general radio gr-650 operation and maintenance manuial

8/12/2019 General Radio GR-650 Operation and Maintenance Manuial

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OPERATING AND M INTEN NCEINSTRUCTIONS

TYPE 650 AIMPEDANCE BRIDGE

ndTYPE 650 P1

OSCILLATOR AMPLIFIERForm 346 1May 1957

GENER L R DIO COMP NY75 MASSACHUSETTS AVENUE

CAMBRIDGE 39 MASSACHUSETTSSALES ENGINEERING OFFICES

NEW YORK: Broad Avenue at LindenRidgefield New Jersey

WASHINGTON: 8055 13th StreetSilver Spring Maryland

CHICAGO: 920 South Michigan AvenueChicago 5 Illinois

LOS ANGELES: 1000 North Seward StreetLos Angeles 38 CaliforniaPHILADELPHIA: 1150 York Road

Abington PennsylvaniaSAN FRANCISCO: 1182 Los Altos Avenue

Los Altos California

WEST COASTWestern Instrument Company826 North Victory Boulevard

Burbank California

REPAIR SERVICESEAST COAST

General Radio CompanyService Department

275 Massachusetts AvenueCambridge 39 Massachusetts

CANADABayly Engineering Ltd.

Fi rst StreetAjax Ontario

Pr inted in U.S.A.


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TABLE OF CONTENTS

Section 1.0 Introduction1.1 General

Section 2.0 Installation2.1 Accessories Supplied2.2 Accessories Required.2.3 Power Supply

Section 3.0 Measurements in the Direct Reading Range3.1 Direct Current Resistance Measurements.3.2 Alternating Current Resistance Measurements3.3 Capacitance Measurements3.4 Inductance Measurements3.5 Summary .

Section 4.0 Other Measurements .4.1 Accessories.4.2 Voltage Limits4.3 Ground Capacitance Errors.4.4 Extension of Range.4.5 Spedal Applications

Section 5.0 Electrical Circuits.5.1 General5.2 Resistance Measurements5.3 Capacitance Measurements .5.4 Inductance Measurements5.5 References

Section 6.0 Type 6OO P1 Osclllator Amplifier6.1 General6.2 Directions for Installation .6.3 Operating Instructions

Page

2222223345556889

11011111111111112

Service and Maintenance Notes for the Type 650 A Impedance Bridge 13Service and Maintenance Notes for the Type 6oo P1 Oscillator AmJiifier 16Vacuum. Tube Data . 19Wiring Diagram for the Type 650 P1 . 21Wiring Diagram for the Type 650 A 25


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View of theType 650 Pl Oscillator AmplifierInstalled in the BatteryCompartment of the

Type 650 A Impedance Bridge

Panel View of Type 650 AImpedance Bridge


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TYPE 650-A IMPEDANCE BRIDGE

3.2 ALTERNATING-CURRENT RESISTANCEMEASUREMENTS3.21 Procedure: To make l-kc alternating-currentresistance measurements, proceed in the followingmanner:1) Set DETECTOR switch on EXT.2) Connect unknown resistance to R termina.1s.3) Set D-Q multiplier switch on R.4) Set GENERA TOR switch on 1 KC. * A faint l-kchum should be heard coming from the microphone hummer under the panel.5) Connect a }:Bir o head teleJilones to the EXTERNAL DETECTOR terminals. A loud l :kc tone will beheard in the telephones.6) With the CRL dial set in the vicinity of 1.0turn the CRL switch in such a direction as to decreasethe intensity of this tone, choosing that position whichyields the least sound. Adjust the setting of the CRLdial until silence or minimum sound is obtained. f a

balance cannot be obtained, change the setting of theCRL switch until a satisfactory balance is reached.7) The resistance of the unknown resistor is thereading of the CRL dial multiplied by the factor indicatedby the CRL switch 'on the circular row R.

3.22 Accuracy: The same accuracy statements thatwere given for direct-current measurement hold forthis measurement except that the error for the I-ohmsetting of the CRL switch is 5%, increasing to 10% forthe O.I-ohm setting, when the internal generator is used.A good null mlance can be obtained only when theunknown resistance has a small reactance comparableto that of the various resistors which make Ul- the remainder o the r i ~ e circuit, because for this connection

the r i ~ e has only one control. The criterion of a goodnull balance is that as the CRL dial is moved o mIancethe passage of the sliding contact over the individualwires can be detected. In general, this condition limitsthis type of measurement to standard r ~ s i s t o r s andresistance boxes.When the unknown resistor has considerablereactance, a balance can be obtained by connecting acapacitor across one of the bridge arms, as explainedin SECTION 4.51, A-C Resistance with Reactance.

3.3 CAPACITANCE MEASUREMENTS3.31 Procedure: To make alternating-current capa

citance measurements at 1 kc, proceed as follows:1) Connect the unknown capacitor to the CL terminals at the right with its shield if any) connected tothe LOW terminal.2) Set the DQ switch on C -DQ and the DQ dial,which is then connected to the bridge,at O.(3) Set the DETECTOR switch at EXT. and theGENERATOR switch at 1 KC.* A faint l-kc hum shouldbe heard coming from the microphone mounted belowthe panel. A loud l-kc note will be heard in the telephones.4) Ground the bridge at any terminal marked G.(5) With the CRL dial set in the vicinity of 1.0,turn the CRL switch in such a direction as to decrease3

the intensity of this note, choosing that poSition whichyields the least sound.6) Turn theCRL dial until mInImum soond is obtained.7) Increase the setting of the DQ dial to obtain abetter minimum.8) Alternately adjust the CRL and DQ dials untilthe setting of each is unchanged on further adjustmentof the other. When the final balance is obtained, i t ispossible to detect the passage of the sliding contactover the individual wires i f either dial is moved offbalance. This condition should always be attained forthe CRL dial. t will be found that when the setting ofthe DQ dial is greater than 2 (a condition which seldomoccurs), the successive settings of the CRL and DQdials progress across the dials. This is because thetwo balances of the bridge are not independent. Thenumber of successive settings which must be madebefore a good null balance is reached can be reduced bytaking advantage of the orderly progression of the settings and slightly over-setting each one in the directionit will move the next time. When the true balance pointis passed on one dial, the progression of the other dialin its next setting will be reversed.9) The series capacitance of the unknown capacitoris then given by the reading of the CRL dial multipliedby the factor indicated by the CRL switch on the circularrow C.** The parallel capacitance of the capacitor canbe calculated from the formula

C - Cs (1)p - 1 + D2(10) The dissipation factor D of the unknown capacitoris the reading o the DQ dial multiplied by the factorindicated by the DQ switch on the circular row marked

MULTIPLIER. f the setting of the DQ dial is less thanone, greater ~ c u r c y can be attained by resetting theDQ switch to C-D ~ d rebalancing the bridge by meansof the D dial.Dissipation factor is the ratio of series resistanceto series reactance.

2)t may have any value from zero to infinity.11) The series alternating-current resistance of

the capacitor can be calculated from the expressionR ~w 3)

The frequeJry c the microJilone hummer is 1.00 :to.O 5 kc.The parallel resistance of the ca}:Bcitor can be calculatedfrom the formulaeRp = 1 + D2 Rs = 1 + D2 =_ _ 4)D2 Dw Dw

where: Rs = series resistanceCs = series capacitanceC p = parallel capacitance*When the Type 650-Pl is used, see footnote on page 2and SECTION 6.**See also second paragraph of SECTION 4.57.


