1309-A Oscillator, Manual
Contents
1. 2 5K 302 15K WH 8R C O9A B 42725 5 SOmv 500mv 5v e e at DIS Hare or 105F 47103 BL 203 R202 R20 n 66 5K46 65k 9 665 S20 WH BK 202R 203R 2041 206 207 R205A X R207 R206 220 620 9 eu cow 0 3 OUTPUT E R2058 X soon Es i R208 2 4 9 y 47120 X8205A 8 PLUS R206 R207 R208 FORM A J201 Contact 01 is 6002 CONSTANT IMPEDANCE ATTENUATOR BASE DIAGRAM BOTTOM VIEW BASE BASE M d Wek 7 500mv 5v COLL COLL 1 3 a 04 0501 0102 93010302 SOmve 5v e Eee P P M er de GATE que Ov SOURCE a its pos 206R 520 DRAIN _ BASE 520 SECTIONI FRONT SECTION 2 REAR ri MOS FREQUENCY IKHz NOTE UNLESS SPECIFIED I00Hz 2 IOKHz s POSITION OF ROTARY SWITCHES 5 RESISTANCE IN OHMS 027 100 SHOWN COUNTERCLOCKWISE 1000 OHMS M 1 MEGOHM KHz CONTACT NUMBERING OF SWITCHES 9 CAPACITANCE VALUES ONE AND LE EXPLAINED ON SEPARATE SHEET E coer eaten SUPPLIED IN INSTRUCTION BOOK IN MIG Aree REFER TO SERVICE NOTES IN INSTRUC 7 C KNOB CONTROL TION BOOK FOR VOLTAGES 8 Q SCREWDRIVER CONTROL he T AN 3066 540 4 RESISTORS 1 2 WATT 2 540 1 TP TEST POINT SECTION 2 RE AR SECT ON 3 FRONT ANCHOR TERMINALS USED AT OI THRU IS 120 45 APPENDIX SUPPLEMENTARY EQUIPMENT AVAILABLE Type 480 P308 Relay Rack Adaptor Set This adaptor set allows2. 4 4 6 5 0 1V CY 5 eee 1m 10 15 Adjust C302 Figure 6 3 for minimum overshoot and fastest rise time on the leading edge There should be no noticeable ringing Measure the rise time of the square wave It should be less than 100 us Output Amplitude Remove the 50 load resistor and measure the unloaded square wave output It should be at least 5 volts peak to peak Droop FREQUENCY range 10 Hz to 100 Hz FREQUENCY diali se 7s 1 Observe the square wave on the oscilloscope There should be no measurable droop or ramp off 4 THROUGH HOLES Mies R303 Figure 6 2 Top interior view of the Type 1309 A Oscillator Rill THERMISTOR UNDERNE ATH ATIII ATIO2 TPA 0104 EMITTER COLLECTOR CONNECTION 1108 POINTS FOR BATTERY 0103 EMITTER JUNCTION JUNCTION RIO5 CIO3 RII5 Figure 6 3 Bottom interior view 42 REF NO C101 C102 C103 C104 C105 C106 C107 C108 C109A 109 C110 C111 C301 C302 PARTS LIST DESCRIPTION CAPACITORS Electrolytic 15 100 10 15V Electrolytic 100 10 15V Electrolytic 15 100 10 15V Electrolytic 0 100 10 25V Trimmer 5 25 Mica 62pF 5 Ceramic 0 1uF 50V Electrolytic 2004F 4100 1095 6V Electrolytic 300HF 35V Electrolytic 3004F Electrolytic 15uF 100 10 15V Ceramic 470pF 10 Electrolytic 10 100 10 25V Trimmer 8 50pF C401A B V
3. 38 52 Current 50 to 55 mA for sine wave output 55 to 60 mA for square wave output Power approximately 2 watts minimum These requirements do not include the pilot lamp which needs 6 volts at 200 mA The source which should be externally fused with a 1 16 A fuse and equipped with an on off switch is connected to the two terminals of C501 as shown in Figure 6 3 and Figure 6 5 The normal internal ac power supply may be left intact and used in place of the external source as desired 19 TYPE 1309 OSCILLATOR SECTION 4 APPLICATIONS 4 1 GENERAL The constant output of the Type 1309 Oscillator over its wide frequency range facilitates frequency response measurements while its low hum and distortion make it very useful for amplifier distortion measurements Since the noise levels close to the fundamental are low use of the Type 1309 makes easy the measurement of amplitude modulation in magnetic recordings and the measurement of the intermodulation products in any device The square wave output allows the direct measurement of the high frequency characteristics of many devices Most of these applications are common to any sine or square wave source However the following paragraphs list specifically some of the more interesting applications of the Type 1309 which result from the syn chronization feature 4 2 SLAVED OSCILLATORS Because the EXT SYNC jack is simultaneously an input and an output connector two or mor
4. Impedance 100 or greater Digital frequency meter counter Frequency 10 Hz 100 kHz 0 1 accuracy Sensitivity 1 V rms Impedance 100 or greater The Type 1151 Digital Time and Frequency Meter is recommended The frequency accuracy of the Type 1309 is 2 The counter ac curacy should be at least 20 times this or 0 1 to prevent counter errors from entering into the measurements The one count uncertainty in a counter with a 100 kHz time base represents an error of greater than 0 1 unless the 35 TYPE 1309 OSCILLATOR measurement conditions are as follows above 1000 Hz direct frequency measurement l second counting interval below 1000Hz period measurement 10 period count Oscilloscope Bandwidth dc to 30 MHz 3 dB points Sensitivity 50 mV Impedance 100 or greater The Tektronix Type 543 543A Oscilloscope with a Type CA Plug in and Type P6000 Probe is recommended Wave Analyzer and or Distortion Meter Frequency 10 Hz 100 kHz Sensitivity 504V to 5 V v Impedance 100 or greater d The Type 1900 A Wave Analyzer and the Hewlett Packard Type 334 A Dis tortion Meter are recommended Test Oscillator Frequency 1 kHz Amplitude 1 V into 25 The Types 1309 1310 and 1311 Oscillators are recommended Load resistors 50 1 The Type 500 C Resistor is recommended 600 1 1W The Type 500 G Resistor is recommended Cables Telephone plug to
5. 1 8 IN Div FREQUENCY IN Hz Figure 4 4 The spectrum of a typical 1 kHz reference frequency signal Figure 4 5 is the spectrum of the output of a Type 1309 Oscillator syn chronized to the 1 kHz frequency of Figure 4 4 Note the significant reduction in distortion noise and hum 4 4 2 FREQUENCY MULTIPLICATION The harmonic content of the reference can be used for precise frequency multiplication since the oscillator can be synchronized to the harmonics The 22 APPLICATIONS FREQUENCY IN Hz Figure 4 5 The spectrum of the output of a Type 1309 Oscillator locked to the source of Figure 3 4 accuracy and long term stability of the submultiple reference are maintained and the oscillator output is of course sinusoidal This technique can be used with most signals because harmonics are usually present or can be easily generated 4 4 3 OTHER CONTRIBUTIONS In addition to the above capabilities the Type 1309 Oscillator also provides amplification isolation amplitude stabilization and level control Less than a volt into the high impedance EXT SYNC jack produces a full 5 volt open circuit or 10 mW into 600 ohms output The oscillator protects the reference source from short circuits and nonlinear loads The output has the same long term amplitude stability as the normal unsynchronized output and is thus free from changes in
6. 1009 595 1 2w Composition llkQ 595 1 2w Composition 4 7kQ 5 1 2w Film 26 7MQ 1 1w Film 26 7MQ 41 lw Film 2 67MQ 1 1 2w Film 2 67MQ 19 1 2w Film 267kQ 1 1 2w Film 267kQ 195 1 2w Film 26 7kQ 1 1 2w Film 26 7kQ 41 1 2w Composition 472 5 lw Composition 2 7kQ X595 1 2w PART NO 6100 3225 6040 0800 6100 3105 6100 3125 6100 3475 6100 3515 6100 3275 6100 2335 6100 3155 6100 1565 6741 2023 6040 0300 6100 3105 6100 1275 6100 2565 6100 2105 6100 1105 6100 2245 6100 1515 6450 0665 6450 1665 6450 2665 6450 3604 6045 1100 6100 1625 6100 1625 6100 0365 6100 2125 6100 3155 6040 0500 6100 3105 6100 3225 6100 1625 6100 2205 6100 1105 6100 3115 6100 2475 6550 5267 6550 5267 6450 4267 6450 4267 6450 3267 6450 3267 6450 2267 6450 2267 6110 0475 6100 2275 Figure 6 4 Etched board assembly of the Type 1309 A Oscillator NOTE The number appearing on the etched board is the number of the board only without circuit nents When ordering a new etched board assembly use the following part number 1309 2700 WIEN BRIDGE e AC 8 0C OUTPUT LEVEL R408 26 7K p 100 8406 10 267K 105F 2058 Ra R404 540 2 67M 724 204RR402 26 7M 100 223 IW 03F 10 Ca OFF FREQUENCY DIAL OFF t 40
7. 3 Sync out Disconnect the test oscillator from the EXT SYNC jack and connect the voltmeter in its place The sync out amplitude should be approx 1 5 V rms 6 7 9 OUTPUT RESPONSE Connect the 600 ohm load resistor and the voltmeter to the OUTPUT terminals and check as follows TABLE 6 6 OUTPUT RESPONSE FREQUENCY Range Dial Output Voltage rms Setting Setting 100Hz 1kHz 10 1kHz Set OUTPUT controls for exactly 2 5V 100Hz 1kHz 5 500Hz 2 55 to 2 4V 100Hz 1kHz 1 100Hz 2 55 to 2 4V 10Hz 100Hz 1 10Hz 2 55 to 2 4V 1kHz 10kHz 10 10kHz 2 55 to 2 4 V 10kHz 100kHz 10 100kHz 2 55 to 2 4V 6 7 10 CALIBRATION PROCEDURE FOR SQUARE WAVE OUTPUT SYMMETRY FREQUENCY range 10 Hz 100 Hz FREQUENCY dial 10 OUTPUT switch s US V OUTPUT control soies cw Adjustment of R503 Connect the 50 0 load resistor and the wave analyzer v the output of the Type 1309 Measure the second harmoni c component 2 kHz of the square wave Adjust R503 Figure 6 3 to minimize this component 40 SERVICE AND MAINTENANCE SQUARE WAVE CHECKS Rise time adjustment FREQUENCY range 10 kHz 100 kHz FREQUENCY dial 10 cue etches Ll 5 V OUTPUT eesttol eue cw With the oscilloscope observe the output of the Type 1309 into the 50 load resistor Set the scope controls as follows Dual trace operation MODE one channel only
