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Summary of Contents for SFG611

Page 2: ...Hz Sweep Function Generator SFG611 12MHz SWEEP FUNCTION GENERATOR SFG611 Contents Section 1 Description and Specification Section 2 Operation Section 3 Circuit Description Section 4 Maintenance CROWBO...

Page 3: ...smitted in any form or by any means electronic mechanical photocopying recording or otherwise without the prior permission of Feedback Instruments Limited 4 The Health and Safety at Work Act 1974 We a...

Page 4: ...fixed attenuators of x0 1 each give a suitable range of output level control The d c offset facility gives a unipolar capability with all com 12MHz Sweep Function Generator SFG611 SECTION 1 binations...

Page 5: ...e shot sweep facility enabling the SFG611 to be used with X Y recorders a TTL square wave output then operates as a pen lift control An effective bright trace marker gives high resolution calibration...

Page 6: ...ped Attenuator Two fixed attenuators selectable x0 1 each 12MHz Sweep Function Generator SFG611 Offset Adjustable fro n 5V through 0 to 5V giving unipolar signal capability All combinations of signal...

Page 7: ...pen lift control for X Y recorders The set max min spring return lever switch over rides the sweep triangle generator to hold the waveform at its maximum 5V or minimum OV excursion In the run conditio...

Page 8: ...standard TTL loads Termination BNC Triangular wave Amplitude 1V pk pk Impedance 50S1 Termination BNC Power Requirements Line voltage 110 220 240V 50 or 60Hz selected by external slide Consumption 25V...

Page 9: ...0 11 11 a a Q n c 311 r 3 CD a...

Page 10: ...are recommended to set the controls as follows before reading further if they wish to try out the controls as they are described 12MHz Sweep Function Generator SFG611 SECTION 2 This procedure may als...

Page 11: ...ude is set to say 6V pk pk 3V pk and 4V of offset are applied the resulting signal will oscillate between 1 V and 7V It is always possible to set every part of a waveform to be of the same polarity in...

Page 12: ...reduced tenfold The frequency of the main output waveforms can be altered from the calibrated value by the application of a control voltage This voltage may be derived from an external source or from...

Page 13: ...O SfG 611 o V JIV T 1 onnono o DOD o o DO 5Vpk manito r displays of frequency response it is recommended that an X Y oscilloscope use this voltage for X deflection fig 2 2 The sweep width control sel...

Page 14: ...the SFG611 The maximum frequency of a sweep should be set first It is simply that which is set on the normal frequency controls The minimum frequency is that frequency multiplied by a factor less tha...

Page 15: ...nge In setting up this display the oscilloscope s horizontal sensitivity may conveniently be adjusted so that the trace is just 9cm long The display scale is then 3cm per decade the graticule lines co...

Page 16: ...which greatly facilitate frequency response work when used in conjunction with an external frequency meter The latter may con veniently be driven from the auxiliary TTL output near the main output soc...

Page 17: ...ncy measured the marker should be set to mark the feature on the display Pressing the marker pushbutton will then hold the frequency of the oscillator at the value marked the marked frequency can then...

Page 18: ...not easy to tell when this sort of distortion is occurring With the SFG611 where 12MHz Sweep Function Generator SFG611 sweeping occurs in both directions the response when sweeping too fast appears a...

Page 19: ...eedback Instruments Limited 20 FEEDBACK OSFG611 0 0 t x u 0 0 t6 ODDDDD DOD 00 DD monitor r f a J I a j XY oscilloscope tifJ X Fig2 9 positive X f 1display for m oo tspot J Fig 2 10 I I I I I I I I I...

Page 20: ...upwards and to the right respectively This may I 1 I I I 12MHz Sweep Function Generator SFG611 be verified by short circuiting the system to obtain zero phase shift The display can be arranged symmet...

Page 21: ...mited p The phase angle in fig 2 12 is then given by 90 x q but since q was adjusted to equal nine divisions the phase angle becomes simply 1Op 0 l J Fig 2 12 22 display for positive X moves spot to l...

Page 22: ...I When the angle is greater than 90 then the display will be in the form of fig 2 13 In this case the angle is 180 90 x q Fig 2 13 q p 12MHz Sweep Function Generator SFG611 display for positrve X move...

Page 23: ...quencies as will often be the case in servo systems this can be found by noting the direction in which the spot traces the loop as in fig 2 14 clockwise lagging llead1ng for pos1hve X moves spot to le...

Page 24: ...ation of the oscilloscope this will brighten one half of the trace Assuming that a ve voltage brightens the trace then the phase is identified as in fig 2 15 If a ve input voltage to the Z modulation...

Page 25: ...e base Put the output waveform on to the Y plates adjust the SFG611 until the transient occupies the oscilloscope screen as shown in fig 2 16 1 The timeT where F is the frequency setting 2F The time T...

Page 26: ...a following error Ef The method illustrated in fig 2 18 displays this error as a gap between the forward and return traces For servos a velocity constant Kv is defined K where R pk to pk amplitude of...

Page 27: ...1 l CD CD 0 Pl 2 3 CD Cll r 3...