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GENERAL RADIO COMPANY

EXAMPLES:CRLDial CRLSwitch Ca}Xlcitance DQ D D2.672.672.672.67

100110010

.267 mj.Lf2.67 mj.Lf

.000267 j.Lf

.00267 j.LfDial Dial Switch Dissi}Xltion Factor

267 mj.Lf .267 j.Lf26.7 j.Lf3.32 Accuracy: The accuracy of the capacitancereadings is 1 between 1000 IJ.lJ.f and 10 j.Lf increasing

to 2 at 100 j.Lf, when the CRL dial is set on its maindecade between 1.0 -and 10. The small decades below1.0 are provided for convenience in obtaining an initialbalance and to allow the measurement of small ca}Xlcitances. Their accuracy is determined by the spacingof their graduations. The zero ca}Xlcitance of the bridgecan be measured by leaving the CL terminals open. tis about 10 IJ.j.Lf. The capacitance of the lead wires usedin connecting the unknown capacitor to the bridge canbe measured by disconnecting the lead running from theleft CL terminal to the unshielded terminal of the capacitor at the ca}Xlcitor, being careful not to alter therelative position of the leads. By using such zero corrections, capacitances up to 200 IJ.lJ.f can be measuredto 2 IJ.lJ.f and above 200 j.LlJ.f to 1 .

The accuracy of the dissipation factor readingsis 20 or 0.005, whichever is the larger for capacitances greater than 500 1J.1J.f. For capacitances lessthan 500 1J.j.Lf, when measured on the 100 j.LlJ.f multiplier,the error increases as capacitance decreases, reaching100 for 100 j.LlJ.f. The largest source of error is thecapacitances acroos the ratio arms, whose effects changewith settings of the CRL switch. For values of dissipation factor greater than 0.05, the error is not greaterthan 10 . Another source of error is the zero capacitance Co and its dissipation factor DO

The capacitance and dissipation factor D of the un-known capacitor are: C C C= 1 - 0D1C1 - ~ o (5)D = = = = ~ = = . . . . . : : . .C1 - Co

where subscript '1' refers to the bridge readings withthe unknown connected and subscript '0' to the readingswith the unknown disconnected.3.4 INDUCTANCE MEASUREMENTS

3.41 Procedure: To make alternating-current inductance measurements at 1 kc, proceed as follows:

(1) Connect the unknown inductor to the CL terminalsat the right with the shield (if any) connected to the LOWterminal.(2) Set the DQ switch at L-DQ and the DQ dial at 10.(3) Set the DETECTOO and GENERATOO* switchesat the same points as for capacitance measurements (seeabove) and ground the bridge at any terminal marked G.*When the Type 650-P1 is used, see footnote on page 2and SECTION 6.

4

(4) With the CRL dial set in the viCinity of 1.0, turnthe CRL switch in such a direction as to decrease theintensity of the tone heard in the telephones, choosingthat position which yields the least sound.(5) Turn theCRL dialuntil minimum sound is obtained.(6) Decrease the setting of the DQ dial to obtain abetter minimum. f it appears necessary to increasethe setting 'of the DQ dial above 10, reset the DQ switchto L-Q and rebalance the bridge by means of the Q dial.( 1) Alternately adjust the CRL and DQ or Q dialsunW the setting of each is unchanged on further adjustment of the other. When the final balance is obtained,it is possible to detect the }Xlssage of the sliding contactover the individual wires if either dial is moved offbalance. This condition should always be attained forthe CRL dial. t will be found that when the setting ofthe DQ dial is less than five, the successive settingsof the CRL and DQ dials progress across the dials asdiscussed in Caracitance Measurements, Section 3.31 (8).8) The inductance of the unknown inductor is thereading of the CRL dial multiplied by the factor indicatedby the CRL switch on the circular row L. This inductanceis series inductance when the DQ switch is set at L-DQ(Maxwell bridge) and parallel inductance when the DQswitch is set at L-Q (Hay bridge). The relation betweenseries and parallel inductance is given by the equation:

L = 1 + Q2 L (6)p Q2 s(9) The storage factor Q of the unknown inductor is

the reading of the DQ or Q dial multiplied by the factorindicated by the DQ switch on the circular row markedMULTIPLIER. storage factor is the ratio of series reactance to series resistance and also the ratio of parallelresistance to parallel reactance:

Q = s = wLs = Rp = Rp =. .. Rs Rs Xp c.;Lp D

(7)t may have any value from zero to infinity. t is thereCiprocal of the dissipation factor D.

(10) The series and rarallel altermting-current resistances of the indIctor can be calculated from the formulaeR - Qc.;LP - P

They are related by the expressionRp = (1 + Q2)Rs

8)

(9)where: Rs = series resistance Rp = rarallel resistanceLs = series inductance Lp= rarallel inductanceThe frequeocy of the microphone hummer is 1.00 O.05kc.


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EXAMPLES:CRL CRLDial Switch2.67 100 lh2.67 1 mh2.67 100 mh2.67 10 h

267 lh267 lh

Iilductance.267 mh2.67 mh267 mh

.000267 h.00267 h

.267 h26.7 h3.42 Accuracy: The accuracy of the inductance

readings is 2 between 100 lh and 1 h, increasing to 5at 10 hand 10 at 100 h, when the CRL dial is set onits main decade between 1.0 and 10. The small decadesbelow 1.0 are provided for convenience in obtaining aninitial balance and to allow the measurement of smallinductances. Their accuracy is determined by the spacingof their graduations. The zero inductance of the bridgecan be measured by short-circuiting the CL terminals.t is less than 2 lh and is generally negligible. Theinductance of the lead wires used in connecting the un

known inductor to the bridge can be measured by connecting the free ends together being careful not to alterthe relative position of the leads. By using this zerocorrection inductances up to 100 lh can be measuredto 2 lh and above 100 lh to 2 . The increasing errorappearing as the inductance increases is caused by theeffect of the capacitance to ground of the various parts

of the bridge. These have a considerable effect whenthe reactance being measured is large.

DQ Q D-QDial Dial Switch StorageFactor

2.641

The accuracy of the storage factor readings is20 up to a value of 40. For larger values the erroris best expressed as being 0.005 for its reciprocal dissipation factor D. The larger source of error is theshunt capacitances across the ratio arms whose effectschange with the settings of the CRL switch.

Errors may also be produced in both inductanceand s t o r ~ g factor by the linking of the stray magneticfield o the microphone hummer with the inductor beingmeasured. This inductor should be placed at least afoot away from the bridge.3.5 SUMMARY

Table i l l below iOOicates the settings of the controlsfor the types of measurement just discussed . .TABLE i l l

BATTE RY OPERATION 650 - P 1 OPERATIONType of Detector Generator Detector GeneratorMeasurement Switch Switch CRL-Switch D-Q Switch Switch SwitchD.C. Resistance 1. SHUNTED GALV. D.C. As necessary R 1. SHUNTED GALV . EXT. ON INT. OFF

2. GALV. for balance 2. GALV.l-kc Resistance EXT* 1 KC As necessary R EXT+ EXT. ON INT . OFFfor balanceInductance EXT* 1 KC As necessary L (Q or DQ EXT+ EXT. ON INT. OFFfor balanceCapacitance EXT* 1 KC As necessary C (D or DQ) EXT+ EXT. ON INT. OFFfor balance*Connect a pair of earphones to the EXTERNAL DETECTOR terminals and balance for minimum sound. +Connect a pair of earphones to the PHONESterminals and balance for minimum sound.

SECTION 4.0OTHER MEASUR.EMENTS

4.1 ACCESSORIES 4.11 Amplifier: The self-contained power supplyconsisting of four 1.5-volt dry cells for d-c measurements and a Type 572-B Microphone Hummer for l-kca-c measurements is sufficient for the attainment of

the accuracies mentioned in SECTION 1 except as notedin Part 3.13. For a -c measurements the telephones5

must be of good quality, equivalent in sensitivity andresistance to Brush Model A. For less sensitive telephones, for greater accuracy of setting, or for greaterease and convenience in obtaining a balance an amplifier is very useful. The General Radio Type 1231 Amplifier and Null Detector is suitable. The Type 650-P1Oscillator -Amplifier includes an amplifier for thispurpose.


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TABLE IVCRL SWitchRowR ArmB ArmA RatioB/A B 40C Rise for A BA + B E Max.

