qualified personnel if the voltage is higher than 42V. Most cathode-ray tubes develop X-rays. However, t h e dose equivalent rate falls far below the maximum permissible value of 36pA/kg (0.5mRlh). Whenever it is likely that protection has been impaired, the instrument shall be made inoperative and be secured against any unintended operation. The protection is Ii kely to be impaired if, for example, the instrument - shows visible damage, - fails to perform the intended measurements, - has been subjected to prolonged storage under unfavourable conditions (e.g. in the open or in moist environments), - has been subject to severe transport stress (e.g. in poor packaging). Ml
Use of tilt handle
To view the screen from the best angle, there are three different positions (C, D, E) for setting up the instrument. If the instrument is set down on the floor after being carried, the handle remains automatically in the upright carrying position (A). In order to place the instrument onto a horizontal surface, the handle should be turned to the upper side of the oscilloscope (C). For the D position (IO' inclination), the handle should be turned in the opposite direction out of the carry ing position until it locks in place automatically underneath the instrument. For the E position (20" inclination), the handle should be pulled to release it from the D position and swing backwards until it locks once more. The handle may also be set to a position for horizontal carrying by turning it to the upper side to lock in the B position. At the same time, the instrument must be moved upwards, because otherwise the handle will jump back.
6
Subject to change without notice
B
E
cict
20"
Operating conditions
The instrument has been designed for indoor use. The permissible ambient temperature range during operation is + 15°C . . . +3O"C. It may occasionally be subjected to temperatures between + 10°C and - 10°C without degrading its safety. The permissible ambient temperature range for storage or transportation is -40°C . +70X. The maximum operating altitude is up to 2200m (nonoperating 15000m). The maximum relative humidity is up to 80%. If condensed water exists in the instrument it should be acclimatized before switching on. In some cases (e.g. extremely cold oscilloscope) two hours should be allowed before the instrument is put into operation. The instrument should be kept in a clean and dry room and must not be operated in explosive, corrosive, dusty, or moist environments The oscilloscope can be operated in any position, but the convection cooling must not be impaired. The wentilation holes may not be covered. For continuous operation the instrument should be used in the horizontal position, preferably tilted upwards, resting on the tilt handle. The specifications stating tolerances are only valid if the instrument has warmed up for 30 minutes at an ambient temperature between +15C" and +3OC9 Values not stating tolerances are typical for an average instrument.
Maintenance
Various important properties of the oscilloscope should be carefully checked at certain intervals. Only in this way is it largely certain that all signals are displayed with the accuracy on which the technical data are based. The test methods described in the test plan of this manual can be performed without great expenditure on measuring instruments. However, purchase of the new HAMEG scope tester HZ 60, which despite its low price is highly suitable for tasks of this type, is very much recommended. The exterior of the oscilloscope should be cleaned regularly with a dusting brush. Dirt which is difficult to remove on the casing and handle, the plastic and aluminium parts, can be removed with a moistened cloth (99% water +I % mild detergent). Spirit or washing benzine (petroleum ether) can be used to remove greasy dirt. The screen may be cleaned with water or washing benzine (but not with spirit (alcohol) or solvents), it must then be wiped with a dry clean lint-free cloth. Under no circumstances may the cleaning fluid get into the instrument. The use of other cleaning agents can attack the plastic and paint surfaces.
Switching over the mains/line voltage
The instrument is set for 220V (240V U.K.) line voltage on delivery. It can be switched over to other voltages at the fuse holder combined with the 3-pole appliance inlet at the rear of the instrument. Firstly the fuse holder printed with the voltage values is removed using a small screw driver and - if required - provided with another fuse. Refer to the table below for the prescribed value of the fuse. Then replace the fuse holder so that the impressed white triangle points to the desired voltage. Here pay attention that the cover plate is also correctly engaged. The use of repaired fuses or short circuiting the fuse holder is not allowed. Damage arising because of this is not covered by the guarantee.
Warranty
Each instrument runs through a quality test with 10 hour burn-in before leaving the production. Practically every early failure is detected in intermittent operation by this method. However, it is possible that a component fails only after a lengthy operating period. Therefore a functional guarantee of 2 years is given for all units. The condition for this is that no modifications have been made in the instrument. In the case of shipments by post, rail or carrier it is recommended that the original packing is carefully preserved. Transport damages and damage due to gross negligence are not covered by the guarantee. In the case of a complaint, a label should be attached to the housing of the instrument which describes briefly the faults observed. If at the same time the name and telephone number (dialing code and telephone or direct number or department designation) is stated for possible queries, this helps towards speeding up the processing of guarantee claims.