Page 28: ...n the capacitor is reproduced by a voltage follower amplifier Tr22 23 When it rises sufficiently the output of comparator AR 12MHz Sweep Function Generator SFG611 SECTION 3 goes negat1ve cutting off T...

Page 29: ...w 0 0 Vl ro V I p 3 E t c Cl ro 0 Cll t C 71 l 2 3 Cll 3 en r 3...

Page 30: ...I I I I I I I I I t I Tr25 Fig3 2 12MHz Sweep Function Generator SFG611 N Vref Tr27 Tr26 current mirror 31...

Page 31: ...via resistors providing a 50 ohm output impedance it also provides the input waveform for the output amplifier directly when triangle output is required or 32 after conversion by the sine shaper Wave...

Page 32: ...I I I I I I I I I I R162 R160 Fig3 3 12MHz Sweep Function Generator SFG611 to output stage R15S 33...

Page 33: ...ges Output Amplifier A simplified form of this is shown in fig 3 6 A signal selected by the triangle sine square switches is adjusted in amplitude by the volts control R37 From its slider there are tw...

Page 34: ...cies are fed via emitter follower Tr8 and a transmission line to the 12MHz Sweep Function Generator SFG611 emitter of Tr9 whose base is grounded by C13 The collector of Tr9 drives the output stage as...

Page 35: ...capacitors C23 to C28 switched by the frequency range setting buttons The current is variable by one or more of the frequency dial knob 36 ff the mark space ratio control function the internal sweep o...

Page 36: ...amplifier causing the emitter ofTr6 to be at V0 These potentials are applied to a resistor network which can be adjusted to provide a wide range of currents Its simplest form is obtained with the lin...

Page 37: ...s half of the variable mark space ratio control R88 In the Hz 1 0 position both halves d R88 are used Thus the current 7 to one or both of Tr6 Tr42 is reduced by a controllable amount increasing the d...

Page 38: ...the bases of Tr5 Tr6 must be such as to satisfy in Tr5 the relationship Vbe Vt In ki which applies to all the transistors where Vbe is the voltage of the base with respect to the emitter i is the 12MH...

Page 39: ...s pair of voltage input terminals When the instrument is set to run one output is derived from the AH comparator 40 after three logic inversions and the other after two inversions and the latter outp...

Page 40: ...I 12MHz Sweep Function Generator SFG611 I R12 I I I I v I I I I I I AD 4 1 _ _ I I I J I IV I I J I logic IB I I I I 1 IR22 _L I R11 I Fig 3 9 41...

Page 41: ...that the flop flop AC10 11 is cleared i e set to the state which causes a decrease in frequency The 42 frequency thus runs down at the normal set rate to its minimum value Setting the switch to trig s...

Page 42: ...diodes The influence of AG is negligible in this configuration because of its high output impedance The sweep out put is therefore now determined only by v the marker potential Sweep voltage and freq...

Page 43: ......

Page 44: ...ere is access to all the components by removal of the cover To remove it grasp one end of the carrying handle firmly and pull it outwards fig 4 1 thereby re leasing the centre cap Firm pressure is nee...

Page 45: ...m to exactly 1 0V peak to peak by adjusting R11 9 Adjust R11 7 to make the waveform symmetrical about zero 3 Connect the oscilloscope to the max end of R37 Press the square waveform selector button Ad...

Page 46: ...ero d c component Select sine wave output Adjust R153 R152 to give the same peak to peak output and zero d c com ponent 10 Connect the frequency meter to the output If not available adjust the oscillo...

Page 47: ...ile on this setting observe the triangle waveform on the oscilloscope and adjust R91 to give equal sized flats at the top and bottom of the waveform 17 Switch to lin select 10kHz to 100kHz range and s...

Page 48: ...esistor 1 metal film Resistor Ys W 100Al PWB hole carbon centres 0 3 Dia 0 1 12MHz Sweep Function Generator SFG611 Position R1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 19 20 21 25 27 28 29 31 32 34 35...

Page 49: ...meter 128 139 152 153 Front panel R13 22 24 30 37 69 88 controls I Capacitor 25V 50 rear panel C34 35 aluminium 10 electrolytic I Capacitor 20V 20 PWB hole C8 14 15 16 17 21 22 40 tantalum centres ele...

Page 50: ...ypes are not available the following types bearing ElA or Pro Electron type num bers may be used This table does not imply that the types listed are equivalents in any other situation Position C38 C12...

Page 51: ...54 Other components including mains transformer and pushbutton switches are supplied to Feedback speci fications and should be ordered through Feedback Instruments Limited Crowborough Sussex Returned...

Page 52: ...V1 _ D z...

Page 53: ..._ h _ J I 8 Q B o JI 6 c1 L___ r I r m Q y w y o r I I J J Vi LL ___ _J iiI I I _j I CiS l f 11 6 8 ltiJJ I ___ _ W GE_ f_IR___S __ L i _j 1 1J t _ 11 iii l r _ 0 11 l I f i i t r_ j LJ i_ _t _ I I Ld...

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