0.1f2 1 0 10 kf2 0.0001 0.000100 7 volts1- f2 10 0 10 kf2 0.001 0.000999 73 volts10 f2 100 f2 10 kf2 0.01100 f2 1 kf2 10 kf2 0.11 kf2 10 kf2 10 kf2 110 kf2 100 kf2 10 kf2 10100 kf2 100 kf2 1 kf2 100

4.12 Filters: The harmonics introduced by high-losscapacitors iron-


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J

6 VOLTS. . 1 ollt .

loo ooonlo ooonI ooon8 ~ n

In

R

CRL RHEOST T UNKNOWN0-11 200.n RESISTOR

Figure la. R

J

CRL RHEOSTATO I I 200n

* Series) LA = BNCp

BR = AN

100 000.0.10 000.0.I ooonl oonIOnIn

QA = Qp = Pu.:C p

R

Figure lc. L DQ) MAXWELL BRIDGE )

See Sec ti on 3.31 9) for relationship between ser ies andparallel capacitance; and Section 3.41 8) for inducta nc e .7

J

J

100 ooonl o ooonI ooonlOonI onInA

CRL RHEOST TO-II 200n

* Series)

Figure lb. C D or DQ)

EXT DEl.

100 ooon10 ooonI ooonl oonIonIn

CRL RHEOST T0- 11 2000

* Parallel) LA = BNCp1QA = Qp = PwCp

Figure Id. L Q) HAY BRIDGE)

R

R


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4.3 GROUND-CAPACITANCE ERRORS4.31 Internal Generator: Ground capacitances appearing across the various arms of the bridge introduceerrors in the reading of the D-Q dials when they areacross resistances, and in the reading of the CRL dial

when they are across the standard caplcitor. When usingthe internal generator these errors are negligible forthe CRL dial, but may amount to 10 or more for the D-Qdials, as stated in Sections 3.32 and 3.42 under Accuracy.The error in dissipation factor or storage factorcan be corrected by making the storage factors of thetwo ratio arms equal by adding cal-Qcitance across thatarm having the lower storage factor. Since, however, oneratio arm is continuously variable, equality of storagefactor may be obtained only for a particular setting.

The correct value of this added capacitance can be foundby measuring a standard reactor of known dissipationor storage factor.Since the junction of the CRL rheostat and thestandard capacitor is grounded, these ground ca pacitances are placed across this rheostat and the standardcapacitor. This causes the bridge to read low on capa

citance, inductance, and dissipation factor, and high onstorage factor.The fractional error in capacitance and inductanceis the ratio of the ground capacitance placed across thestandard capacitor to the capacitance of the standardcapaCitor. The error in dissipation factor and storagefactor is the product RwC, where C is the ground capacitance placed across, and R is the resistance of, theCRL rheostat. The error in dissipation and storage

factor caused by the presence of ground capacitanceacross the standard capacitor is usually negligible.4.32 External Generator: An external generatoralways has a considerable ground capacitance. The

division of capacitance between its terminals can bedetermined by the effect of the use of such an oscillatoron the measurement of a capacitor which has been previously measured with the internal power supply.

When one terminal of the oscillator is groundedto its panel, almost the entire ground capaCitance isassociated with the ungrounded terminal and will affectonly one arm of the bridge. Under these conditions,representative values of ground capacitance are 30 l lffor a battery-operated oscillator and 300 l lf for an a-coperated oscillator, the increase representing the interwinding capaCitance of the power-supply transformer.In general, the oscillator should be so connected tothe bridge that this capacitance is placed across thearm containing the standard capaCitor. The errorsintroduced in the reading of the CRL dial range from0.03 for a battery-operated oscillator and an inductance measurement to 3.0 for an a-c operated oscillator and a capacitance measurement.

See General Radio catalog for data.8

4.33 Shielded Transformer: The use of a shieldedtransformer between oscillator and r l ~ e will suppressthe effect of the ground capacitances of the oscillator,but will introduce similar effects on its own. TheType 578-A Shielded Transformer Is recommendedfor this use. Its terminal capacitances are equal andof about 35 l lf each, or the whole capacitance of 70 l l fcan be associated with either terminal. The errorswhich it will introduce will be comparable with thoseof a battery-operated oscillator. For 6O-cycle measurements the 2400-turn winding of this transformer can beconnected directly to the 115-volt supply. Head telephones cannot be used at 60 cycles because of their lackof sensitivi ty. A Type 1231 Amplifier and Null Detectoror a Type 1212-A Null Detector is recommended.

The Type 650-P1 Oscillator-Amplifier includes ashielded transformer.4.4 EXTENSION OF RANGE

4.41 Frequency: The reading of the CRL dial is in dependent of frequency but, since both dissipation factorand storage factor depend upon frequency, multiplyingfactors must be applied to the readings of the D-Q dials.DiSSipation factor at any frequency is the observed valueof D multiplied by the frequency expressed in kilocycles.storage factor at any frequency is the observed valueas obtained from the Q dial multiplied by, or the observed.value as obtained from the -Q dial divided by, thefrequency expressed in kilocycles.The accuracy of the resistance, capacitance,andinductance r e d i ~ s is independent of frequency from 60cycles to 10 kc except for large inductors which are

measured near their natural frequencies. The maximumerror of 20 in dissipation factor and storage factorreadings varies directly with frequency, as does alsothe average error of 5 , except that these errors willnever be less than 3 , which is the error of adjustmentof the D-Q dials.The resistances used in the three D-Q rheostats arechosen to give the ranges stated in Table I at 1 kc. Atlower frequencies the upper limit for dissipation factorwill be less than unity, and for storage factor the Q andQ dials will rot overlap. t higher fre


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more than 16 connected across the R terminals, theD-Q switch e i ~ turned to L-Q and the Q dial turned tomaximum. Althoogh, the switch is in the L-Q position thecircuit is a Maxwell Bridge and thus measures seriesinductance. Storage factor is calculated from the expression Q = 0.628 fR (kc, kn).

Under the same conditions the Q dial must bereplaced by a resistor of more than 160n connectedacross the SERIES RES terminals. The circuit remainsa Hay Bridge and measures parallel inductance. Storagefactor is calculated from the expression:Q = 1:;:2 (kc, kn)

NaI'E: See paragraph 3.41 8) for the relation betweenseries and parallel inductance especially when Q is small.Type 214-A or 371-A Rheostats are recommended asthese added resistors*.

TABLE VValues of Resistance needed for given values of D, Q, and f.DIALf

0.01 kc0.02 kc0.05 kc0.1 kc0.2 kc0.5 kc1 kc2 kc5 kc

10 kc

DD = 0.1160 kn80 kG32 kn

16 kG8 kO3.2 kO1.6 kfl.8 kG.32 kG.16 kG

DQD = 11600 kn800 kO320 kG160 kG80 kO32 kfl16 kG8 kO3.2 kG1.6 kG

4.5 SPECIAL APPLICATIONS

DQQ = 101600 kO800 kG320 kO

160 kO80 kO32 kO16 kG8 kO3.2 kO1.6 kG

QQ =1016 kn8 kG3.2 kn1.6 kO.8 kO.32 kG.16 kO.08 kO.032 kO.016 kO

4.51 A-C Resistance with Reactance: A resistancehaving considerable reactance, such as a transmissionline or electrolytic cell, can be measured by connectingit to the R terminals as described in Section 3.2. Theresistance component is obtained from the reading ofthe CRL dial. The reactance component is balanced outby means of a capacitor placed across one of the bridgearms. Type 219 Decade Condensers and Type 1428-BMVariable Air Capacitor are recommended. * All fourcorners of the bridge are available, being brought outto the pairs of terminals, EXT DET high and G, R highand G, and the single terminal J, as shown in Figure 1.The storage factor of the unknown impedance is in allcases of the form RwC , where R is the resistance ofthe arm across which the capacitance C is placed. Thekind of reactance which can be measured in this mannerand the terminals across which the added capacitor isplaced are shown in Table VIII. The resistances, as* See General Radio catalog for data .

obtained from the reading of the CRL dIal, are seriesfor the capacitor across arm A and rarallel for the otherpositions. The formulae given in Sections 3.31 (10)and (11) and 3.41 8) and 9) can be used for calculatingother resistances not obtained directly.With the added capacitance placed across the Bor N arms, the bridge is suitable for the measurementof the resistance of electrolytic cells.