8. oscillators Square Wave Voltage Greater than 5 V peak to peak open circuit De coupled output Impedance 600 0 Rise Time Under 100 ns into 50 Q Typically 40 ns at full output Control Minimum of 20 dB continuously adjustable attenuator only Symmetry 2 over whole frequency range GENERAL Terminals Two Type 938 Binding Posts one grounded Accessories Supplied Type CAP 22 Power Cord spare fuses Accessories Available Type 1560 P95 Adaptor Cable telephone plug to Type 274 M Double Plug for connection to synchronizing jack relay rack adaptor set Power Required 100 to 125 V 200 to 250 V 50 to 400 Hz 6 W Mounting Convertible bench cabinet Dimensions Width 814 height 6 depth 8 inches 210 by 155 by 210 mm over all Net Weight 634 3 1 kg loHz 20 50 100 200 500 Ik 2 5 20 50 _ 100 FREQUENCY Typical harmonic distortion vs frequency of Type 1309 sine wave output OSCILLATOR GENERAL RADIO 10 Hz 100 kHz ui Hy CONCORD MASS USA D TYPE GERAL 124 7 500uv 5v s ru SONY SV P P Suys OUTPUT 85 Figure 1 1 The Type 1309 A Oscillator INTRODUCTION SECTION 1 INTRODUCTION 1 1 PURPOSE The Type 1309 Oscillator is a general purpose source of sine and square waves for laboratory or production use It features a wide audio frequency range an accurate output attenuator low distortion hum and noise high
9. Quebec Canad Telephone 514 737 3673 General Radio Company Overseas 8008 Zurich Switzerland General Radio Company U K Limited Bourne End Buckinghamshire England Representatives in Principal Overseas Countries Printed in USA INSTRUCTION MANUAL TYPE 1309 A OSCILLATOR Form No 1309 0100 B ID 1227 July 1966 Copyright 1962 by General Radio Company 8 West Concord Massachusetts USA GENERAL RADIO CO M P AUN WEST CONCORD MASSACHUSETTS USA TABLE OF CONTENTS Section L INTRODUCTION lt e wo s CUN dw y wA c SU a verc yi ue qe pie er Dee DescPIDLIOD Wen ty SU ce e dece 0 0 NEN SO pO 1 3 Controls and GonnectotfS e 2 1 4 Accessories Supphed Sat 9 of W rss Ane Section 2 INSTALLATION lt lt EC OE E E Nene PORE 2 SS e 2 2 Rack Mounting m gt 2 9 rowers Congectlon o lt ims de Section OPERATING PROCEDURE I v Q lt s 2 0 6 Ju uNotinabl OUeratton Wine eles T S Me Nine 2 9 w 9 2 PS80186 AGJUSINICNES 3 83 Output Gonnectlon s s s gt s lt lt lt lt DE mem gina SP M NET 9 4 v e cew 2 s 2 an eus cm rere 3 9 Squate Wave Outp bt p C Ls lt
10. ew 4 0 Synearonization JACK ues vox G Q 6 Section 4 APPLICATIONS T coe eee Os ANM S m 00 15 0 0 4 1 General lt lt us ae ur 4 2 Saved lt lt w 4 eee s 6 4 3 Waveform Synthesizer e o e s 4 4 Accurate Frequency Source with Clean es Shortable Output 4 5 Tracking Narrow Band Filter e 2 o s s e 4 6 Amplitude Modulated Oscillator E eu dri ct t yc SI S vu 60 0 E Section 5 PRINCIPLES OF OPERATION s v e 99509 Sl o Gelleral eos rene unen tote ts ak a 5 2 The Wien bridge Oscillator s cce lt o oe 23 5 3 The Oscillator Amplifier Ge Be ame ET 5 4 5 4 The Square Wave Generating Circuit ete Sy a co Lo Ne oO igi oe poser ve a 7150 section 6 SERVICE MAINTENANCE G 22 5 Geb Warta EE UNDE 40 4 6 2 o os Seal ere of cote Bol ete 36 6 3 Access to Components 6 ure NET 6 4 Minimum Performance Specifications el m s Fee 6 5 TroublesShooting Notes a e bcs lt s w eje 2 4 2 65 6 6 Amplifier Open Loop Testing s s
11. s sie e s a s w ss ei 6 4 Calibration Procedure 4 s 5 v e 7 4 We ee FAR ESERI en NIE e Mrs APPENDIX Renee Malis Pav go qi A SPECIFICATIONS FREQUENCY Range 10 Hz to 100 kHz in four decade ranges Control Continuously adjustable main dial covers range in 1 turn vernier in 414 turns Accuracy 2 Synchronization An external reference signal can be introduced through phone jack to phase lock oscillator One volt input provides 3 locking range Frequency dial can be used for phase adjustment OUTPUT Sine Wave Power 10 mW into 600 9 load Voltage 5 0 V 5 open circuit after warmup Impedance 600 Q One terminal grounded Control Minimum of 20 dB continuously ad justable and 60 dB step attenuator 20 0 2 dB per step Also a zero volts output position with 600 2 output impedance maintained Distortion Less than 0 0595 from 200 Hz to 10 kHz increasing to less than 0 25 at 10 Hz and 100 kHz open circuit or 600 Q Frequency Characteristic 2 over whole frequency range for loads of 600 9 or greater Hum Less than 50 uV regardless of attenuator setting 0 001 of full output Synchronization High impedance 12 kQ con stant amplitude output of approximately 1 5 volts for use with external counter for trigger ing an oscilloscope or for synchronizing other
12. setting of the oscillator is changed there will be transient changes in amplitude and phase for a few seconds before the oscillator returns to steady state synchronization This time constant is caused by the thermistor amplitude regulator as it readjusts to the different operating conditions The thermistor is sensitive only to changes in average values of frequency or amplitude where the aver aging time is in the order of seconds Hence frequency modulated and ampli tude modulated sync signals which have a constant average value of fre quency and amplitude over a period of 2 second or less are not affected by this time constant For slow changes in frequency or amplitude the lock range and the capture range are the same i e the frequency or amplitude at which the os cillator goes from the synchronized state to the unsynchronized state is the same as when it goes from the unsynchronized state tothe synchronized state Synchronization is truly phase lock ing that is it maintains a constant 5 90 phase difference between the sync 5 input and the oscillator output The 2 phase difference is 0 when the s dial frequency is identical to the 25 sync frequency and approaches 190 g as the frequency approaches the Bao limits of the locking range Note Lower LIMIT RN Geen that the phase difference is also a LOCK RANGE rms LOCK RANGE INPUT FREQUENCY function of the amplitude of the sync signal because
13. stability and accuracy rapid transition highly symmetrical square waves plus a synchronizing feature which allows such varied uses as filtering level ing frequency multiplying jitter reducing and slaving 1 2 DESCRIPTION The all solid state Type 1309 consists of a Wien bridge oscillator a square wave generating circuit a constant impedance 600 ohms step attenu ator and a power supply 1 3 CONTROLS AND CONNECTORS The controls and connectors on the Type 1309 Oscillator are listed in Table 1 1 TYPE 1309 OSCILLATOR TABLE 1 1 CONTROLS AND CONNECTORS Reference Figure 1 2 Name Type Function EXT SYNC Input output telephone jack For introducing a syn chronizing or phase locking signal from an external source or for providing a synchronizing signal independent of the output level to an oscilloscope counter or another oscillator 2 FREQUENCY Five position rotary Combination power switch switch and frequency range switch 3 FREQUENCY Continuously adjustable Used with FREQUENCY dial range switch to set out put frequency 4 FREQUENCY Continuously adjustable Fine frequency control vernier 4 25 1 for FREQUENCY dial 5 OUTPUT Six position rotary A 60 dB 20 dB per step larger con switch step attenuator and out centric switch put signal selector OV position removes oscillator output but maintains 600 output impedan
14. than 0 25 10 Hz Change the FREQUENCY range to 10 Hz 100 Hz and the FREQUEN CY dial to 1 10 Hz Measure the second and third harmonic distortion 20 Hz and 30 Hz total harmonic distortion must be less than 0 25 These measurements may also be made with a distortion meter 6 7 7 HUM FREQUENCY range 1 kHz 10 kHz FREQUENCY dial 1 1 kHz OUTPUT s 500 mV OUTPUT controle uum a fully cw Open circuit hum Keep the wave analyzer connected to the OUTPUT termi nals and measure the hum at 60 120 and 180 Hz total hum must be less than 0 01 total hum N hum at 60 Hz hum at 120 Hz hum at 180 Hz 6 7 8 SYNCHRONIZATION FREQUENCY range 100 Hz 1 kHz FREQUENCY dial 10 1 kHz OUTPUT Switch 4 5v OUTPUT control ax fully cw Sync in Disconnect the wave analyzer from the OUTPUT terminals and con nect a counter in its place Connect the output of another oscillator test 39 TYPE 1309 OSCILLATOR oscillator to EXT SYNC jack and set the test oscillator for 1V rms of exactly 1 kHz Very slowly increase the FREQUENCY dial setting of the Type 1309 until it drops out of sync counter reading changes from 1 kHz to some higher frequency Reduce the output amplitude of the test oscillator to below 50mV rms or turn its power switch off and note the counter reading free running frequency of the Type 1309 must be greater than 1030 Hz 1 kHz