Fuse type: Size 5 x 20 mm; 250 V-, C; IEC 127, Sheet III; DIN 41 662 (possibly DIN .41 571 sheet 3). Cutoff: time lag (T). Fuse rating Line voltage TO.63 A llOV-flO% TO.63 A 125V- &IO% T0.315A 22ov- &IO% T0.315A 24OV- &IO%
M2
Subject to change wlthout notice
Type of Signal
All types of signals with a frequency spectrum below 60 MHz can be displayed on the HM 604. The display of simple electrical processes such as sinusoidal RF and AF signals or ripple poses no problems. However, when square or pulse-shaped signals are displayed it must be remembered that their harmonic content must also be transmitted. In this case, the bandwidth of the vertical amplifier must be considerably higher than the repetition frequency of the signal. In view of this, accurate evaluation of such signals with the HM 604 is only possible up to a maximum repetition rate of 6MHz. Operating problems can sometimes occur when composite signals are to be displayed, especially if they do not contain any suitable level components and repetition frequency which can be used for triggering. This occurs, for example, with burst signals. To obtain a stably triggered display in these cases, it may be necessary to use Normal Triggering, HOLD OFF time control, and/or TIME/DIV. variable control. Video signals are easily triggerable by the aid of the active TV sync separator (TV SEP. switch). For optional operation as a DC or AC voltage amplifier, each channel is provided with a DC-AC coupling switch. The DC position should only be used with an attenuator probe or at very low frequencies or if the determination of DC voltage content of the signal is absolutely necessary. However, when investigating very low-frequency pulses, misleading ramp-offs may occur with AC coupling. In this case, DC operation is to be preferred if the signal voltage is not superimposed on a too high DC voltage level. Otherwise, a capacitor of adequate capacitance must be connected before the input of the vertical amplifier (switched to DC coupling). It should be remembered that this capacitor must have a sufficiently high breakdown voltage. DC operation is also recommended for the display of logic and pulse signals, particularly if their pulse duty factor changes permanently during operation. Otherwise, the display will move up and down with any change. DC voltages can only be measured in the DC position.
If a sinusoidal waveform, displayed on the oscilloscope screen, is to be converted into an effective (rms) value, the resulting peak-to-peak value must be divided by 2x- = 2.83. Conversely, it should be observed that sinusoidal voltages indicated in V,,, (V,,,) have 2.83 times the potential difference in V,,. The relationship between the different voltage magnitudes can be seen from the following figure.
Voltage values of a sine curve v rms = effective value; V, = simple peak or crest value;
V,, = peak-to-peak value; V,,, = momentary value.
The minimum signal voltage required at the vertical amplifier input for a display of 1 cm is approximately 7mV,,. This is achieved with the attenuator control set at 5mV/cm, its variable control in the fully clockwise position and pulled out. However, smaller signals than this may also be displayed. The deflection coefficients on the input attenuators are indicated in mV/cm or V/cm (peak-to-peak value). The magnitude of the applied voltage is ascertained by multiplying the selected deflection coefficient by the vertical display height in cm. If an attenuator probe x 70 is used, a further multiplication by a factor of 70 is required to ascertain the correct voltage value. For exact amplitude measurements the variable control on the attenuator switch must be set to its calibrated detent CAL. When turning the variable control ccw the sensitivity will be decreased by a factor of 2.5. Therefore every intermediate value is possible within the 7-2-5 sequence. With direct connection to the vertical input, signals up to 4OOV,, may be displayed (attenuator set to ZOV/cm, variable control ccw). When pulling the variable control knob (MAG x5), the sensitivity is increased by a factor of 5. Hence follows a min. deflection coefficient of 1 mV/cm (reduced bandwidth). With the designations H = display height in cm, U = signal voltage in V,, at the vertical input, D = deflection coefficient in V/cm at attenuator switch, the required quantity can be calculated from the two given quantities: D+ H=; U = D-H
Amplitude Measurements
In general electrical engineering, alternating voltage data normally refers to effective values (rms = root-meansquare value). However, for signal magnitudes and voltage designations in oscilloscope measurements, the peak-topeakvoltage (V,,) value is applied. The latter corresponds to the real potential difference between the most positive and most negative points of a signal waveform.
Subject to change without notice
M3 604
However, these three values are not freely selectable. They have to be within the following limits (trigger threshold, accuracy of reading): H between 0.5 and 8cm, if possible 3.2 to 8cm, U between 1 mV,, and 16OV,,, D between 5mV/cm and 20V/cm in l-2-5 sequence. D between 1 mV/cm and 4V/cm in l-2-5 sequence (with pulled MAG x5 knob). Examples: Set deflection coefficient D = 50 mV/cm 2 0.05 V/cm, observed display height H = 4.6 cm, required voltage U = 0.05.4.6 = 0.23 V,,. Input voltage U = 5V,,, set deflection coefficient D = 1 V/cm, required display height H = 5: 1 = 5cm Signal voltage U = 22OV,,;2.fl= 622 V,, (voltage > 16OV,,, with probe X 10 : U = 62.2 V,,), desired display height H = min. 3.2cm, max. 8cm. max. deflection coefficient D = 62.2 : 3.2 = 19.4V/cm, min. deflection coefficient D = 62.2 : 8 = 7.8V/cm, adjusted deflection coefficient D = lOV/cm If the applied signal is superimposed on a DC (direct voltage) level the total value (DC + peak value of the alternating voltage) of the signal across the Y-input must not exceed *4OOV(see figure). This same limit applies to normal x 10 attenuator probes, the attenuation ratio of which allows signal voltages up to approximately 1 ,OOOV,, to be evaluated. Voltages of up to approximately 2,4OOV,, may be measured by using the HZ53 high voltage probe which has an attenuation ratio of 100: 1. It should be noted that its AC peakvalue is derated at higher frequencies. If a normal x 10 probe is used to measure high voltages there is the risk that the compensation trimmer bridging the attenuator series resistor will break down causing damage to the input of the oscilloscope. However, if for example only the residual ripple of a high voltage is to be displayed on the oscilloscope, a normal x 10 probe is sufficient. In this case, an appropriate high voltage capacitor (approx. 22-68nF) must be connected in series with the input tip of the probe.
Voltage ' DC + AC,,,k = 4OOV,,,.
It is very important that the oscilloscope input coupling is set to DC, if an attenuator probe is used for voltages higher than 400V (see page M6: Connection of Test Signal).