When this capacitance is }iaced across the P arm,t1w bridge becomes a parallel resonance bridge, andwhen placed in series t becomes a series r e s o ~ n c ebridge. In the two latter positions the P arm is made apure resistance. The parallel or series inductance iscalculated from the formula

L _l_wC

TABLE V nArm Terminals Resistance Q Reactance

9

A EXT DET high J Series AwCA + or LB EXT DET high 8. R high Parallel BwCB - or CN EXT DET G : J Parallel Nw N - or CP Rhigh RG Parallel PwCp + or LP In series Series + or L

4.52 Natural Frequency: The natural frequency ofa tuned circuit or inductor can be found by using an oscillator whose frequency is continuously variable, suchas the Type 1304 Beat-Frequency Oscillator. * The unknown impedance is connected to the R terminals asdescribed in Section 3.2. The bridge is balanced bymeans of the CRL switch and dial and by varying theoscillator frequency. This is best accomplished byusing a Type 1231 Amplifier and Null Detector or theamplifier section of the 650-P1 Oscillator-Amplifier.The reading of the CRL dial gives the rarallel resistanceof the unknown impedance. Whatever capacitance existsacross the R terminals due to the bridge wiring is addedto that of the inductor being mea s ured and lowers itsnatural frequency.

4.53 Parallel Inductance and Resistance: The rarai-leI inductance and resistance of an unknown inductor,such as an iron-cored choke coil or transformer, canbe found by setting the D-Q switch at L-Q, and the Qdial at infinity. An additional resistor is inserted at theSERIES RESISTANCE terminals. The rarallel inductanceis read directly from the CRL dial and switch in theusual manner. The parallel resis tance is the ratio ofthe resistance of the ratio arm controlled by the CRLswitch to the added resistance, multiplied by 1000 timesthe reading of the CRL dial. When the added resistanceis less than 160 ohms, the Q rheostat itself can be used.Its resistance is given in Table VI. Type 214-A or 371-ARheostats* are recommended as this added resistance.

4.54 Parallel Capacitance a nd Resistance: Theparallel capacitance and resistance of an unknown eara-


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citor can be found by setting the D-Q switch at eitherC-D or C-DQ and the D or DQ dials at zero. n additional resistor is connected across the R terminals.The Plrallel caPlcitance is read directly from the CRLdial and switch in the usual manner; and the parallelresistance is the value of the added resistance multiplied by the resistance of the ratio arm controlled bythe CRL switch, as given in Table V, and divided by 1000times the readings of the CRL dial. Type 214-A or 371-ARheostats are recommended as this added resistance.

4.55 D-C Polarizing Voltage for CaPlcltors: A d-cpolarizing voltage can be applied to electrolyt ic caPlcitors in two ways, depending on whether the internal or anexternal power supply is used. For the internal microphone hummer, the p o l a r i z ~ battery must be connectedin series with the calDcitor being measured. It shouldbe connected with its positive side to the right CL terminal marked LOW and its negative side to the negativeterminal of the electrolytic caplcitor. Not more than 200volts should be used. The leakage current can be measured by a mllliammeter connected between the batteryand the LOW CL terminal. For an external oscillator,the direct-current polarizing battery can be placed asjust described or in series with the oscillator. ItscalDcitance to ground is added to whichever side of theoscillator it is connected.

4.56 D-C Magnetizing Current for Iron-Cored Coils:A d-c magnetizing current can be obtained for an ironcored choke coil by connecting a battery in series witha choke coil having a low direct-current resistanceacross the EXTERNAL DETECTOR terminals in IDralleI with the telephones. The magnetizing current canbe read on an ammeter placed in series with the battery.For the L-Q setting of the D-Q switch (Q> 10) allthe battery current PlSBeS through the unknown inductor.For the L-DQ setting there is a second IDth through theratio arm controlled by the CRL switch and the DQrheostat. The resistance of this IDth will usually behigh cOIDplred to that of the circuit through the unknowninductor and CRL rheostat. The actual resistances ofthese paths can be calculated from Table V and the,settings of these rheostats. In case of


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TYPE 650-P1 OSCILLATOR-AMPLIFIER

5.2 RESISTANCE MEASUREMENTSFor both direct- and alternating-current resistance

measurements, the Wheatstone r i ~ e circuit of Figure 1ais used.

5.3 CAPACITANCE MEASUREMENTSA Wheatstone bridge with two resistance arms andtwo capacitance arms, as shown in Figure 1b, is usedfor both C positions of the D-Q switch in the measurement of capacitance and dissipation factor.

5.4 INDUCTANCE MEASUREMENTSFor the L-DQ position of the D-Q switch, the circuit is arranged as a Maxwell bridge and for the L-Qposition of the switch, a Hay bridge is used. Theseare shown in Figure 1c and Figure 1d respectively.

5.5 REFERENCESAll the above circuits are treated in detail inAlternating-Current Bridge Methods , by B. Hague,published by Sir Isaac Pitman and Sons, Ltd., London,and in Henney's -Radio Engineering Handbook , Section 7,

published by McGraw-Hill Book Company, New York.

SECTION 6TYPE 650-P1 OSCILLATOR-AMPLIFIER

6.1 GENERALThe Type 650-P1 Oscillator-Amplifier is designed

especially for use with the Type 650-A Impedance Br idge.t replaces the four No. 6 dry cells and fits into the cabinet compartment which originally housed these cells.This unit operates from a single phase 40- to 60-cyclepower line of either 115 or 230 volts (see wiring diagramfor changing connections to power transformer). *

_ This auxiliary unit contains:1) A 1-kc vacuum-tube oscillator having a controllable voltage output, which replaces the microphonehummer and gives a distinctly better waveform than the

latter. This oscillator is followed by a one-stage bufferamplifier which is connected to the bridge through ashielded transformer designed to minimize the b ridgeerrors caused by terminal capaCitances. The transformer contains separate electrostatic shields aroundthe primary and secondary windings, with a substantialseparation between them. The primary shield isgrounded, while the secondary shield is connected tothat secondary terminal which leads to the junction ofthe A and N arms of the bridge. This arrangementplaces a negligible capacitance of 9 l l l f across thestandard captcitor (0.01 or 0.1 pi bridge arm, and introduces a capaCitance of less than 36 l l l f (4.4 MQ reactance) across the CRL rheostat arm (10 kQ maximum)whence the error introduced is also negligible.

2) A two-stage null-balance amplifier which canhave a flat characteristic or which can be tuned to 1 kc,as selected by a panel switch. This amplifier has a~ u f f i c i e n t and controllable gain to permit the capacitance and inductance bridge circuits of the Type 650-Ato be balanced easUy and precisely by the use of headtelephones or by an external a-c voltmeter having asensitivity of 10 kQ per volt or better.