15. the oscillator to the line via the 3 wire power cord supplied The third wire of the power cord grounds the instrument frame The power requirement of the Type 1309 is 6 watts For a discussion of the power connection of the instrument as it affects hum refer to paragraph 3 3 OPERATING PROCEDURE SECTION 3 OPERATING PROCEDURE 3 1 NORMAL OPERATION To use the Type 1309 Oscillator as a source of internally generated sine or square waves a Set the FREQUENCY range switch to the desired frequency range and the FREQUENCY dial to the desired frequency e b Selection of the output signal 1 For sine wave output set the OUTPUT switch to one of the center four positions the number corresponding to a position indicates the maximum voltage attainable at that position and adjust the OUTPUT control for the exact voltage required 2 For square wave output set the OUTPUT switch in the fully clock wise position and adjust the OUTPUT control for the voltage required 3 For no output with 600 ohms output impedance maintained set the OUTPUT switch in the OV position This position enables the oper ator to avoid the transients associated with turning the oscillator on and off and makes zero output possible with no disturbance of the OUTPUT control 3 2 PRECISE ADJUSTMENTS 3 2 1 FREQUENCY To set the frequency of the Type 1309 with an accuracy better than the t 2 accuracy obtainable with the FREQUENCY dial use of a fr
16. the output level of the reference source The oscillator provides adjustable output levels which are kept constant auto matically with changes in frequency 4 5 TRACKING NARROW BAND FILTER 4 5 1 JITTER OR INCIDENTAL FM REDUCTION Although the short term stability or jitter of the synchronized oscillator can not be better than when it is free running it can be better than the source which it is synchronized In this respect it behaves as a phase locked oscillator or automatic phase control APC oscillator Or to express it differently it behaves as a tracking narrow band filter to reduce short term instability See D D Weiner and B J Leon The Quasi Stationary Response of Linear Systems to Modulated Waveforms Proceedings of the IEEE Vol 53 June 1965 pp 564 to 575 and references Harold T McAleer A New Look at the Phase Locked Oscillator Proceedings of the IRE Vol 47 pp 1137 to 1143 June 1959 GR Reprint No 79 23 TYPE 1309 OSCILLATOR The selectivity of the filter is a function of the input sync signal and the tracking mechanics have a time constant in the order of a second The effective bandwidth to small frequency perturbations or small fm deviations is related to the lock range as it is in conventional APC oscillators i e the lock range produces the 3 dB cutoff frequency of an equivalent low pass filter Since the lock range is a linear function of the sync signal amplitude the e
17. volts Often the amplitude of a frequency component relative to the amplitude of the frequency of oscillation is of greater interest than the absolute ampli tude Figure 3 18 shows this response for three different input amplitudes Notice thatthe apparent selectivity or Q in this relative response is a function of the input amplitude This is because the output at the frequency of oscil lation remains constant while the output at other frequencies varies with the input amplitude 3 6 5 SYNCHRONIZATION OF SQUARE WAVE OUTPUT WITH EXTERNAL SIGNAL The square waves produced by the Type 1309 can be synchronized to an external signal in the same manner as can sine waves The internal oscil lator locks on to the signal at the EXT SYNC terminals in the manner de scribed above and the resulting sine wave triggers the square wave generator to produce a synchronized signal Thus a synchronous output signal whose shape and amplitude is independent of the shape of the input signal is gener ated This characteristic will prove useful in for instance the generation of harmonics of the original signal 18 OPERATING PROCEDURE 0 2 05 07 10 2 0 50 100 FREQUENCY NORMALIZED INPUT DIAL FREQUENCY Figure 3 18 Frequency response of the Type 1309 A for three different inputs 3 6 6 BATTERY OPERATION The Type 1309 can be operated from any external dc source including batteries The source requirements are Voltage
18. 0 1090 8210 1114 8210 1047 8210 1040 8210 1114 8210 1114 8210 1040 7890 4210 7890 4200 7910 0831 0745 4380 43 44 REF NO R101 R102 R103 R104 R105 R106 R107 R108 R109 R110 R111 R112 R113 R114 R115 R116 R117 R118 R119 R201 R202 R203 R204 PARTS LIST cont DESCRIPTION RESISTORS Composition 22kQ 5 1 2w Potentiometer composition 25kQ 20 BIAS Composition 10kQ 5 1 2w Composition 12k 5 1 2w Composition 47kQ 5 1 2w Composition 51kQ 595 1 2w Composition 27kQ 5 1 2w Composition 3 3kQ 5 1 2w Composition 15kQ 595 1 2w Composition 5609 5 1 2w Thermistor Potentiometer composition 5002 20 Composition 10 5 1 2w Composition 2702 45 1 2w Composition 5 6kQ 5 1 2w Composition lkQ 5 1 2w Composition 1009 595 1 2w Composition 2 4kQ 5 1 2w Composition 5100 5 1 2w Film 6650 1 1 2w Film 6 65kQ 1 1 2w Film 66 5kQ 1 1 2w Film 604kQ 4195 1 2w R205A B Potentiometer composition OUTPUT R206 R207 R208 R301 R302 R303 R304 R305 R306 R307 R308 R309 R310 R401 R402 R403 R404 R405 R406 R407 R408 R501 R502 control Composition 6202 5 1 2w Composition 6202 5 1 2w Composition 362 5 1 2w Composition 1 2kQ 5 1 2w Composition 15kQ 5 1 2w Potentiometer composition 2 5kQ 20 SYMMETRY Composition 10kQ 595 1 2w Composition 22kQ 5 1 2w Composition 6202 5 1 2w Composition 2 0kQ 5 1 2w Composition
19. 0 dB step attenuator or in the 5 V p p square wave position to drive a modified high speed Schmitt circuit which generates a very fast less than 100 ns rise time square wave The square wave is dc coupled to the output through the 0 20 dB adjustable attenuator The EXT SYNC jack connects to the negative feedback loop of the Wien bridge oscillator DIFFERENTIAL WIEN BRIDGE AMPLIFIER SCHMITT CIRCUIT a 60 dB STEP ATTENUATOR 20 dB VARIABLE ATTENUATOR OUTPUT 1309 2 Figure 5 1 Block diagram of the Type 1309 low distortion oscillator 5 2 THE WIEN BRIDGE OSCILLATOR The oscillator circuit is shown in simplified form in Figure 5 2 The Wien bridge can be thought of as consisting of two parts a frequency deter mining network CA and Rp which supplies positive feedback to sustain oscillation and a voltage divider R1 and R2 from which is taken 27 1309 OSCILLATOR negative feedback to stabilize the amplitude The frequency determining net work has the following transfer function f where EIN 1 fo 5 R Ra Rp At the frequency fo this function equals 1 3 This frequency is determined by the ganged variable capacitors CA and Cp and one of four pairs of pre cision metal film resistors and Rp selected by the FREQUENCY RANGE switch The resistiv
20. 12 OPERATING PROCEDURE other circuits see Figure 3 10 The output impedance is 600 ohms at all times during the square wave cycle and the voltage is variable from 0 5 to 5 volts peak to peak by the constant impedance bridged T attenuator Figure 3 10 Direct coupled 10 Hz square wave has flat top Horizontal scale 50 ms div d IOms cm 3 5 2 SYMMETRY The square wave generator is triggered by the sine waves produced by the oscillator It has therefore the same frequency accuracy and stability The waveform is symmetrical within 2 over the whole frequency range The transitions take place at the zero crossing of the sine wave If for a particular application non symmetrical pulses are required the internal SYMMETRY control R303 Figure 3 11 can be adjusted to trigger on a point on the sine waveform other than the zero crossing Duty ratios of down to about 20 are possible For a more detailed explanation of the function of this control refer to paragraph 5 4 Figure 3 11 The SYMMETRY control of the square wave gen erating circuit For instruc pr tions on access to components refer to paragraph 6 3 R303 3 5 3 RISE TIME The transitions times of the square waves are very fast less than 100 ns into 50 Figure 3 12a Still faster transitions are possible at full output and higher frequencies The rise time is typically less than 40ns into 50 Q at full ourput and 10 kHz The compromise betw
21. 38 U R401 26 7M 190 404 C 304F R403 7 uy 1 kH b 7 ATHS 2077 _ op FRAME 2 2 RIIO 100 KHz 406R 1407 I00kHz 5607 cro 555 26m 68 5 25 47107 9V 1 C10 5028 Spf 300yF n PIAS CY lt 20 wv p p r 750 GN I 5 P501 5 up NJ DIA LINE 106 200 125 250 50 400Nz 432V BIAS GANGED TO RANGE SWITCH S40 POWER SUPPLY AMPLIFIER AC 8 DC FEEDBACK 115 5 6K Figure 6 5 Schematic diagram of the Type 1309 A Oscillator 4 RUE IK of the section respectively otary switch sections are shown as viewed from the panel end of the shaft The first digit of the contact number refers to the section The section nearest the panel is 1 the next section back is 2 etc The next two digits refer to the contact the first position clockwise from a strut screw usu ally the screw above the locating key and the other contacts are numbered sequentially 02 03 04 etc proceeding clockwise around the section A suffix F or R indicates that the contact is on the front or rear 326 SYMMETRY cw R303 T32V R308 100 SCHMITT CIRCUIT s 30 5 V 8307 2K R309 HK