Time Measurements
As a rule, all signals to be displayed are periodically repeating processes and can also be designated as periods. The number of periods per second is the recurrence frequency or repetition rate. One or more signal periods or even part of a period may be shown as a function of the adjustment of the TIMEIDIV. switch. The time coefficients on the TIME/ DIV. switch are indicated in s/cm, ms/cm, and ps/cm. Accordingly, the dial is subdivided into three sectors. The duration of a signal period or a portion of the waveform is ascertained by multiplying the relevant time (horizontal distance in cm) by the time coefficient selected on the TIME/DIV. switch. The time variable control (small knob on the TIME/DIV. switch) must be in its calibrated detent CAL. for accurate measurement (arrow horizontal and pointing to the right). With the designations L = displayed wave length in cm of one period, T = time in seconds for one period, F = recurrence frequency in Hz of the signal, T, = time coefficient in s/cm on timebase switch and the relation F = l/T, the following equations can be stated : T = L.T, F 1 L.Tc 1 L = F.Tc T, = ; T, = & .
=
With X-MAG. xl0 button depressed the T, value must be divided by 10. However, these four values are not freely selectable. They have to be within the following'limits: L between 0.2 and 1 Ocm, if possible 4 to 1 Ocm, T between 5 ns and 1 O S, F between 0.1 Hz and 60 MHz, T, between 50ns/cm and 1 s/cm in l-2-5 sequence (with X MAG. x 10 in out position), and T, between 5 ns/cm and lOOms/cm in l-2-5 sequence (with pushed X MAG. x10 button). Examples: Displayed wavelength L = 7 cm, set time coefficient T, = 0.5 ps/cm, required period T = 7.0.5.1 O-" = 3.5~s required rec. freq. F = 1:(3.5.1 OP6) = 286 kHz. Signal period T = 0.5s, set time coefficient T, = 0.2 s/cm, required wavelength L = 0.5 : 0.2 = 2.5cm.
Subject to
I
peak AC DC .-
-.
F@u DC /\ / -1 \ / `\ AC \ / \ Time 1' \ \. c / \
\\ \, / Total value of input voltage ' - ' The dotted line shows a voltage alternating at zero volt level. When superimposed a DC level, the addition of the positive peak and the DC voltage results in the max. voltage (DC + AC,,,,).
M4 604
I
\1
/!
`\
/
change without notice
Displayed ripple wavelength L = 1 cm, set time coefficient T, = 10 ms/cm, required ripple freq. F = 1 : (1 .10.10-3) = 100Hz. TV-line frequency F = 15 625 Hz, set time coefficient T, = 10 @cm, required wavelength L = 1: (15 625.1 0p5) = 6.4cm. Sine wavelength L = min. 4cm, max. 1 Ocm, Frequency F = 1 kHz, max. time coefficient T, = 1 : (4.1 03) = 0.25ms/cm, min. time coefficient T, = 1 :(I O-1 03) = 0.1 m&m, set time coefficient T, = 0.2 ms/cm, required wavelength L = 1: (1 03- 0.2 - 1 0p3) = 5cm. Displayed wavelength L = 0.8cm, set time coefficient T, = 0.5 ys/cm, pressed MAG X 10 button: T, = 0.05 @cm, required rec. freq. F = 1: (0.8.0.05.1 Ov6) = 25 MHz, required period T = 1: (25.1 06) = 40 ns. If the time is relatively short as compared with the complete signal period, an expanded time scale should always be applied (X MAG x10 button pushed). In this case, the ascertained time values have to be divided by 70. Very small time intervals at optional points of the signal can be measured more exactly with the aid of the sweep delay. With it, the display and measurement of time intervals, which are smaller than 1 % of the full signal period, are possible. The smallest measurable time interval is, on the whole, dependent on the obtainable brightness of the CRT. The limit is an expansion of approximately 1000 times. Using a Viewing Hood HZ47, more expansion is possible, provided that the time coefficient set on the TIME/DIV. switch is greater than S@cm (and using the X MAG x 10 facility) for the signal's basic period. Otherwise, the fastest sweep speed determines the greatest possible expansion. When investigating pulse or square waveforms, the critical feature is the risetime of the voltage step. To ensure that transients, ramp-offs, and bandwidth limits do not unduly influence the measuring accuracy, the risetime is generally measured between 10% and 90% of the vertical pulse height. For peak-to-peak signal amplitude of 6cm height, which are symmetrically adjusted to the horizontal center line, the internal graticule of the CRT has two horizontal dotted lines &2.4cm from the center line. Adjust the Y attenuator switch with its variable control together with the Y-POS. control so that the pulse height is precisely aligned with the 0 and 100 % lines. The 10 % and 90 % points of the signal will now coincide with the two lines, which have a distance of f2.4cm from the horizontal center line and an additional subdivision of 0.2cm. The risetime is given by the product of the horizontal distance in cm between these two coincidence points and the time coefficient setting.