3) A source c i d-c voltage for energizing the Wheatstone bridge circuit for d-c measurements. This voltage*The plate at the POWER receptacle is etched on bothsides. f the power transformer connections are changed,the plate should be turned to show the correct voltage.

considerably exceeds the 6 volts originally availablefrom the dry cells and permits a more accurate balancein measuring high resistance values up to one megohm,the limit of the bridge.6.2 DIRECTIONS FOR INSTALLATION

1) Remove the bridge from the cabinet.2) Cover each of the spade terminals on the extremities of the battery leads with any suitable insulating tapeand wrap these leads out of the way, say, around thesubpanel supporting post under the upper right-handcorner of the instrument panel. f subsequent use ofbatteries is not contemplated these leads may be cutoff at the points where they are attached to the bridge

circuits.3) A 60 -ohm protective resistor card is mountedacross two terminals on the rear of the GENERA TORswitch of the bricige. When the Type 650-P1 unit is usedwith the bridge, this resistor is not required, and itspresence, under certain conditions, will introduce errors

in the bridge measurements. This resistance should,therefore, be reduced to zero, either by soldering ajumper wire directly across the leads to the card, orby cutting off the two leads close to the card and thenbending and soldering these two leads together.**4) Remove the batteries from the instrument cabinetand pry off the sponge-rubber supporting pads.5) Remove the side panel of the oscillator-amplifierunit and pass the free end of the concentric cable stored

in the oscillator compartment through the large hole inthis panel. Ascertain that all three tubes are securelyseated in their sockets and replace the side ptnel. Thispanel is fastened by three quarter -turn lock screwshaving vertical slots when secured.

(6) By pulling gently, ascertain that the shieldedcable extends its full distance from the auxiliary unit.lnsert the free end of this cable thr ough the hole from**This resistor should be replaced if the bridge is returned to battery operation.


15/29


the battery comlBrtment into the bridge compartmentof the cabinet. Lower the auxiliary unit into the batterycompirtment (with inJKIt socket on the left side) takingup slack in the shielded cable. Secure the unit with thetwo pinel screws which originally mounted the batterycover.7) Support the bridge JWlel in a convenient invertedposition. Without disturbing any of the present wiring,solder the short, insulated lead of the shielded cablefrom the auxiliary unit to the non-grounded EXTERNALDETECTOR terminal of the Type 650-A Bridge. Attachthe long, lug-ti pped lead to the central (grounded) terminal of the CRL rheostat. The free extremity of the

cable has been prepared to facilitate these internalsoldered connections.8) Replace the bridge in the cabinet and fastensecurely with the panel screws.

6.3 OPERATING INSTRUCTIONS6.31 General: 1) Connect the recessed receptacleon the auxillary unit to 50- to 6O-cycle line by means of

the cord IrOVided. The apJiied voltage must be approximately the value specified on the recepacle label. Keepthis power cord at a maximum distance from all bridgeterminals and from the circuit element to be measured.2) Turn on the power switch of the auxiliary unit,which energizes the pilot light. There is a warm -upfrequency rise of less than 20 cps.3) For all uses of the Type 650-A Bridge set theGENERATOR switch on the IBDel of this instrument inthe middle positioo marked EXT. ON-INT. OFF. The DCand 1 KC positions of this switch are now inoperable.4) Avoid bodily contact with the idle EXTERNALDETECTCR terminals 00 the 650-A JllDel while balancingany of the a-c bridges.

6.32 Measurement of D-C Resistance: 1) By meansof the plug-terminated conductor provided, join theand - DC terminals m the awdliary piDel to the EXTERNAL GENERATOR terminals m the bridge pmel. Ascertain that this connectioo is the same as would be attainedby non-cr08slqt wires betWeen these terminals. This willinsure that the galvanometer needle moves in the samedirection that the vernier control knob of the CRL dialis turned, a convenient operating feature. The d-cvoltage thus applied to the bridge will vary accordingto the resistance values of the r i ~ e arms. The regulation of this auxillary unit is such that this voltage willexceed the 6-volt value formerly supplied by the drycells for the measurement of all resistors in excessof .08 ohm, but will remain at all times well within themaximum safe limits for the bridge arms. f desired,this bridge-terminal voltage may be reduced by connecting a suitable external resistor across the DC terminals in parallel with the internal 50 kO resistor. Noharm will result from short-circulti.og the DC terminals.2) Set the BRIDGE INPUT switch on the auxiliary

12

unit in the DC position. In so dOing, both the oscillatorand the amplifier are de-energized while the filteredoutput of the rectifier is applied (ungrounded) throughan internal voltage divider to the DC terminals.3) Operate all other controls on the bridge panelas directed in the instructions for this instrument,

u ~ the galvanometer shunt (DETECTOR switch) in theproper manner.6.33 MeasureJD: nt of Inductance and CapaCitance at aFrequency of 1 kc: 1) By means of the plug-terminatedconductor provided, join the 1 KC terminals of theauxiliary unit to the EXTERNAL GENERATOR terminalson the bridge panel. Ascertain that this connection isthe same as would be attained by non-crossing w iresbetween these terminals.2) Set the BRIDGE INPUT and AMPLIFIER RESPONSE switches on the aux1l1ary panel in the 1 KCpositions. All three switches are thus thrown in anup direction.3) Attach high impedance headIilones or a suitablea-c galvanometer to the PHONES terminals on the auxiliary JWlel.4) Set the DETECTOR switch on the bridge panelin the EXT. position.5) Operate all other controls on the bridge panelas specified in the instructions for this instrument.(6) Adjust the OSCILLATOR GAIN and AMPLI

FIER GAIN controls on the auxiliary panel as desired.In general, the AMPLIFIER GAIN should be set at amaximum in the final balance of the bridge and theOSCILLATOR GAIN advanced only suffiCiently to givea workable sensitivity. This w1llinsure the maximumpurity of waveform from the oscillator.Reducing the OSCILLATOR GAIN to the lowestworkable limit will permit iron-cored inductors to bemeasured as close to initial permeability as possible.

6.34 Measurement of Inductance and Capacitance atOther Frequencies: The l-kc oscillator of the auxiliary UDlt may e reIiaced by any suitable external sourceof a-c voltage of the desired frequency while the amplifier in the auxiliary unit is used with headIilones or ana -c galvanometer as the null detector.(1) Remove the external connection between thepanels of the bridge and the auxiliary unit.2) Connect the external generator to the EXTERNALGENERATOR terminals of the r i ~ e thrmogh a suitableshielded transformer (such as the Ty pe 578-A). SeeSection 4.2 regarding this procedure and for safe limitsof applied voltage.3) Turn on the auxiliary unit and set the BRIDGEINPUT switch in the 1 KC position (to energize theamplifier) .4) Set the AMPLIFIER RESPONSE switch at theFLAT position, which provides greater sensitivity butwhich has no inbereJt selectivity. f needed, some selectivity and increase in gain may be given to the FLAT am plifier, when u s ~ teleIilones at frequencies below 1 kc,by adding an external adjustable caplcitor in parallelacross the PHONES terminals to resonate the inductivereactance of the phones at the frequency used. The


16/29

TYPE 650-P1 OSCILLATOR-AMPUFIER

rectifier-type galvanometer cannot be tuned in thismanner and should be used without added capacitance.5) Set the DETECTOR switch on the bridge panelin the EXT position.(6) Operate the bridge-balancing controls in thenormal manner, noting that a correction must be appliedto either the D or Q dial used in accordance with thefrequency of the a -c voltage employed, as described inSection 4.4.

6.35 Other Uses of the Auxiliary Unit: t will beevident that the auxiliary unit is a self -contained assembly comprising a 1-kc oscillator and a flat or a 1-kcamplifier which may be used separately or jointly, inany suitable manner with other laboratory equipment.Likewise this unit may serve as a source of limitedd-c power but not simultaneously as an amplifieror an oscillator.To use the amplifier and/or oscillator separatelyproceed as follows:

1) Remove all external connections to the 650-Apanel.(2) Set the bridge GENERATOR switch in the DCposition to minimize pickup on the GENERATOR terminals.3) Set the bridge DETECTOR switch in the GALV.position to isolate the EXTERNAL DETECTOR terminalsfrom the bridge circuits.4) These EXTERNAL DETECTOR terminals thenbecome the inp.1t of the auxiliary unit amplifier. Connections to them should be made through a concentric

shielded cable preferably fitted with a shield cap suchas the Type 274-NE Connector. The shield should, ofcourse be connected to the grounded EXTERNAL DETECTOR terminal.(5) Energize the auxiliary unit and use either theFLAT or the tuned 1-kc amplifier as desired.6) The 1-kc oscillator is simultaneously in operation and may be used if desired. Neither terminal ofthe outp.1t transformer is internally grounded, but either

may be grounded.To use the d-c power supply unit separatelyproceed as follows:

1) Energize the auxiliary unit.2) Set the BRIDGE INPUT switch in the DC position.3) Apply the external load across the DC terminals.The regulation of this power supply is then very

closely linear between the limits of 190 volts with zeroload current, and zero volts with a maximum load currentof 8 milliamperes when the load has essentially zeroresistance.

f the desired terminal voltage for a given loadcurrent is less than the value specified by the equationE(volts) =190 - 22.6 I (rna)

a suitable shunt resistor may be added externally acrossthe DC terminals. This will of course improve theterminal voltage regulation for any given change in theresistance of the external load.