22. 501 The base voltage of Q501 is held fixed at 33 volts by Zener diode CR503 the emitter therefore is held at a fixed voltage The power transformer T501 is wired so that either a 115 volt or a 225 volt ac power source can be used depending on the setting of S502 the LINE switch 30 SERVICE AND MAINTENANCE SECTION 6 SERVICE AND MAINTENANCE 6 1 WARRANTY We warrant that each new instrument manufactured and sold by us is free from defects in material and workmanship and that properly used it will perform in full accordance with applicable specifications for a period of two years after original shipment Any instrument or component that is found with in the two year period not to meet these standards after examination by our factory Sales Engineering Office or authorized repair agency personnel will be repaired or at our option replaced without charge except for tubes or batteries that have given normal service 6 2 SERVICE The two year warranty stated above attests the quality of materials and workmanship in our products When difficulties do occur our service engineers will assist in any way possible If the difficulty cannot be eliminated by use of the following service instructions please write or phone our Service De partment see rear cover giving full information of the trouble and of steps taken to remedy it Be sure to mention the serial and type numbers of the in strument Before returning an instrume
23. 98 1 02 V Square wave Rise time 1kHz 10kHz lt 100 05 into 500 Symmetry 100Hz 1kHz 2 48 52 duty ratio on scope trace or less than 6 2nd harmonic component to funda mental 100Hz 1kHz gt 5Vp p 32 SERVICE AND MAINTENANCE 6 5 TROUBLE SHOOTING NOTES Tables 6 2 and 6 3 offer means of isolating the more straight forward difficulties that might occur in the Type 1309 A Additional troubleshooting information is contained in the Calibration Procedure paragraph 6 7 and on the schematic diagram Figure 6 5 In all cases except total failures such as a blown fuse first check the power supply voltages and dc operating level proper operation These must be correct for NOTE Always allow a 30 minute warmup before making any final adjustments TABLE 6 2 SPOT CHECK OF IMPORTANT VOLTAGE LEVELS SUPPLY Power DC bias VOLTAGE 1651 POINT 32 VDC Emitter 0501 80 YV DECA TPA TABLE 6 3 TROUBLE SYMPTOMS AND THEIR CAUSES See Figures 6 2 through 6 5 for component locations Inaccurate frequency Excessive distortion Excessive hum Poor response Instability or excessive noise 10kHz 100kH range C105 misadjusted refer to paragraph 6 7 5 for adjustment procedure One range only R or R for that range Lower ranges Dirt grease or high humidity may have affected R or frequency will be too high All ranges or or improper frequency adjustments refer to paragr
24. OPERATING INSTRUCTIONS TYPE 1309 A OSCILLATOR G E NER AL RADIO COMPANY B GENERAL RADIO COMPANY WEST CONCORD MASSACHUSETTS 01781 617 369 4400 617 646 7400 SALES ENGINEERING OFFICES NEW ENGLAND 22 Baker Avenue West Concord Massachusetts 01781 Telephone 617 646 0550 METROPOLITAN NEW YORK Broad Avenue at Linden Ridgefield New Jersey 07657 Telephone N Y 212 964 2722 N J 201 943 3140 SYRACUSE Pickard Building East Molloy Road Syracuse New York 13211 Telephone 315 454 9323 PHILADELPHIA Fort Washington Industrial Park Fort Washington Pennsylvania 19034 Telephone 215 646 8030 WASHINGTON AND BALTIMORE 11420 Rockville Pike Rockville Maryland 20852 Telephone 301 946 1600 ORLANDO 113 East Colonial Drive Orlando Florida 32801 Telephone 305 425 4671 Repair services are available at these district offices CHICAGO 6605 West North Avenue Oak Park Illinois 60302 Telephone 312 848 9400 C CLEVELAND 5579 Pearl Road Cleveland Ohio 44129 Telephone 216 886 0150 LOS ANGELES 1000 North Seward Street Los Angeles California 90038 Telephone 213 469 6201 SAN FRANCISCO 626 San Antonio Road Mountain View California 94040 Telephone 415 948 8233 DALLAS 2600 Stemmons Freeway Suite 210 Dallas Texas 75207 Telephone 214 637 2240 TORONTO 99 Floral Parkway Toronto 15 Ontario Canada Telephone 416 247 2171 MONTREAL 1255 Laird Boulevard Town of Mount Royal
25. T f T f Yr This means for example that a transition time of 50 ns would appear as a transition time of 70ns if displayed on an oscilloscope with a 50 ns rise time 3 6 SYNCHRONIZATION JACK 3 6 1 GENERAL A telephone jack EXT SYNC J103 is located on the left hand side of the oscillator This is an input output connector and is used to connect a signal to the oscillator or to take one from it 14 OPERATING PROCEDURE There are three important characteristics associated with the use of the EXT SYNC feature 1 Output characteristic 2 Input synchronizing or phase locking characteristic 3 Input frequency selectivity or filtering characteristic 40 EXTUSYNG 5 SHIELDED LEADS OR COAXIAL CABLE 7T 30 pF PER FOOT 3 6 2 OUTPUT CHARACTERISTIC A nominal 1 5 volt rms output de signal behind 12 is available prat from the EXT SYNC jack The level of this sync output signal is inde pendent of the LEVEL control or the front panel OUTPUT load One side of the sync output is grounded as shown in Figure 3 14 and the signal is in phase with the front panel OUTPUT The sync output will drive any size load without increasing oscillator distortion However only high impedance loads are recommended where full frequency accuracy is required The worst case load a short circuit will decrease the frequency 1 or 2 Stray capacitance of most shielded leads or coaxial cables is about 30 pF p
26. TH CLEAN HIGH SHORTABLE OUTPUT One obvious application for the sync capability is to lock one or more oscillators to a reference frequency for higher accuracy and greater long term stability With the oscillator synchronized its accuracy and long term sta bility will be identical with the reference short term stability or jitter will be the same as if the oscillator were free running See Figure 4 3 A Type 1309 is locked to the output of a Type 1161 A7C Coherent Dec ade Frequency Synthesizer used here as the reference frequency source The oscillator increases the 2 volt output of the synthesizer and reduces the already low harmonic content for a precision frequency modulation experiment 21 1309 OSCILLATOR Figure 4 3 The 1309 Oscillator being synchronized with the Type 1161 A7C Coherent Decade Frequency Synthesizer The frequency of 31 063 kHz when used to modulate an fm generator pro duces a null in the carrier for a 75 000 kHz frequency deviation The advantages of this arrangement accrue from the output character istics of the oscillator listed in the following paragraphs 4 4 1 DISTORTION AND HUM REDUCTION The frequency selectivity of the synchronized oscillator reduces dis tortion and hum in the reference source For example Figure 4 4 below is the spectrum of a typical 1 kHz sinu sodial frequency reference signal derived by division from a crystal oscil lator HORIZONTAL SCALE
27. aph 6 7 5 for ad justment procedure DC bias improper adjust R102 for 18V at TPA Power supply not regulating properly Output varies with frequency R111 thermis tor or grossly improper frequency adjust ments refer to paragraph 6 7 5 for adjustment procedure Dust between plates of C401 or wiper dirty or otherwise making poor contact 33 TYPE 1309 OSCILLATOR 6 6 AMPLIFIER OPEN LOOP TESTING The amplifier uses a large amount of ac feedback so that trouble at any one point in the circuit will manifest itself at most other points For this reason it may be difficult to isolate a failure under closed loop conditions therefore the following open loop test is recommended a 9 Unsolder the lead to AT111 on the etched board and unsolder one end of the thermistor R111 to open the ac feedback path see Fig ure 6 4 Set the controls as follows FREQUENCY range 10 kHz 100 kHz FREQUENCY dial 1 10 kHz OUTPUT switch 5M OUTPUT control fully cw Apply 60 mV p to p 1 kHz signal to the EXT SYNC jack J401 Trace the signal through the amplifier with an oscilloscope using a short low capacitance high impedance probe to prevent spurious oscillation The voltages observed should agree with those of Table 6 4 and the wave forms should all be sine waves 34 TABLE 6 4 OPEN LOOP VOLTAGES AND WAVEFORMS IN THE OSCILLATOR AMPLIFIER AT109 AT110 0101 drain and source Junction o