Subject to change wlthout notlce
If magnification is used, this product must be divided by 10. The fall time of a pulse can also be measured by using this method. 100%
90%
-I qot tThe above figure shows correct positioning of the oscilloscope trace for accurate risetime measurement. With a time coefficient of O.O5ys/cm and pushed X MAG x10 button the example shown in the above figure results in a measured total risetime of ttor = 1.6cm.O.O5@cm: 10 = 8 n s When very fast risetimes are being measured, the risetimes of the oscilloscope amplifier and the attenuator probe have to be deducted from the measured time value. The risetime of the signal can be calculated using the following formula.
t, =
v ttot2 - t
osc
2 - tP2
In this ttot is the total measured risetime, to,, is the risetime of the oscilloscope amplifier (approx. 5.8ns), and t, the risetime of the probe (e.g. = 2 ns). If ttot is greater than 42 ns, then t,,, can be taken as the risetime of the pulse, and calculation is unnecessary. Calculation of the example in tie figure above results in a signal risetime t, = V 8* - 5.8* - 2* = 5.1 ns
Connection of Test Signal
Caution: When connecting unknown signals to the oscilloscope input, always use automatic triggering and set the DC-AC input coupling switch to AC. The attenuator switch should initially be set to POV/cm. Sometimes the trace will disappear after an input signal has been applied. The attenuator switch must then be turned back to the left, until thevertical signal height is only3-8cm. With a signa! amplitude greater than 16OV,,, an attenuator probe must be inserted before the oscilloscope's vertical input. If, after applying the signal, the trace is nearly blanked, the period of the signal is probably substantially
longer than the set value on the TIMEIDIV. switch. It should be turned to the left to an adequately greater time coefficient. The signal to be displayed should be fed to the vertical input of the oscilloscope by means of a shielded test cable, e.g. the HZ32 or HZ34, or by a x 10 or x 100 attenuator probe. The use of these shielded cables with high impedance circuits is only recommended for relatively low frequencies (up to approx. 50kHz). For higher frequencies, and when the signal source is of low impedance, a cable of matched characteristic impedance (usually 5OQ) is recommended. In addition, and especially when investigating square or pulse waveforms, a resistor equivalent to the characteristic impedance of the cable must also be connected to the cable directly at the input of the oscilloscope. When using a 509 cable, such as the HZ34, a 50R through-termination type HZ22 is available from HAMEG. When investigating square or pulse waveforms with fast risetimes, transient phenomena on both the edge and top of the signal may become visible if the correct termination is not used. It must be remembered that the 5OQ through-termination will only dissipate a maximum of 2 watts. This power consumption is reached with 1 OV,,, or with 28V,, sine signal. If a x 10 or x 100 attenuator probe is used, no termination is necessary. In this case, the connecting cable is matched directly to the high impedance input of the oscilloscope. When using attenuator probes even high internal impedance sources are only slightly loaded by approximately 10 MQ I I 16 pF or 100 MQ I I7 pF respectively. Therefore, when the voltage loss due to the attenuation of the probe can be compensated by a higher sensitivity setting on the HM 604, the probe should always be used. Also it should be remembered that the series impedance of the probe provides a certain amount of protection for the input of the oscilloscope amplifier. It should be noted that all attenuator probes must be compensated in conjunction with the oscilloscope (see: Probe Adjustment, page M8). If a x IO or x 100 attenuator probe is used at voltages higher than 400 V, the DC input coupling must always be set. With AC coupling, the attenuation is frequency-dependent, the pulses displayed can exhibit ramp-off, DC-voltage contents are suppressed - but loads the respective input coupling capacitor of the oscilloscope. The electric strength of which is maximum 400V (DC + peak AC). For the suppression of unwanted DC voltages, a capacitor of adequate capacitance and electric strength may be connected before the input tip of the probe (e.g. for ripple measurements). It is important to remember that when low voltage signals are being investigated the position of the ground point on the test circuit can be critical. This ground point should always be located as close as possible to the measuring point. If this is not done, serious signal deformation may M6 604
result from any spurious currents through the ground leads or test chassis parts. This comment also applies to the ground leads on attenuator probes which ideally should be as short and as thick as possible. For connection of a probe to a BNC socket, a BNC-adapter should be used. It forms often a part of the probe accessory. Grounding and matching problems are then eliminated. Hum or interference voltage appearing in the measuring circuit (especially with a small deflection coefficient) is possibly caused by multiple grounding, because equalizing currents can flow in the shielding of the measuring cables (voltage drop between non-fused earthed conductors of other line powered devices, which are connected to the oscilloscope or test object, e.g. signal generators with anti-interference capacitors).
Operating
For a better understanding of these Operating Instructions the front panel picture at the end of these instructions can be unfolded for reference alongside the text. The front panel is subdivided into three sections according to the various functions. The INTENS., FOCUS and TR (trace rotation) controls are arranged on the left directly below the screen of the cathode-ray tube (CRT). Continuing towards the right are the horizontal magnification button (X MAG. x10), the switch for calibrator frequency selection (1 kHz/l MHz) and calibrator output sockets 0.2V/2V (CAL.). The COMPONENT TESTER pushbutton and its measuring socket are located on the right side. The X-Section, located on the upper right, next to the screen, contains the red POWER pushbutton and indicating LED, all controls for timebase (TIME/DIV.), triggering (TRIG.), horizontal trace position (X-POS.), sweep delay (DELAY), TV separator (TV SEP.) together with the field select button (FIELD l/II), the XYmode button (XV), and the knob for holdoff adjustment (HOLD OFF). The lower Y-Section contains the controls for the vertical deflection system. On the right and left in this section are located: vertical input connector, DC-AC-GD input coupling slide switch, Y-POS. control, INVERT pushbutton, attenuator switch with variable control, and ground jack. All these controls and connectors exist in duplicate for each of the Channels I and II. Three pushbuttons for selecting the operating mode are arranged below the attenuator switches: CH l/II -TRIG l/II, DUAL and ADD. These are explained later. The instrument is so designed that even incorrect operation will not cause serious damage. The pushbuttons control only minor functions, and it is recommended that before commencement of operation all pushbuttons are in the "out" position. After this the pushbuttons can be operated depending upon the mode of operation required.