SERVICE AND MAINTENANCE INSTRUCTIONSFOR THE

TYPE 650-A IMPEDANCE BRIDGE1.0 FOREWORD1.1 These Service Instructions together with the information given in the Operating Instructions should enable theuser to locate and correct ordinary difficulties resultingfrom normal usage.1. 2 Most of the components mentioned in these notes canbe located by referring to the photograph.1.3 Major service problems should be referred to theService DeIllrtment which will cooperate as far as possible by furnishing information and instructions as wellas by shipping any replacement parts which may berequired. f the instrument is more than one year old,a reasonable charge may be expected for replacementparts or for complete reconditioning if the bridge isreturned.1.4 Detailed facts giving type and serial numbers of theinstrument and parts as well as operating conditionsshould always be included in your report to the ServiceDepartment.

13

2.0 GENERAL2.1 f the bridge fails to function, check the position ofthe bridge controls and the condition of the sample undermeasurement before attempting to locate trouble in thebridge. Failure to obtain a balance may be due toreasons which lie outside the bridge for instance anopen circuited resistance sample. This situation can bechecked by measuring a standard of the same order ofmagnitude which is known to be in good condition. akecertain that the magnitudes of impedances of the samp,esunder test do not lie outside the range of the bridge.2.2 From time to time all switch blades contacts, andthe contact surfaces of the four rheostats should becleaned. A solution of half ether and half alcohol isrecommended. A clean cloth may be used on exposedsurfaces and stiff white paper where the cloth is inconvenient. No abrasives should be used on any contactsurface. A thin coat of Lubriko MD grease or equivalentshould be applied to all bearings and to switch contacts.No lubr icant should be used on the rheostat contactsurface s.


17/29


3.0 BRIDGE INOPERATIVE3.1 D-C resistance measurements, refer to Section 4.0.3.2 A-C resistance measurements, refer to Section 5.0.3.3 C a ~ c i t a n c e measurements, refer to Section 6.0.3.4 Inductance measurements, refer to Section 7.0.3.5 Calibration of dials, refer to Section S O3.6 MicroIilooe hummer inoperative, refer to Section 9.0.

4.0 D-C RESISTANCE MEASUREMENTS4.1 Refer to Figure A which shows components of bridgeused with this circuit. External batteries can be usedi required but their voltage should NEVER exceed thelimits shown in Table IV of the Operating Instructions .4.2 Test batteries for proper voltage. This should be.done using a voltmeter.

4.21 Proper battery voltage under load is 6 volts, d.c.4.22 Batteries can be checked as follows withoutremoving battery c o m ~ r t m e n t cover.4. 221 Turn switch 8-6, DETECTOR, to EXT.CAUTION: Do not turn DETECTOR switch duringtest or excessive current will flow through the galva

nometer, causing damage to i t4.222 Turn switch S-4, GENERATOR, to D-C .4.223 Connect the positive lead of the voltmeterto the R high) binding post, the negative lead to the I

binding post.4. 3 Galvanometer will not come to zero.

4.31 Examine w 1 r ~ to be sure that no short circuitsa r e present or that wiring is oot touching copper shieldingof the cabinet.4.4 Galvanometer is defective .

4.41 I f the meter is defective, a replacement shouldbe ordered from the Service D e ~ r t m e n t The GeneralRadio Company cannot assume responsibility for anylocal r e ~ i r s to the meter, although such r e ~ i r s maybe necessary in an emergency.4.5 Check all switches for proper contacts and operation.Refer to Section 2. 2.4.6 Test resistors R-1 through R-10 and R-14 for openand short circuits and proper values .

4.61 Resistors R-1 through R-S, as well as S- l

to R. An ohmmeter or Wheatstone bridge can then beconnected to either the I or R high) binding posts andthe EXTERNAL DETECTOR high) binding post andmeasurements made .

4.62 Test rheostat R -10 for continuity and properresistance values corresponding to CRL dial settings.4.621 R-10 can be checked from the panel bysetting the DETECTOR switch to EXT, the GENERATOR

switch to EXT ON-INT OFF and the D-Q MULTIPLIERswitch to L. Connect a Wheatstone bridge from bindingpost I to one of the ~ e l grounds. Resistance readingsshould be 1000 times the dial reading . I f the dial calibration is incorrect, refer to Section S.O.

5.0 A-C RESISTANCE MEASUREMENTS5.1 Refer to Figure B which shows the components ofthe bridge used in this circuit. Circuit shown uses theinternal 1-kc generator. An EXTERNAL GENERATORcan be used. (For switch S-4 settings see Figure D.)CA UTION: Do not exceed the s afe voltage limit sgiven in Table V of the Operating Instructions.5.2 Test batteries; refer to Section 4.2.5.3 Check all switches for proper contacts and operation;refer to Section 2.2.

5.31 SWitch S-3 is located on the shaft of the CRL MULTIPLIER switch and changes the connections onthe mlcroIilone hummer to keep the impedance matched.The cam should be set on the shaft so that the camfollower is down toward the shaft) on the 0.1- anQ I-ohmswitch positions, and up away from shaft) on all higherswitch positions.5.4 Test resistors R-1 through R-S and R-10 for openand short circuits and proper values . Refer to Sections4.61 and 4.62 .5.5 MICROPHONE HUMMER does not function proper ly.Refer to Section 9.0.

6.0 CAPACITANCE MEASUREMENTS6. 1 Refer to Figure C which shows the components ofthe bridge used in this circuit . Ci r cult shown uses theinternal 1-kc g e n e r a t o r ~ An EXTERNAL GENERATORcan be used. (For switch S-4 settings, see Figure D.)CA UTION : Do not exceed the safe voltage lim it sgiven in Table V of the Operating Instructions.6.2 Test batteries ; refer to Section 4.2.6.3 Check all switches for proper contacts and operation;

r e f ~ r to Section 2.2.can be conveniently check ed from the ~ e l of the bridge 6.4 Test resistors R-1 through R-6 and resistors R- 10 ,by setting DETECTOR switch to EX T , GENERATOR R - l l , and R - 13 fo r open and short circuits and proper

OWIt {tO/::J'1Nrp : : : ~ : : / ; ~ =h : ~ u e ~ * :u; ;n{ Ji~ B . . t . ~ d t ~ i ox :JJe ~ ' A Jm W ~ ~ ~ ~ t Y n t t ~ r


18/29

J

GENERATOR

~ S 4

6 VOLTS

I ENERATORDCLOWC-Lo

-2

..--_=::: _1.... N>r---. a

D.C. RESISTANCEFigure A_

R-14DETECTOR

ALV.

CAM OPERATEDFFp-1 5-1 r ~IKCIENERATOR

VOLTS

R-I-2

R-3

Rt--- II I r--J L? -f R-6

---Q----- :: \...----- -- - - - - - ~ ~ I 5 2

A C RESISTANCE - IOOCkv INT)Figure B_

R

EXT.