28. ariable Air 630pF FREQUENCY C402 C403 C404 C405 C501A C501B C502A C502B CR301 CR302 CR303 CR501 CR502 CR503 F501 1201 1202 1401 501 PL501 Q101 Q102 Q103 Q104 Q301 Q302 Q501 S201 S401 S501 S502 T501 Trimmer 5 5 18pF Trimmer 5 5 18pF Mica 39pF 5 Ceramic 1 2 5 Electrolytic 200HF Electrolytic 200HF Electrolytic Electrolytic 300uF 50V 35V DIODES High speed Type 1N625 Zener Type 1N971B High speed Type 1N625 Rectifier Type 1N3253 Rectifier Type 1N3253 Zener Type 1N973B MISCELL ANEOUS FUSE 0 125A 3AG Slo Blo JACK Jack top binding post OUTPUT JACK Jack top binding post Ground JACK Phone jack two contact EXT SYNC PILOT LIGHT 6V 200mA PLUG 3 terminal power TRANSISTOR Type 147 field effect TRANSISTOR Type 2N3905 TRANSISTOR Type 2N2714 TRANSISTOR Type 2N697 TRANSISTOR Type 2N3905 TRANSISTOR Type 2N3905 TRANSISTOR Type 2N697 SWITCH 6 position rotary OUTPUT SWITCH 6 position rotary FREQUENCY SWITCH power OFF part of S201 SWITCH slide LINE TRANSFORMER Power PART NO 4450 3700 4450 3700 4450 3700 4450 3800 4910 1150 4700 0364 4403 4100 4450 2610 4450 2400 4450 3700 4404 1478 4450 3800 4910 1170 1210 4000 4910 2041 4910 2041 4640 0200 4400 0120 4450 5591 4450 2400 6082 1012 6083 1049 6082 1012 6081 1001 6081 1001 6083 1036 5330 0450 0938 3000 0938 3000 4260 1260 5600 1001 4240 0600 821
29. ce for noise measurements 6 OUTPUT Continuous rotary A constant impedance smaller con control bridged T attenuator centric con which sets output level trol over a 20 dB range between the steps selected by the OUTPUT switch 7 OUTPUT inch spaced binding Lower terminal grounded 600 2 post pair to chassis Refer to paragraph 3 3 for infor mation on ungrounded operation Not Power input Three terminal male For connection to power shown on rear connector line panel Not LINE Slide switch Selects transformer con shown switch nections for input voltages as indicated by the as sociated legend OSCILLATOR GENERAL RADIO uM 2 Y CONCORD MASS UGA E17 P NM 500uv 5v s FREQUENCY 7 tkHz 10 kHz 1 gt Sex z y L OFF 72 51 Figure 1 2 Controls and Connectors on the Type 1309 1 4 ACCESSORIES SUPPLIED The accessories supplied with the Type 1309 Oscillator are listed in Table 1 2 ACCESSORIES Item Part Number Instruction book 1309 0100 Power cord 3 wire 4200 9622 Fuses 2 0 25 A for 115 V operation or 5330 0700 0 125 A for 230 V operation 5330 0450 For a description of supplementary equipment available for use with the Type 1309 refer to the Appendix 1309 OSCILLATOR SECTION 2 INSTALLATION 2 1 ENVIRONMENT The Type 1309 is designed to operate in locations with ambient temper atures f
30. double plug The Type 1560 P95 Cable is recommended 6 7 3 POWER SUPPLY and BIAS VOLTAGES Connect the Type 1309 to an ac line via a metered adjustable auto transformer and set the transformer for 115 V output Set the Type 1309 con trols as follows FREQUENCY range 100 Hz 1 kHz FREQUENCY dial 10 1 kHz V OUTPUT switch s 5V OUTPUT control fully cw 36 SERVICE AND MAINTENANCE Power Supply Connect a voltmeter to the emitter of Q501 Voltage should be 32 2 volts dc If not check CR503 and replace if necessary Bias Connect a voltmeter to TPA and adjust R111 for 18 V dc Ripple Connect the oscilloscope to the emitter of Q501 and check ripple at 100 115 and 125 V line must be less than 10 mV p to p Allow a 30 minute warmup then recheck the adjustment of R111 6 7 4 OUTPUT LEVEL FREQUENCY range 100 Hz 1 kHz FREQUENCY dial 10 1 kHz OT ser TN OUTPUT control v fully cw Maximum output Connect a voltmeter to the OUTPUT terminal and adjust R112 for 5 V rms The instrument should be on for at least 30 minutes before this adjustment is made OUTPUT control operation Vary the OUTPUT control over its full range the output level must change smoothly If it does not the OUTPUT potentio meter R205 is noisy and should be replaced 6 7 5 FREQUENCY FREQUENCY range h 1 kHz 10 kHz FREQUENCY dial 1 1 kHz OUTPUT switch LS reis 55V OUTPUT conttol son
31. du lation sidebands fall outside the passband of the oscillator The reduction can be calculated from Figure 3 18 For example we wish to determine the reduction in amplitude modulation of a 0 1 volt 10 kHz 24 APPLICATIONS signal which has 10 amplitude modulation at 1 kHz 5 or 0 005 im each sideband The signal is applied to the EXT SYNC jack of the Type 1309 the output of the Type 1309 is 5 volts and from the graph the gain at 9 kHz and at 11 kHz is 15 7 amplitude of sidebands FUE 15 7 x 005 15 7 x 005 x 100 3 14 ik total amplitude 5 Figures 4 7a and 4 7b show examples of am reduction Figure 4 7 One example of a m reduction a 10 kHz signal modulated at 500 Hz and applied to EXT SYNC jack b Reduction in a m in the output of the oscillator locked to the signal above 4 6 AMPLITUDE MODULATED OSCILLATOR If the oscillator is operated outside of the lock range the sync signal will beat with the oscillator frequency and produce an audio frequency ampli tude modulated output The modulation will be approximately sinusoidal for modulation levels up to about 10 This arrangement is not ideal but it does provide amplitude modulated signals in the audio range where normally they are not conveniently obtain able Modulated outputs of this type can be used to measure the effects of incidental a m on other measurements and to provide a modulated source to reduce meter friction errors in ac measureme
32. e divider R1 and R2 is used to set the gain of the associ ated amplifier chain that is the ratio to 3 The net gain of the bridge amplifier loop is then 1 and the circuit oscillates at the frequency fo The resistance of thermistor R1 adjusts to the value needed to maintain constant amplitude oscillation The time constant of the thermistor is short enough to provide a rapid correction for amplitude variations but long enough to cause little distortion at the lower frequencies The thermistor operates at a high temperature in an evacuated bulb to minimize the effects of ambient temperature 5 3 THE OSCILLATOR AMPLIFIER The first stage of the oscillator amplifier shown in simplified form in Figure 5 2 consists of a field effect transistor Q101 connected as a source follower the drain of which is coupled to the emitter of the following trans istor Q102 This effectively degenerates any gate to drain impedance there by raising the input impedance Q101 is followed by PNP transistor Q102 which serves in combination with 0101 as a differential amplifier for Ejp the difference between positive feedback voltage and negative feedback voltage Ep The next two stages are NPN transistors 0103 in common emitter con figuration and Q104 operating as an emitter follower The oscillator has over 60 dB of negative feedback which produces three results low distortion very high input impedance and very low output im
33. e oscillators can be synchronized if their EXT SYNC jacks are connected together Oscillators connected in this manner will oper ate at the same frequency or multiples of the same frequency and can be made to differ in phase 75 by adjustment of the FREQUENCY dials within the lock range 4 3 WAVEFORM SYNTHESIZER The ability to lock onto harmonics lends the oscillator to interesting applications such as the Fourier synthesis of waveforms In the following example a square wave is synthesized by locking the oscillators on the sucessive odd harmonics present in the original square wave Any waveform can be synthesized in this manner provided a source of the necessary harmonics is available and the Fourier coefficients are known All syne inputs are paralleled and connected to the oscilloscope s square wave calibrator output as shown in Figure 4 1 The resulting wave form is shown in Figure 4 2 20 APPLICATIONS TYPE I560 P95 TELEPHONE PLUG TO DOUBLE PLUG PATCH CORD 5 SS TYPE 1309 OSCILLATORS Figure 4 1 Set up for generating the Fourier synthesis of a square wave Figure 4 2a Original l kHz square wave from oscilloscope Figure 4 2b Fifth harmonic which like the output of all the oscillators is sinus 9139 Figure 4 2c Synthesized square wave The five outputs are adjusted for phase coherence and are summed in the ratio of their respective Fourier coefficients 4 4 ACCURATE FREQUENCY SOURCE WI
34. een minimum rise time and acceptable overshoot may be made for a particular load by the adjustment of C302 Figure 3 13 the internal overshoot control The rise time of the square waves corresponds to the response time of an amplifier with a bandwidth greater than 10 MHz This is well beyond the 13 Q TYPE 1309 OSCILLATOR 50 ns cm b 200 5 Figure 3 12 Leading edge of 10 kHz Figure 3 12b Leading edge of same square wave into 50 load signal at open circuited end of cable 0302 Figure 3 13 Overshoot control in the square wave generating circuit For instructions on access to components refer to 3 paragraph 6 3 bandwidth normally encountered in audio equipment but the fast internal transition can nevertheless be used to advantage for lower frequency testing The rise time can be externally lengthened by using the time constant 2 2 RC of the 600 ohm output impedance and the capacitance 30pF foot of the shielded cable used to connect the oscillator to the device under test This produces a monotonically increasing leading edge with no overshoot or ripple and yet fast enough to check bandwidth up to 1 MHz See Figure 3 12b for an example of this waveform A wide bandwidth indicator system must be used to reproduce faithfully the transitions of the square waves For a system with 7 individual compo nents of specified rise time the equation for over all rise time is 5 2 2 DUNS FEDT 2 Te Ty t