Subject to change without notice
The HM 604 accepts all signals from DC (direct voltage) up to a frequency of at least 60MHz (-3dB). For sinewave voltages the upper frequency limit will be 80MHz. However, in this higher frequency range the vertical display height on the screen is limited to approx. 6cm. The time resolution poses no problem. For example, with 100 MHz and the fastest adjustable sweep rate (5ns/cm), one cycle will be displayed every 2cm. The tolerance on indicated values amounts to f3% in both deflection directions. All values to be measured can therefore be determined relatively accurately. However, from approximately 25 MHz upwards the measuring error will increase as a result of loss of gain. At 40MHz this reduction is about 10%. Thus, approximately 11 % should be added to the measured voltage at this frequency. As the bandwidth of the amplifiers differ (normally between 65 and 70 MHz), the measured values in the upper limit range cannot be defined exactly. Additionally, as already mentioned, for frequencies above 60MHz the dynamic range of the display height steadily decreases. The vertical amplifier is designed so that the transmission performance is not affected by its own overshoot.
To obtain the maximum life from the cathode-ray tube, the minimum intensity setting necessary for the measurement in hand and the ambient light conditions should be used. Particular care is required when a single spot is displayed, as a very high intensity setting may cause damage to the fluorescent screen of the CRT. Switching the oscilloscope off and on at short intervals stresses the cathode of the CRT and should therefore be avoided.
Trace Rotation TR
In spite of Mumetal-shielding of the CRT, effects of the earth's magnetic field on the horizontal trace position cannot be completely avoided. This is dependent upon the orientation of the oscilloscope on the place of work. A centred trace may not align exactly with the horizontal center line of the graticule. A few degrees of misalignment can be corrected by a potentiometer acessible through an opening on the front panel marked TR.
DC Balance Adjustment First Time Operation
Check that the instrument is set to the correct mains/ line voltage. (Refer to page M2). Before applying power to the oscilloscope it is recommended that the following simple procedures are performed: - Check that all pushbuttons are in the out position, i.e. released. - Rotate the three variable controls with arrows to their calibrated detent. - Set the variable controls with marker lines to their midrange position (marker lines pointing vertically). - The LEVEL control knob should be on its left stop (AT). - The three lever switches in the X-Section should be set to their uppermost position. - Both input coupling slide switches for CH.1 and CH.11 in the Y-Section should be set to the GD position. Switch on the oscilloscope by depressing the red POWER pushbutton. An LED will illuminate to indicate working order. The trace, displaying one baseline, should be visible after a short warm-up period of 10 seconds. Adjust Y-P0S.I and X-POS. controls to center the baseline. Adjust INTENS. (intensity) and FOCUS controls for medium brightness and optimum sharpness of the trace. The oscilloscope is now ready for use. If only a spot appears (CAUTION! CRT phosphor can be damaged.), reduce the intensity immediately and check that the X-Y pushbutton is in the released (out) position. If the trace is not visible, check the correct positions of all knobs and switches (particularly LEVEL knob in AT position and DELAY MODE lever switch to OFF). The vertical preamplifiers for CH.1 and CH.11 contain matched dual FETs connected as input source followers. After long periods of use the FET characteristics may change which can alter the DC balance of the vertical amplifier. A quick check of DC Balance can be made on each channel by pulling the fine amplitude control MAG x5 and pushing it back. If the trace moves from the vertical position (up or down) more than 1 mm, the DC Balance will require readjustment. This check should be made after a 20-minute warm-up period.
Adjustment procedure
The following instructions should be performed to obtain the correct DC balance adjustment of both channels. - Remove all input cables and adjust oscilloscope controls to display the baseline. - Center the baseline using Y-POS. and X-POS. controls. - Set attenuator switches to 5mV/cm and input coupling switches to GD. - Release all pushbuttons in the Y-Section. - Place the oscilloscope so that it rests firmlyon its back (upright position) and locate DC balance adjustment potentiometer access holes - marked CH.1 DC-BALANCE CH.11 - which are found underneath the instrument. - Insert a screwdriver (blade approx. 3mm, length min. 20 mm) in CH.1 hole. A plastic guide with slotted bottom is located behind the hole. - Pull and push the CH.1 variable control MAG x5 and adjust balance pot so that the baseline no longer moves up or down. When the trace remains steady, correction of CH.1 is completed. - Depress CH I/II-TRIG. l/II button. Repeat adjustment procedure for CH.II. M7 604
Subject to change without notice
Use and Compensation of Probes
To display an undistorted waveform on an oscilloscope, the
probe must be matched to the individual input impedance of the vertical amplifier. The HM604's built-in calibration generator provides a squarewave signal with a very low risetime (<5ns), and switch-selectable frequencies of approx. 1 kHz and 1 MHz at two output sockets below the CRT screen. One output provides 0.2V,, *I % for 10: 1 probes, and 2V,, +I % are present at the other, for 100: 1 probes. When the attenuator switches are set to 5mV/cm vertical
deflection coefficient, these calibration voltages correspond to a screen amplitude of 4cm.