19/29


6.5 Test capacitor C-l for an open or short Circuit,leakage and proper value.6.6 MICROPHONE HUMMER does not function properly;refer to Section 9.0.7.0 INDUCTANCE MEASUREMENTS7.1 Refer to Figure D which shows the components ofthe bridge used in this circuit with an external sourceof a-c voltage. The internal l-kc generator can be used.For switch S-4 settings see Figure C.)CA UTION: Do not exceed the safe voltage limits .given in Table V of the Operating Instructions.7.2 Test batteries; refer to Section 4.2.7.3 Check all switches for p-oper contacts and operation;refer to Section 2.2.7.4 Test resistors R-l through R-6, R-9 through R-12for open and short circuits and proper values; refer toSeetions 4.61 and 4.62.7.5 Test capacitor C-2 for an open or short circuit,leakage and proper value.7.6 MICROPHONE HUMMER does not function properly;refer to Section 9.0.8.0 CALffiRATION OF DIALSThese calibrations must be made using a Wheatstone bridge accurate to at least :to.25 .8.1 Main CRL dial.

8.11 Make certain that the rheostat, R-I0, is clean,that the set screws are tight, and that the cam followermechanism is operating freely.8.12 Remove one connection to R-I0, and connect theWheatstone bridge to the rheostat. The resistance, inohms, measured y the bridge should then be 1000 timesthe setting of the CRL dial.8.13 Turn the main dial to a point near the centerwhich brings the cam follower opposite one of the camplate screws, and adjust the screw until the resistancein ohms is 1000 times the dial reading. Progress up

the scale and then down the scale, adjusting each screw

in a similar manner. As a final check see that eachmain point on the dial and also points 0.5 and 0.1 checkwithin 0.5 of the correct resistance value. f i t isfound that the whole cam plate is adjusted too high ortoo low, loosen the set screws in the dial, shift its position on the shaft, and start the cam plate adjustmentover again.8.2 D D-Q, and Q Dials.

8.21 Calibration of these dials consists simply insetting a single point to the correct resistance. Afterthe rheostats have been cleaned, set the D-Q MULTIPLIER switch at R and connect the Wheatstone bridgeto the terminals of each rheostat in turn, setting thedials as shown below. Dial CorrectDial Setting Resistance

D 2.5 398 ohmsD-Q 2.5 3980 ohmsQ .5 31.8 ohmsf these resistance ~ s are not obtained, loosenthe dial set screws and change the dial positions untilthey correspond to the correct resistance.

9.0 MICROPHONE HUMMER INOPERATIVE9.1 Test batteries; refer to Section 4.2.9.2 Check switch S-4 for proper connections and operation; refer to Section 2.2.9.3 Test capacitor C-3 for a short circuit and leakage.9.4 Test the coils of the hummer for open circuits orshort circuits to ground.9.5 f the hummer refuses to start when measuringsamples of low inductance, the air gap of the reed canbe decreased slightly by turning the adjusting screwin a clockwise direction. This tends to increase theharmonic output of the hummer which, i f raised to toohigh a value, makes it difficult to detect the null balanceand so is recommended only as an emergency measure.9.6 f the hummer is completely inoperative, it shouldbe removed from the bridge and returned to the factoryfor repair and reconditioning.

SERVICE AND MAINTENANCE INSTRUCTIONSFOR THE

TYPE 650-Pl OSCILLATOR-AMPLIFIER1.0 FOREWORD1.1 These Service InstructiODS together with the information given in th Operating Instructions should enable theuser to locate and correct ordinary difficulties resultingfrom normal usage.

16

1.2 Most of the components mentioned in these instructions can be located by referring to the photographs.Special instructions for disassembly of the instrumentto replace component parts are given in Section 9.Q.1.3 Major service problems should be referred to the


20/29

CAM OPERATEDFROM 5 1 . u: ., 54

R I R-2R-3

R-5J C R-6 JR

CRL R IO

EXT.

~DETECTORCAPACITANCE - 10001 V( INTI

Figure C.

12. II10 9 5 4B .7

R-9 6 5 IXT. ON4 INT. OFF2GENERATOR

EXT.GEN .

R I-2

.rIex R 5R-6

INDUCTANCE - EXT. GENERATOR

Figure D.

R00

EXT.

6 ~ 5 6 J I


21/29


Service Department which will cooperate as far as possible by furnishing information and instructions, as wellas by shipping any replacement parts which may berequired. If the instrument is more than one year old,a reasonable charge may be expected for replacementparts or for complete reconditioning if the unit isreturned.1.4 Detailed facts giving type and serial numbers of theinstrument and parts, as well as operating conditions,should always be included in your report to the ServiceDepartment.2.0 GENERAL

If the oscillator-amplifier becomes inoperative,a few simple checks should be made before removingthe metal side panels.2.1 Check the power line source.2.2 Check the power supply cord fot open circuits orpoor contact in power outlet.3.0 INSTRUMENT INOPERATIVE3.1 See that all tube filaments are lighted.3.2 If the pilot lamp does not light, see Section 4.0.3.3 No d-c output at d-c terminals, see Section 5.0.3.4 No output at 1-KC terminals, see Section 6.0.3.5 No amplification, or low amplification, see Section 7.0.4.0 PILOT LAMP DOES NOT LIGHT4.1 Check bulb P-l.4.2 Check R-26.4.3 Check connections on transformer T-l.5.0. NO D-C OUTPUT AT D-C TERMINALS5.1 See that BRIDGE INPUT switch Is set at D.C.5.2 Test resistors R-2, R-3 and R-27 for open circuitsand proper values.5.3 Check BRIDGE INPUT switch, S-2 for loose ordirty contacts.5.4 Check power supply; see Section 8.0.6.0. NO OUTPUT AT 1-KC TERMINALS6.1 See that BRIDGE INPUT switch is set at 1-KC.6.2 Test tube V-2 and operating voltages. See Section 6.6.

18

6.3 Test transformer T-2 for open circuits and continuity.6.4 Check resistors R-5 through R-15 and R-25 foropen circuits and proper values.6.5 Check capacitors C-5, C-6, C-8 through C-12 foropen or short circuits and leakage.6.6 When tube V-2 is replaced, the two internal adjustments R-14 and R-13 may, in rare instances, requirereadjustment. The side panels must be in place whenthese adjustments are made.

6.61 Line voltage should be 115 or 230 volts A.C.Move R-14 over its entire range. If this gives output,set R-14 at the point where 12 to 15 volts rms (1000cycles appears at the 1-KC output terminals with noexternal load. This voltage .should be measured witha high-impedance-input vacuum-tube voltmeter.6.62 Turn rheostat ~ 1 3 in a clockwise directionuntil oscillations begin as indicated by a 1000-cycle noteat the 1-KC output terminals. R-13 should not be ad

vanced much beyond the point where oscillations justbegin as the ootIUt waveform will become mdly distorted.NOTE: Setting of R-13 can be increased slightly tomaintain oscillation i the line voltage decreases to 105volts.