35. equency counter such as the General Radio Type 1150 Digital Frequency Meter is rec ommended The interconnections for operating the Type 1309 with the Type 1150 are shown in Figure 3 1 3 2 2 VOLTAGE To set accurately the output voltage between the calibrated steps of the OUTPUT attenuator use of a voltmeter such as the General Radio Type 1806 Electronic Voltmeter is recommended The interconnections for oper ating the Type 1309 with the Type 1806 are shown in Figure 3 1 1309 OSCILLATOR 1806 1560 95 TELEPHONE ELECTRONIC PLUG TO DOUBLE PLUG PATCH CORD VOLTMETER 1309 OSCILLATOR TYPE 150 DIGITAL FREQUENCY gt METER TO EQUIPMENT UBLE PLUG PATCH CORDS UNDER PEST Figure 3 1 Interconnections for operating the Type 1309 with auxiliary instruments 3 3 OUTPUT CONNECTION The full oscillator output is available through the front panel OUTPUT terminals The lower terminal although insulated from the panel at the bind ing post is internally connected to the circuit ground of the oscillator which is in turn connected to the chassis The chassis is normally connected to the power line ground through the 3 wire power cord Hum and extraneous signal pickup due to ground loops may occur when the oscillator is used with other ac line operated equipment These signals can be of considerable magnitude compared to the low levels available from the oscillator s atte
36. er foot which at 100 kHz amounts to a shunt impedance of about 55 For example the open circuited output voltage at the end of five foot shielded lead is less than one volt at 100 kHz Therefore cable length should be kept to a minimum when a high impedance load is to be driven at high fre quencies Figure 3 14 Diagram of the EXT SYNC output equivalent circuit 3 6 3 INPUT SYNCHRONIZING CHARACTERISTIC The oscillator frequency may U as be synchronized or locked with any 68 2 input signal which is applied to the Ela EXT SYNC jack if the oscillator is tuned to the approximate frequen eg j cy of the input The range of fre Nie gt 21 9 quencies over which this synchro 2 9ja nization will take place is a func tion of the amplitude of the frequen cy component to which the oscil lator locks It increases approxi VOLTS rms INPUT AT SYNCHRONIZING FREQUENCY mately linearly and produces a lock range of about 13 for each volt input see Figure 3 15 Figure 3 15 Locking range versus input voltage 15 TYPE 1309 OSCILLATOR The oscillator maintains synchronization within the lock range if either the oscillator dial frequency or the syncbronizing frequency is changed How ever there is a time constant of about one second associated with the sync ronization mechanism Thus if the amplitude or frequency of the sync signal or the dial
37. es fully cw 1 kHz mechanical adjustment Connect the counter and voltmeter to the EXT SYNC jack and set the FREQUENCY dial for a frequency count of exactly 1 000 kHz Loosen the set screws on the FREQUENCY dial and position the dial on the shaft to read exactly 1 with a reading of 1 000 kHz on the counter Snug up the set screws but don t tighten Note the voltmeter reading 10 kHz capacitor adjustments Set the FREQUENCY dial to exactly 10 Simultaneously adjust C402 and C403 for a counter frequency reading of ex actly 10 kHz and the same voltmeter reading noted above The mechanical adjustment and capacitor adjustments interact repeat until the measurements are correct and the voltmeter readings are equal at both ends of the dial 37 TYPE 1309 OSCILLATOR Stability Disconnect the voltmeter and connect an oscilloscope in its place Rotate the FREQUENCY dial over the entire 1 kHz 10 kHz range there must be no instability or other erratic operation If there is it is usually caused by the rotor wiper arm of the tuning capacitor C401 or dust in C401 Dis connect the oscilloscope Remove all connections to the EXT SYNC jack 100 kHz adjustment Set the FREQUENCY range to 10 kHz 100 kHz and set the FREQUENCY dial to 10 Adjust C105 for a counter frequency reading of exactly 100 kHz Frequency checks Perform the following frequency checks TABLE 6 5 FREQUENCY CHECK Range Dial Setting Setting Counter Reading Remark
38. esistance of signal wire shield 3 4 CHARACTERISTICS 3 4 1 FREQUENCY RESPONSE The output is 5 volts open circuit behind 600 ohms and is adjustable over a 60 dB range by a step attenuator 20 dB per step and a 20 dB bridged T constant impedance attenuator The output is constant within 2 from 10 Hz to100 kHz for loads of 600 ohms or higher Typically within the audio range changes are imperceptible on the usual analog type of voltmeter The output voltage as a function of frequency of a typical oscillator is shown in Figure 3 6 10 OPERATING PROCEDURE a E 3 o ul gt lt aa u 2 10 142 20 50 100 200 500 IkHz 2 5 10 20 50 100 FREQUENCY Figure 3 6 Typical oscillator output voltage versus frequency 3 4 2 FREQUENCY STABILITY High stability frequency determining components in the oscillator and low internal power dissipation result in a stable output frequency Drift during warm up is typically below 0 1 Typical long term stability after warmup at 1 kHz is shown in Figure 3 7 This graph was plotted under normal laboratory conditions during the winter months heat on during the day and off at night Bees a SM mots gem ma sme i miis md LU a E SUBE ES PODER REGE HOURS Figure 3 7 Typical long term drift 3 4 3 NOISE Hum is less than 504V 0 001 of full output regardless of the attenu ator setting Noise at frequencies distant fr
39. f R105 C103 108 102 collector 103 emitter Q103 collector 0104 emitter Junction of R115 C110 AT111 Voltages are approximate Actual voltages may vary 2 to 1 in individual instruments SERVICE AND MAINTENANCE 6 7 CALIBRATION PROCEDURE 6 7 1 INTRODUCTION This procedure can be used for troubleshooting or calibration If used for trouble shooting the steps can be performed in any order The usual practice would be to perform only the step that pertains to the sus pected circuit If used for calibration the steps should be performed in sequence since one step serves as a foundation for the next A complete calibration insures that all circuits are operating properly and within specifications The Type 1309 Oscillator incorporates the high reliability one would expect of servatively designed semiconductor circuits and routine calibrations are unnecessary 6 7 2 EQUIPMENT The following equipment is required for a complete calibration of the Type 1309 Oscillator The specifications given for the equipment are those necessary for the calibration of the Type 1309 and are not necessarily those of the recommended equipment Metered adjustable autotransformer Output 105 to 125 V or 195 to 235 or 210 to 250 V 12 W Meter Ac 3 accuracy The Type WSMT3W Metered Variac Autotransformer is recommended Electronic voltmeter Voltage 0 50 V dc 5mV 5 V rms 10 Hz 100 kHz 2 accuracy
40. ffective bandwidth is also the same function of the amplitude For ex ample if a 1 volt signal is used to synchronize the oscillator at 100 kHz and provides a 3 lock range the oscillator will have a 3 dB bandwidth of 3 kHz 3 of 100 kHz to perturbations in frequency Thus frequency deviations in the 100 kHz source at a 3 kHz rate will be reduced 3 dB in the oscillator out put Figure 4 6 shows one example of jitter reduction Note the cycle to cycle change in frequency has been greatly reduced yet the relatively long term change of about 1 has been faithfully tracked The low frequency used in this example was chosen for convenience in making the graphic recordings A reduction in jitter or fm can be made at any frequency within the range of the oscillator 10Hz to 100kHz The ability to track drift however is still limited by the one second time constant of the thermistor GENERAL RADIO COMPANY WEST CONCORD MASE 55 TIME Figure 4 6 One example of jitter reduction a Output frequency of a drifting jittery 10 Hz source b Output of the Type 1309 synchronized to the 10 Hz source 4 5 2 INCIDENTAL A M REDUCTION Just as the oscillator can be used to reduce jitter or fm in a signal it can also be used to reduce a m This is a natural consequence of the oscil lator s similarity to a high Q filter The amplitude modulation on any signal to which a Type 1309 is synchronized is reduced to the extent that the mo