small insulated non-metallic screwdriver or trimming tool, the trimmer has to be adjusted slowly until the tops of the squarewave signal are exactly parallel to the horizontal graticule lines. (See Fig. above for 1 kHz.) The signal amplitude shown should be 4cm + 1.2 mm (= 3 %), During this adjustment, the signal edges will remain invisible. Adjustment at 1 MHz
Probes HZ51,52, and 54 will also allow for HF-adjustments. They incorporate resonance deemphasizing networks (Rtrimmer in conjunction with inductances and capacitors) which permit - for the first time - probe compensation in the range of the upper frequency limit of the vertical oscilloscope amplifier. Only this compensative adjustment ensures optimum utilisation of the full bandwidth, together with constant group delay at the high frequency end,
thereby reducing characteristic transient-distortion near the leading signal edge (e.g. overshoot, rounding, ringing, holes or bumps) to an absolute minimum. Using the probes HZ51, 52, and 54, the full bandwidth of the HM 604 can be utilized without risk of unwanted waveform distortion. Prerequisite for this HF-adjustment is a squarewave generator with fast risetime (typical 4ns). and low output impedance (approx. 5OQ). providing 0.2V and 2V at a frequency of approx. 1 MHz. The calibrator output of the HM604 meets these requirements when the pushbutton 1 MHz is depressed. Connect the probe (HZ51,52, or 54) to CH.1 input. Depress the calibrator pushbutton 1MHz. All other pushbuttons should be released (`out' position). Set the input coupling switch to DC, attenuator switch to 5mV/cm, and TIME/ DIV. switch to 0.1 l&cm. Set all variable controls to CAL. position. Insert the probe tip into the output socket marked 0.2V. A waveform will be displayed on the CRT screen, with leading and trailing edges clearly visible. For the HF-adjustment now to be performed, it will be necessary to observe the rising edge as well as the upper left corner of the pulse top. To gain access to the HF-compensation trimmer, the plastic cover of the probe connecting box has to be slid off after unscrewing the probe cable. The connecting boxes of the HZ51 and HZ54 contain one R-trimmer screw, each, while that of the HZ52 provides three. These R-trimmers have to be adjusted in such a manner that the beginning of the pulse
The output sockets have an internal diameter of 4.9mm to
accommodate the internationally accepted shielding tube diameter of modern Modular Probes and F-series slimline
probes. Only this type of construction ensures the extremely short ground connections which are essential for an undistorted waveform reproduction of non-sinusoidal high frequency signals.
Adjustment at 1 kHz
The C-trimmer adjustment compensates the capacitive loading on the oscilloscope input (approx. 3OpF with the HM604). By this adjustment, the capacitive division assumes the same division ratio as the ohmic voltage divider to ensure an equal division ratio for high and low frequencies, as for DC. (For 1: 1 probes or switchable probes set to 1: 1, this adjustment is neither required nor possible). A baseline exactly parallel to the horizontal graticule lines is a major condition for accurate probe adjustments. (See also `Trace Rotation TR', page M7.) Connect the probes (Types HZ51, 52, 53, 54, or HZ37) to CH.1 input. All pushbuttons should be released (in the `out' position), and all push-pull knobs pushed `in'. Set the input coupling switch to DC, the attenuator switch to 5mV/cm, and the TIME/DIV. switch to 0.2ms/cm, and all variable controls to CAL. position. Plug the probe tip into the appropriate calibrator output socket, i.e. IO:1 probes into the 0.2V socket, 100: 1 probes into the 2.OV socket.
1 kHz
incorrect
correct
incorrect
Approximately 2 complete waveform periods are displayed on the CRT screen. Now the compensation trimmer has to be adjusted. Normally, this trimmer is located in the probe head. On the 100: 1 probe HZ53, however, it is located in
the connecting box at the other end of the cable. Using a M8 604
top is as straight as possible. Overshoot or excessive rounding are unacceptable. This is relatively easy on the HZ51 and HZ54, but slightly more difficult on the HZ52. The rising edge should be as steep as possible, with the pulse top remaining as straight and horizontal as possible. On the HZ52, each of the three trimmers has a clearly
Subject to change without notice
defined area of influence on the waveform shape (see Fig.), offering the added advantage of being able to `straighten out' waveform aberrations near the leading edge.
Adjustment points of the probes
HZ51, HZ54
The adjustment sequence must be followed in the order described, i.e. first at 1 kHz, then at 1 MHz. The calibrator frequencies should not be used for timebase calibrations. The pulse duty cycle deviates from 1 : 1 ratio. Prerequisites for precise and easy probe adjustments, as well as checks of deflection coefficients, are straight horizontal pulse tops, calibrated pulse amplitude, and zeropotential at the pulse base. Frequency and duty cycle are relatively uncritical. For interpretations of transient response, fast pulse risetimes and low-impedance generator outputs are of particular importance. Providing these essential features, as well as switch-selectable output-frequencies, the calibrator of the HM 604 can, under certain conditions, replace expensive squarewave generators when testing or compensating widebandattenuators or -amplifiers. In such a case, the input of an appropriate circuit will be connected to one of the CAL.-outputs via a suitable probe. The voltage provided at a high-impedance input (I MSJ II 155OpF) will correspond to the division ratio of the probe used (10: 1 = 20mV,,, 100: 1 = also 20mV,, from 2V output). Suitable probes are HZ51, 52, 53, and 54. For low-impedance inputs (e.g. 50 Q), a 1: 1 probe can be employed which, however, must be fully terminated with a 5052 through-termination. Suitable probe types are HZ50 and HZ54. The latter must be switched to the 1: 1 position, and the HF-trimmer in the connecting box turned fullycounterclockwise. When connected to the 0.2V CAL. socket, and using the HZ50, this arrangement will provide approx. 40mV,, at 50Q circuit input, and approx. 24mV,, if the HZ54 is used. The voltages given here will have larger tolerances than 1 % since operation of a 1: 1 probe together with a 5OQ load is very uncommon. Using the 2V CAL. socket under similar conditions is only possible with the HZ54 probe. The potential obtained at the 5OQ input will then be approx. 190mV,,, but with almost twice the risetime. Accurate readings of the available input voltage can be shown directly on the HM604 when connecting a 5OQ through-termination between the BNC plug of the probe and the input of the oscilloscope.
osc.