6.63 R-14 should now be reset as in Section 6.61.7.0 NO AMPLIFICATION, OR LOW AMPLIFICATION

A signal of 10mv, at 1000 cycles, applied at theends of the input cable should give 4 v at the PHONEterminals on open circuit with AMPLIFIER RESPONSEswitch set at 1-KC and AMPLIFIER GAIN control fullon. With AMPLIFIER RESPONSE switch set at FLAT,this output voltage should be 6 to 9 volts.7.1 Check tube V -3 and operating voltages.7.2 Check AMPLIFIER RESPONSE switch S-3 for looseor dirty contacts.7.3 Test resistors R-4, and R-16 through R-21 foropen circuits and proper values.7.4 Test capacitors C-4, C-7, C-13 through C-16 foropen or short circuits and leakage.7.5 When no output appears with the AMPLIFIER RESPONSE switch set at 1KC:

7.51 Test resistors R-22 through R-24 for opencircuits and proper values.NOTE: R-22 R-23 = R-24 :to 5

7.52 Test capacitors C-17 through C-19 for openor short circuits and leakage.NOTE: C-18 C-19 = C-17 :to 5


22/29

TYPE 650-Pl OSCILLATOR-AMPLIFIER

8.0 POWER SUPPLY8.1 Check switch S-1 for loose or dirty contacts.8.2 Check transformer T-l for open circuits and continuity.8.3 Test tube V-I and operating voltages.8.4 Test resistor R-l for open circuit and proper value.8.5 Check capacitors C-l through C-3 for open orshort circuits.9.0 REPLACEMENT OF COMPONENTS

Owing to the compact design and construction ofthis instrument and the number of component partsmouflted in the available space it is necessary to usea number of mechanical expedients. This makes removal of parts for testing or service difficult withoutfollowing specific instructions. The instrument isdivided into three sub-assemblies; namely, power suwiY,amplifier and oscillator and referred to as SA-I SA-2,and SA-3 respectively in these instructions and on thephotographs. Care should be taken to replace disconnected wires and components in their proper placeswhen reassembling.CAUTION: Soldering should be done with the instrument lying on its side. Use care to avoid droppLng sm llbits of solder into the instrument as these can causeshort circuits resulting in serious damage.9.1 Power Supply, Subassembly SA-I.

9.11 Remove the two hexagonal panel screws o l ~the POWER receptacle.9.12 Unsolder connections shown on photographlabeled SA-I.9.121 Green-yellow wires to power socket.9.122 Tan wires to D.C.+ and S-2.9.123 Orange wires to terminals 7 and 8 of V-2

socket.9.124 Black-red wire to terminal 4 of S-2.9.125 Black-green wire to terminal 3 of S-2.-9.126 Resistor R-26 at ground lug.

9.13 Remove the two small binder head machinescrews on bottom of SA-I.9.2 Amplifier Subassembly SA-2.

9.21 Remove the two hexagonal panel screws at rightend of panel.

9.22 Remove AMPLIFIER GAIN control knob.9.23 Unsolder connections shown on photographlabeled SA-2.9.231 Orange wires to terminals 7 and 8 of V-2socket.9.232 Black wires to ground terminal on SA-3 .9.233 Capacitor C-16 to high PHONE terminal.9.234 Black-red and black-green wires to SA-3.9.24 Remove switch S-3 from panel.9.25 Remove the two binder head machine screwsOPPOSite those mentioned in Section 9.13.

9.3 Oscillator Subassembly SA-3.9.31 Remove SA-l and SA-2.9.32 Remove OSCILLATOR GAIN control knob.9.33 Remove the two hexagonal panel screws atcenter of panel.9.34 Unsolder connections shown on photographlabeled SA-3.

9.341 Solid, bare wires to S-2.9.342 Insulated wires to l-KC output terminals.NOTE: Care should be taken to replace theseleads in exact positions as located before their removal.This is necessary to minimize capacitance to ground.

10.0 VACUUM-TUBE DATATable of tube socket voltages measured from socketpin to ground unless otherwise noted u s ~ a 20,000 ohmper-volt meter Westoo 772 Analyzer). D-C voltages may

vary as much as .20 .Symbol Type Socket Pin Number Function

V-IV-2V-3

2 3 4 5 6 8H 6.7 (AC) 150 300 1506SL7GT 235 3.4 300 3.6 6.7 AC)6SL7GT 200 2.? 200 2.25 6.7 AC)

CONDITIONS:POWER switch ON , 115/230 v. 60 cycle 10 watts.BRIDGE INPUT switch at 1 KC.AMPLIFIER RESPONSE switch at KC.

RectifierOscillatorAmplifier

OSCILLATOR GAIN and AMPLIFIER GAIN at maximumclockwise positions.No external connections to instrument terminals.

19


23/29


F ;; ;,-:r---BPIDGE -=

4MPlIFIERGAINElementary Schematic Diagram of the

Type 650-Pl Oscillator-Amplifier

RES I STORSR I = 1170 Oh t l O ~ REC20BFR 2 = I . K Oh t 1 0 ~ RECIU BFR3 = ..7000 Oh t l ~ REC30BFR .. = ..70 Oh t l O ~ REtZOiFR . 5 = ..70 Oh., i : 1 0 ~ RECZOBFR.6 = o. I Megeh. i: 1 0 ~ REC- JOB .FR7 := Melloh", t I 0% R.EC-ZOBfR8 = I Megoh. i : 1 0 ~ 1 I E ~ . Z G 8 fR9 = 50000 Oh. , PO C 'HIO = 178 K Ohll' t I ) RHIR- II = 178 K Ohll' t REF-IR-12 = 22000 Oh tlO1- REC-ZOBFR-13 = 50000 Ohu t 2 0 ~ PO SC \IRI .. = 1000 h tl010 PO SW .. 3H. I i = IZOO Oh i : 1 0 ~ REC-Z06FR-16 = 0.1 Megohll POSC-7h i ? = 0.1 MeOoh. i:101o REt-201fR. 18 = O. I Megoh. i:101o REt-20BF1 . 20 = 1200 Oh i:IO% REC .. 20BFh21 = 108 "egoh tlO% REC-20BFR. 22 = 110 K Gh t REF-IR ~ 2 3 = 160 K Oh i: 11- REF-I1.2 . = 80 I Oh i: 1% REF-II . i i = 180 Oh i:10f; REW3eR- 26 = 15 OhM tl010 REIIae1 . 27 = Ia k Oh i:"% REC.'I BF

I .. 22 + R23 = R. illIl i : 0 ~ 6 ~ by SELEtTl 011TUIUYI = ICA Sill -2 = ICA ISL7iTv-' Y.a :: ICA 1SL71T

TOP VIEW OF INSTRUMENTPD ,' TUBE LAYOUT

20

CO'l =C . 2 =C . 3 =C ...C . 6 =C . 5 =C .7 =C"8 =CII =*'*C-IO =:(;fC .. j l =

**C . 12 =C. J3 =C . . . =C.15 =C . 16 = C"17 -C 18 =; >. Co 19 =

.... I ,.. Pl . 1 =

T-I =h 2 =S.I =S . 2 =S3 =

~_ ___ ~ A r N E N1'ItQM

I . rllNED AItII CIf(ReMOVED nJII FLATAMI'L 'Cp)

COIIDEJISEaS:0 IJ.f '50 l)CWV C O E ~ i20 IJ.f} 1650 DeWY CO8.202020 IJ.f} '50 DCWY CO8.2020 IJ.fao IJ.f 150 DCIIY COh8200 fo'f 10 OCWY COE .. 6

0.Q2 ",f t l ~ COM-50B0.005 IJ.f t l O ~ COM-3580.002 IJ.f i:0.001 IJ.f t 650- 390.001 IJ.f t0.0" IJ.f t l O1- COM-50B0.005 COM-35S0.02 /jf t l O ~ COM-50B0.01 /jf i:IO% CCM-1t1B0.002 /jf t 2 J0.00 I IJ. f t 210 650-390.001 i:

1 If SCELUI EDU SPi lo t Lilli t 2LAP ..U9Mazda No. 20Plug ZCDPP- 1OTrill . to r .e r 8166 .......Trl l l . fer .er H 6 . 1I07Switch Drn SNT .. aU, .PSwitch DPDT & I I T ~ liPh i t ch DrST Sl/hal i

S e l e e t ~ ~ Cr l t lc l l Value,C"18 + C"19 = C . 17 to. 10 by SELECTIONC . II + C"12 = C-IO to.6;4 by SfLECTION


24/29

I ;O R -I 5 or2JOVOLTS150 - 6(} r J

T IF or 115 op,ro/ion

C Dnn,c l I fo J 8 ? ~ / = 4 _ - 4 ~For 230

Connt c l 2 to 3

II _

100

general radio gr-650 operation and maintenance manuial

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