41. fy and measure in this case since they are not masked by the oscillator output If the Type 1309 is rack mounted the chassis will be connected to the rack frame ground and a ground loop can not be avoided by operating the in strument with a two wire power connection Again this loop may cause an appreciable amount of hum at low levels if there are 60 Hz ground currents through the rack panels Figure 3 4 The effect of the ground currents may be reduced by isolation of the oscillator circuit ground from its chassis Figure 3 5 As much as 10 ohms may be inserted to provide this isolation A one half watt resistor may be added by replacing the wire lead between AT101 and the front panel ground connection see Figures 6 3 and 6 5 or by substituting the connecting wire link leading to AT101 on top of the printed circuit board Paragraph 6 3 plains how to obtain access to the top of the board TYPE 1309 OSCILLATOR TYPE 1309 OSCILLATOR DEVICE UNDER TEST GROUND CURRENT 1309 14 3 WIRE AC POWER LINE Figure 3 4 Ground loop formed when Type 1309 is rack mounted with another device not necessarily ac line operated 60 Hz voltage due to panel ground currents and resistance TYPE 1309 OSCILLATOR DEVICE UNDER TEST 60 Hz GROUND CURRENT 3 WIRE AC POWER LINE 19815 Figure 3 5 60 Hz voltage due to panel ground current reduced because most of voltage appears across resistance R rather than r
42. itter of Q301 to rise The rising emitter voltage causes Q301 to conduct all the harder The result is a regenerative process which leaves Q301 conducting heavily and Q302 conducting not at all When the input signal goes a bit more positive than the voltage on Q301 s emitter a similar regenerative process occurs which leaves Q301 off and Q302 on The action of the Schmitt circuit is illustrated in Figure 5 3 Trimmer C302 is a speed up capacitor which determines how rapidly Q302 switches on and off and thereby the shape of the output waveform which appears at the collector of Q302 For maximum switching speed Q301 is prevented from saturating by the network including CR301 and CR302 Diode CR303 prevents the base emitter voltage of Q301 from becoming excessive during the positive swing of 29 1309 OSCILLATOR aso CL E 9301 ON La INPUT SIGNAL 0301 COLLECTOR VOLTAGE t Q302 COLLECTOR VOLTAGE SQUARE WAVE OUTPUT 1309 22 Figure 5 3 The switching action of the Schmitt circuit the input signal The exact point on the input waveform at which the switch ing of Q301 takes place is set by R303 the SYMMETRY control which ad justs the bias at the base of Q301 5 5 THE POWER SUPPLY The power supply see Figure 6 5 consists of a full wave rectifier CR501 and CR502 followed by a pi section filter R501 and C501 A and B and a constant voltage regulator Q
43. nt to General Radio for service please write to our Service Department or nearest Sales Engineering Office request ing a Returned Material Tag Use of this tag will ensure proper handling and identification For instruments not covered by the warranty a purchase order should be forwarded to avoid unnecessary delay 6 3 ACCESS TO COMPONENTS To remove the cover of the Type 1309 A turn the two knurled nuts on the rear of the cover counterclockwise and pull the cover straight back and off To obtain access to the components on the etched board disconnect from the etched board the six wires that are connected to the FREQUENCY range switch remove the two securing screws and swing the board up See Figure 6 1 31 1309 OSCILLATOR Figure 6 1 Access to the etched board components 6 4 MINIMUM PERFORMANCE SPECIFICATIONS The check of specifications outlined in Table 6 1 is recommended for incoming inspection or periodic operational testing Detailed procedures are given in the Calibration Procedure paragraph 6 7 Conditions 115 V line 30 minute warmup OUTPUT LEVEL FREQUENCY 2 Range Dial f a Output level 100Hz 1kHz 5 25 V rms open circuit Frequency each 2 of indicated value Distortion 100Hz 1kHz 0 05 1kHz 10kHz lt 0 05 Hum 100112 11112 Syne output 100Hz 1kHz Output power 100Hz 1kHz gt 2 45 V into 6000 10 mW Output response 100Hz 1kHz 10Hz 100Hz 0 98 1 02 V 10kHz 100kHz 0
44. nted below b Remove the screws that se cure the front panel to the aluminum end frames c Remove the spacers between the front panel and the end frames If two instruments are to be mounted side by side join them as follows d On one instrument install clips with the front panel screws removed earlier and install the nut plates with the foot screws removed earlier e Secure the two instruments together with front panel screws through the remaining hole in each clip and with a foot screw through the remain ing hole in the nut plate Note that the instruments can be bench mounted side by side this manner Simply do not remove the two feet from each outside end frame and do not install the adaptor plates f Install two clips on each a daptor plate with the wing screws lockwashers and nuts supplied g Attach the adaptor plates to the instrument with the front panel screws removed earlier h Mount the assembly in the rack with the 10 32 screws supplied FRONT PANEL SCREW SPACER RUBB R FOOT 8 END FRAME ADAPTOR PLATE WING SCREw NUT LOCKWASHER e FRONT PANEL SCREW 10 32 SCREW ASHER Figure 2 1 Rack mounting the Type 1309 Oscillator TYPE 1309 OSCILLATOR 2 3 POWER CONNECTION Connect the Type 1309 to a source of ac power as follows a Switch the LINE switch on the back panel to the voltage of the power line 100 125 V or 200 250 V b Connect
45. nts Figure 4 8 shows one example of amplitude modulation Figure 4 8 10 kHz output of an oscillator modulated at 500 Hz by a 9 5 kHz signal applied to the EXT SYNC jack 25 1309 OSCILLATOR 4 7 OUTPUT SYNC 4 7 1 OSCILLOSCOPE TRIGGER Figure 4 9 Since the sync output is independent of the output level it can be used to trigger an oscilloscope in applications where the oscillator output is often varied thereby eliminating frequent readjustment of the oscilloscope trigger trigger Circuits VERTICAL EXT OUTPUT INPUT SYNC TYPE 1309 DEVICE UNDER OSCILLOSCOPE 5 4 Figure 4 9 EXT SYNC signal used to trigger an oscilloscope 4 7 2 COUNTER TRIGGER Figure 4 10 A counter can be driven from the EXT SYNC jack when more precise adjustment of frequency is desired or when the front panel output is not suf ficient to trigger the counter OUTPUT TYPE 1309 COUNTER Figure 4 10 EXT SYNC signal triggers frequency counter 26 PRINCIPLES OF OPERATION SECTION 5 PRINCIPLES OF OPERATION 5 1 GENERAL As shown in Figure 5 1 the Type 1309 Oscillator is a capacitively tuned Wien bridge oscillator with range changing accomplished in four decade steps by the changing of and Rp A large amount of negative feedback is used and is responsible for the very low distortion of the sine wave output The 5 volt output of the Wien bridge oscillator is switched either to be attenuated by a 6
46. nuator Figure 3 2 shows a ground loop that is formed when the 1309 is bench mounted with another line operated device and both use 3 wire power line connections If there is 60 Hz ground current flowing through both sides of the loop it can cause a voltage drop in the signal lead ground which appears in the input of the device under test TYPE 1309 OSCILLATOR DEVICE UNDER TEST GROUND CURRENT POWER LINE Figure 3 2 A Ground loop 60 Hz voltage due to ground current and signal wire shield resistance OPERATING PROCEDURE When the Type 1309 is used as a bench instrument the current can usu ally be sufficiently reduced by operating one of the devices on a two wire power cord see Figure 3 3 which opens the loop TYPE 1309 OSCILLATOR DEVICE UNDER TEST 60 Hz GROUND CURRENT 3 WIRE AC ms POWER LINE Figure 3 3 Operating the Type 1309 A with a two wire power cord to eliminate the ground loop of Figure 3 2 No 60 Hz voltage since ground current does not flow through signal wire shield The OV position on the OUTPUT switch of the Type 1309 can be very useful in trying to reduce the effects of ground loops Only the extrane ous noise and hum appear at the device input when the oscillator is used in this position The oscillator signal is removed yet all of the wiring shield ing and impedance levels connecting the two devices remain the same The extraneous signals present are much easier to identi