Tz (I+)
I
(NF) T,
1
CAL.
(I-F) T,
T3 T, T,
T, (LF)
- IOnskm
T, (NF) 1 T,_: alters the middle frequencies Ti: alters the leading edge T,: alters the lower frequencies
HZ52
After completion of the HF-adjustment, the signal amplitude displayed on the CRT screen should have the same value as during the 1 kHz adjustment. Probes other than those mentioned above, normally have a larger tip diameter and may not fit into the calibrator outputs Whilst it is not difficult for an experienced operator to build a suitable adapter, it should be pointed out that most of these probes have a slower risetime with the effect that the total bandwidth of scope together with probe may fall far below that of the HM604. Furthermore, the HF-adjustment feature is nearly always missing so that waveform distortion can not be entirely excluded.
incorrect correct
incorrect
Operating Modes of the Y Amplifier
The required operating modes are selected on three pushbuttons located in the Y-Section. For Mono operation all pushbuttons should be in the out position, the instrument is then operating on Channel/only. M9 604
Adjustment 1 MHz
Subject to change without notice
For Mono operation with Channel II, the CH l/II -TRIG. l/II pushbutton has to be pressed. When the DUAL button is depressed, the HM604 is in Dualchannel operation. In this mode, the channels are displayed consecutively (alternate mode). This mode is not suitable for the display of very low frequency signals (
nal frequencies up to 120 kHz. However, above this frequency the inherent phase difference between the vertical and horizontal system makes accurate measurements difficult. In this mode, one of the sinewave signals provides horizontal deflection (X) while the other signal provides the vertical deflection (Y).
0"
35"
90"
180"
The phase angle between the two signals can be determined from the Lissajous pattern as follows:
sin cp = E cos cp =
1/ I-@
%J = arc sin f b
This simple formula works for angles less than 90", it is independent from both deflection amplitudes on the screen. Caution! If a single spot appears (both deflection voltages are missing) reduce the intensity immediately, as a high intensity setting may cause damage to the fluorescent screen of the CRT.
X-Y Operation
For X-Yoperation, the pushbutton in the X-Section marked X-Y must be depressed. The X signal is then derived from the Channe///(HOR. INP.). The calibration ofthexsignal during X-Y operation is determined by the setting of the Channel II input attenuator and variable control. This means that the sensitivity ranges and input impedances are identical for both the X and Y axes. However, the Y-POS.II control is disconnected in this mode. Its function is taken over by the X-POS. control. It is important to note that the X MAG. x10 facility, normally used for expanding the sweep, should not be operated in the X-Y mode. It should also be noted that the bandwidth of the X amplifier is approximately 5MHz (-3dB), and therefore an increase in phase difference between both axes is noticeable from 50 kHz upwards. The Y-Input signal may be inverted by using the INVERT (channel I) facility.
Dual-Trace Phase Difference Measurements
Phase comparison between two signals of the same frequency can be made using the dual-trace feature (DUAL button depressed). This method of phase difference measurement can be used up to the frequency limit of the vertical system. To make the comparison, use the following procedure: Set the Input Coupling switches to the same position, and the CH. I/II-TRIG. l/II pushbutton to the channel where the reference signal (Phase 0") is connected. Select ALT. channel switching for frequencies above 1 kHz, and CHOP. for frequencies below 1 kHz. Use probes which have equal time delay to connect the signals to the input connectors. Set the Input Attenuator switches and the CH I and CH II variable controls so that the displays are approximately equal and about five divisions in amplitude. Set the TIME/DIV. switch to a sweep rate which displays about one cycle of the waveform. Move the waveforms to the center of the graticule with the Y-P0S.I and Y-POS.II controls. Turn the Variable Time Control until one cycle of the reference signal occupies exactly 10 divisions (see next figure). Each division represents 36" of the cycle.
Subject to change without notice
X-Y Phase Measurements
The X-Y phase measurement method can be used to measure the phase difference between two signals of the same frequency. This provides a method of measurement for sigMl0 604
Figure 2 Amplitude modulated oscillation: F = 1 MHz; f = 1 kHz; m = 50 % ; UT = 28.3 mVrms.
Dual-Trace Phase Difference Measurements T = Horizontal distance foroneperiod(cm). t = Horizontal distance of zero-crossing points (cm). Assume a horizontal difference of 3 divisions (t = 3cm) and a period of 10 divisions (T = 1 Ocm), the phase difference 91 can be calculated using the following formula: or arcg, respectively. 108" =f -2~t =$ a2~~ = l.885rad
Oscilloscope setting for a signal according to figure 2: Depress no buttons. Y: CH. I; 20mV/div; AC. TIM E/DIV. : 0.2 ms/div. Triggering: NORMAL with LEVEL-setting; internal (or external) triggering. If the two values aand bare read from the screen, the modulation factor is calculated from
a- b m =a+b
resp. m = a*. 100 [%J
where a = UT (l+m) and b = UT (l-m).
Measurement of an amplitude modulation
The momentary amplitude u at time t of a HF-carrier voltage, which is amplitude modulated without distortion by a sinusoidal AF voltage, is in accordance with the equation u = U,. sinQt + 0,5m . UT - cos(S&w)t - 0,5m - UT - cos(l(r+o)t w h e r e U, S2 0 m = unmodulated carrier amplitude = 2~rF = angular carrier frequency =2nf = modulation angular frequency = modulation factor (S 1 P 100 %).
The variable controls for amplitude and time can be set arbitrarily in the modulation factor measurement. Their position does not influence the result.
Triggering and Timebase
With the LEVEL knob in locked position (turned ccw to AT position = automatic triggering), a baseline is displayed continuously even when no signal is present. In this position it is possible to obtain stable displays of virtually all uncomplicated, periodically repeating signals above 30 Hz. Adjustments of the timebase then are limited to timebase setting. With normal triggering (LEVEL knob not in AT position) and
The lower side frequency F-fand the upper side frequency F+f arise because of the modulation apart from the carrier frequency F. UT T 0,5m * UT
4
I F
4
0,5m - UT
LEVEL adjustment, triggering of time/div. deflection can be set in any point of a given signal. The triggering range which can be set with the LEVEL control depends greatly on the
amplitude of the displayed signal. If it is less than 1 div, then the range is quite small and performance of settings requires a delicate touch.
Figure 1 Amplitude and frequency spectrum for AM display (m = 50%)
F-f
F+f
The display of the amplitude-modulated HF oscillation can be evaluated with the oscilloscope provided the frequency spectrum is inside the oscilloscope bandwidth. The time
base is set so that several cycles of the modulation frequency are visible. Strictly speaking, triggering should be external with modulation frequency (from the AF generator or a demodulator). However, internal triggering is frequently possible with normal triggering using a suitable LEVEL setting and possibly also using the time variable adjustment.
Subject to change without notice
If the LEVEL control is incorrectly set, no trace will be visible.
In order to obtain a satisfactory stable display, the timebase must be triggered synchronously with the test signal. The trigger signal can be derived from the test signal itself, when internal triggering is selected, or from a frequency related signal applied to the external trigger input.
Ml1 604
Triggering can be selected on either the rising or falling edge of the trigger signal depending on whether the SLOPE +/pushbutton (next to LEVEL)is in the out or in position. In the out position, triggering from the positive-going edge is selected. The correct slope setting is important in obtaining a display when only a portion of a cycle is being displayed. With internal triggering in the Mono channel mode on the Y amplifier, the trigger signal is derived from the respective channel in use. In the Dualchannelmode, the internal trigger signal may be selected from either Channel I or Channel//using the CHMI-TRIG.I/II button; in the out position, the trigger signal is derived from Channel I. However, it is always preferable to trigger from the less complicated signal. With internalalternate triggering (ALT pushbutton in the X-Section depressed) in the DUAL channel alternate mode of the Y amplifier, the trigger voltage is derived alternately from Channel I and Channel II. This trigger mode is particularly useful when two asynchronous signs/s are being investigated. Normal triggering should be preferable in this mode. The display of one signal only is not possible on the alternate trigger mode. For exfernaltriggering, the EXT. pushbutton in the X-Section must be depressed. The sync. signal (0.05V,,-0.5VJ must then be fed to the TRIG. INP. input socket. Coupling mode and frequency range of the trigger signal are selected with the TRIG. lever switch in the X-Section for internal and external triggering, provided that the TV SEP. switch is in off position. The HM 604 has 4 coupling modes: AC, DC, LF, HF. The AC coupling mode is mainly used. DC trigger coupling is only recommended, when very low frequency signals are being investigated and triggering at a particular value is necessary, or when pulses, which significantly change in duty cycle during observation time, have to be displayed. If DC coupling is selected, it is advisable to use the normal triggering mode. In the HF coupling mode, a high pass filter is switched into the trigger amplifier. This filter cuts off the DC content of the trigger signal and the lower frequency range. In the LF coupling mode, a low-pass filter is switched into the trigger amplifier. This filter cuts off any amplifier noise and the frequency range of the trigger signal above 50 kHz. For the purpose of line triggering (TRIG. lever switch in the X-Section) to N, a (divided) secondary voltage of the power transformer is used as a trigger signal. This trigger mode is independent of the signal amplitude or display height and allows a display below the (internal) trigger threshold. Line triggering is recommended for all signals which are time-related (multiple or submultiple) to the mains/line frequency or when it is desirable to provide a stable display of a lineMl2 604
frequency component in complex waveforms. Therefore it is especially suited for the measurement of small ripple voltages from power supply rectifiers or of magnetic or static leakage fields~in a circuit. In some countries, the standard power plug has symmetrically arranged plugs (interchanging of Line and Neutral is possible). In such cases, the SLOPE +/- pushbutton may indicate the wrong polarity compared with the display (triggering with falling edge instead of rising edge). For correction, the power plug of the instrument has to be turned.
Triggering of video signals
The built-in active TV-Sync-Separator separates the sync pulses from the video signal, permitting the display of distorted video signals either in line (H = horizontal) or in frame (V = vertical) trigger mode. The TV lever switch has five positions: the OFF position is for normal operation. The TV: H+ and H- positions (horizontal= line) and the TV: V+ and V- (vertical =frame) positions are used for video triggering. In these four positions the TRIG. coupling switch and the LEVEL control (in NORM. trigger mode) are inoperative. In the TV: V+ and V- positions (frame triggering), a low-pass filter or integrating network is connected into circuit, which forms a trigger pulse sequence with frame frequency from thevertical sync pulses (incl. pre-and postequalizing pulses). When in V mode, it is possible to select field I or II by releasing or depressing FIELD l/II pushbutton. For correct video triggering, the + and - positions at V and H must be selected corresponding to the video input si