47. om a l kHz fundamental meas ured in a bandwidth of 5 Hz to 500 kHz is typically 0 005 Noise close to the fundamental is also low as the spectrum analysis of a 1 kHz output shows Figure 3 8 Note the absence of components at the line frequency or its multiples Refer to paragraph 3 3 for a discussion of how to minimize pickup of noise from external sources 11 1309 OSCILLATOR ANALYZER BANDWIDTH 120 Hz 60Hz Z 60 Hz 4 120112 IE z I EEEE 80 EEEEEEEEEFEEEEI 100 Figure 3 8 Spectrum analysis of the oscillator output at 1 kHz 3 4 4 DISTORTION Total harmonic distortion THD is less than 0 05 from 200 Hz to 10 kHz and less than 0 25 at 10 Hz and 100 kHz with a 600 load or open circuited Figure 3 9 When the attenuator is set for open circuit voltages of one volt or less the load seen by the oscillator is between 600 ohms and an open circuit regardless of the size of the external load 20 50 100 200 500 I kHz 2 5 10 20 50 100 FREQUENCY 309 5 Figure 3 9 Typical harmonic distortion vs frequency of Type 1309 sine wave output 3 5 SQUARE WAVE OUTPUT 3 5 1 OUTPUT CHARACTERISTICS The square wave output of the Type 1309 is positive going from 0 volts V to greater than 5 volts It is dc coupled so that there is no ramp off This makes the oscillator a convenient signal source for measuring the ramp off of
48. pedance Both the signal output and the positive feedback for the Wien bridge are taken from the emitter of Q104 The sine wave output signal is transmit ted through a 600 coupling capacitor to switch S201 which forms a 60 dB step attenuator in the first four positions and connects in the fully clockwise position the square wave generating circuit to the oscillator output The output from the step attenuator is applied to the output jack via a 20 dB con stant impedance bridged T attenuator R205 through R208 28 PRINCIPLES OF OPERATION WIEN BRIDGE AMPLIFIER AC FEEDBACK Ca 520 R Eour 1309 21 Vcc Figure 5 2 Simplified schematic diagram of the Wein bridge oscillator circuit used in the Type 1309 A The dc operating conditions are maintained by the negative dc feedback divider R108 and R109 The proper bias level is set with R102 The com plete circuit of the oscillator appears in Figure 6 5 5 4 THE SQUARE WAVE GENERATING CIRCUIT The square wave generator see Figure 6 5 is a modified Schmitt cir cuit consisting of two emitter coupled PNP transistors Q301 and Q302 The circuit works in the following way An input signal slightly more negative than the emitter voltage of Q301 applied to the base of Q301 causes it to turn on conduct This forms a positive going signal at the collector of Q301 and the base of Q302 This positive signal causes Q302 to conduct less which causes the voltage at the em
49. rom 0 to 50 C and to be stored in locations with ambient tempera tures from 40 to 70 C As with all low frequency variable capacitance RC oscillators the oscillator circuit in the Type 1309 operates at impedance levels of over 1000 megohms Consequently circuit operation especially frequency accuracy on the lower ranges may be affected under conditions of very high humidity These effects may be minimized by allowing the instrument a warmup period long enough to allow internally generated heat to reduce the humidity within the instrument 2 2 RACK MOUNTING 2 2 1 RELAY RACK ADAPTOR SETS The Type 1309 Oscillator can be rack mounted alone or with another 8 by 54 inch convertible bench instrument by means of the appropriate adap tor set listed below The adaptor panels are finished in charcoal gray crackle paint to match the front panel of the instrument and come complete with the necessary hardware to mount to the instruments and to the rack For instruc tions on grounding the rack mounted Type 1309 refer to paragraph 3 3 TABLE 2 1 RELAY RACK ADAPTOR SETS Type Description Catalog Number Relay Rack Adaptor Set used to rackmount the Type 1309 alone 0480 9638 Relay Rack Adaptor Set used to J rackmount the Type 1309 with a 0480 9636 Type 1232 1311 or 1396 INSTALLATION 2 2 2 ATTACHMENT OF ADAPTOR SETS Figure 2 1 a Remove the rubber feet if necessary to clear an instru ment mou
50. s kHz lOkHz 1 1kHz Frequency 980 to 1020Hz Mechanically position 1kHz 10kHz 1 5 1 5kHz Frequency 1470 to 1530Hz FREQUENCY dial 1kHz 10kHz 2 5 2 5kHz Frequency 2450 to 2550Hz 1kHz 10kHz 5 5kHz Frequency 4900 5 100Hz 1 2 10 2 10 10kHz Frequency 9800 10 200Hz Adjust C402 and C403 100Hz 1kHz 5 500Hz Ten period 19 6 to 20 4 ms 10kHz 100kHz 5 50kHz Frequency 49 to 51kHz 1OkHz 100kHz 10 100 Frequency 98 0 to 102kHz Adjust C105 10Hz 100Hz 10 100Hz Ten period 98 to 102 ms 10Hz 100Hz 1 10Hz Ten period 980 to 1020 ms Adjusted earlier in this step 6 7 6 DISTORTION FREQUENCY range 100 Hz 1 kHz FREQUENCY dial 2 200Hz OUTPUT switchz sw OUTPUT control v ws fully cw 200 Hz Disconnect the counter from the OUTPUT terminals and connect the e wave analyzer and the 600 load resistor in its place Measure the second 38 SERVICE AND MAINTENANCE and third harmonic distortion 400 Hz and 600 Hz total distortion must be less than 0 05 Total distortions second harmonic distortion third harmonic distortion 10 kHz Change the FREQUENCY range to 10 kHz 100 kHz 10 kHz and measure the second and third harmonic distortion 20 kHz and 30 kHz total distortion must be less than 0 05 100 kHz Change the FREQUENCY dial setting to 10 100 kHz and measure the second and third harmonic distortion 200 kHz and 300 kHz total distor tion must be less
51. the lock range is a function of the amplitude see Fig ure 3 16 Figure 3 16 Phase shift relative to input frequency and amplitude The input impedance of the EXT SYNC jack is 12 at all frequencies except the synchronizing frequency At the synchronizing frequency the im pedance in general is complex and can vary over a wide range including negative values because the jack is also a source at the synchronizing fre quency Since the jack is a simultaneous source and input care should be taken to insure the sync output voltage does not interfere with the external sync drive source The high output impedance of the EXT SYNC jack makes it easy to minimize the sync output signal For example if the jack is fed from a 600 ohm source less than 70 mV will appear across the source 16 OPERATING PROCEDURE 3 6 4 INPUT FREQUENCY SELECTIVITY The RC network in the oscillator used to determine the frequency of oscillation and to reduce hum noise and distortion can also be used to filter signals applied externally Signals applied to the EXT SYNC jack which are close to the frequency of synchronization will be amplified in the output but those frequencies distant from the frequency of synchronization will be re duced The intrinsic selectivity or Q of this filter is constant and determined only by the RC Wien network The voltage gain between the EXT SYNC jack and the OUTPUT ter minals is constant at any frequency except the freq
52. the oscillator to be mounted in a standard 19 inch relay rack Type 480 P316 Relay Rack Adaptor Set This adaptor set allows the oscillator to be f mounted side by side with another 8 x 5 inch convertible bench instrument in a standard 19 inch relay rack Type 1396 Tone Burst Generator This instrument allows the output of the oscil lator to be gated on and off coherently The gate on and gate off times are independently adjustable from 2 to 128 cycles of any output frequency of the oscillator up to 100 kHz With the Type 480 P316 Relay Rack Adaptor Set listed above the Type 1396 and Type 1309 A can be bolted together to form a single unit for either bench or rack installation Type 1232 Tuned Amplifier and Null Detector This instrument with the oscillator forms a detector oscillator assembly with a sensitivity of 0 1 and a frequency range of 20 Hz to 20 kHz plus two fixed frequencies of 50 and 100 kHz With the Type 480 P316 Relay Rack Adaptor Set listed above the Type 1232 and oscillator can be bolted together to form a single unit for either bench or rack installation 47
53. uency of oscillation re gardless of the amplitude of the incoming signals The curve of Figure 3 17 may be used directly to determine the amplitude of any frequency component in the oscillator output if the amplitude of the input is known 8 VOLTAGE GAIN BETWEEN EXT SYNC JACK AND UNATTENDED OUTPUT 01 02 05 07 10 20 50 70 100 FREQUENCY NORMALIZED INPUT FREQUENCY DIAL FREQUENCY Figure 3 17 Voltage gain from EXT SYNC jack to OUTPUT as a function of distance from center frequency 17 TYPE 1309 OSCILLATOR For example we wish to determine the possible reduction the harmo nic content of a l volt l kHz signal which has approximately 1 0 0 01V second harmonic distortion by filtering with the Type 1309 The signal is applied to the EXT SYNC jack and the OUTPUT control is set for a five volt sine wave output signal From the graph the gain at the second harmonic is approximately 2 2 disturtion ia gog cp de total amplitude 5 0 If the amplitude of the external signal is reduced to 0 5V 0 005 V har monic content the distortion at the output of the Type 1309 becomes 002229 100 0 22 since the total output voltage and the gain at the second harmonic remain the same In general it is not possible to reduce the distortion below the level normally present in the oscillator and little would be gained in the preceding example by reducing the input to less than 0 05
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