INSTRUMENTS FOR ELECTRICAL MEASUREMENTS AT COMMUNICATION FREQUENCIES F ILE THIS WITH C ATALOG F and PART l Revised to October 1. 1931 GENERAL RADIO COMPANY CAMBRIDGE A. MA.SSACHUSETTS BEFORE ORDERING please consult the indexes at the back of this booklet for reference. to additional information about the instruments you plan to purchase. The indexes previously published are obsolete. • Additional copies of Catslog F. Part 1. and of Catalog F. Part 2. are available if you need them to com· plete your files. We shall be glad to send either ODe or both by return mail if you will ask for them. Please mention your business affiliation to help us in tracing your name in our mailing list records. COPTRIOBT. 19S1 BY THE GE."lERAL lUDIO CoUPANY FOREWORD TO PART 3 Catalog F, the complete catalog of General Radio lab­ oratory apparatus, now consists of t hree parts: 1. Catalog F, Junc, 1930 (known as " Part 1"). ~. Catalog F, Part Q, April, 1931. 3. Catnlog F, Part 3, October, 1931 (this booklet). All previous catalogs and catalog supplements are obso­ lete and should be destroyed or marked "obsolete" to avoid possible confusion. I n the meantime, catalog supplements of the serIes 1"-400, }-'-401,'F -402, etc., will be issued from time to time as the need ari ses. They will be announced in the General Radio Experimenter. 'Vatch for them. [ 169] TABLE OF CONTENTS FOR PART 1, PART ~, AND PART 3 I. COND ENSERS .......... .... .... ....... .... 5, 1 ~3, 171 n. U }O;S ISTANCE DEVICES .... ................. 15, 126, 174 III. I NDUCTORS .................................. 31, 129 IV. O SC i LLATOnS ... ............................. S5, 130, 181 V. AMPLIFIERS, COUPLING D ~;v l c ,,:s , P OWER-SUPPLY 42, 133, 183 VI. FI~EQUEN CY- AND TIi\IE-l\1 EASUUlNG D EVICES.. 51, 184, 18G VII. BRIDGES AND THJ.;IR ACCESSORI ES............... 74, 141, 191 Ylll. R ADIO-FUEQUF;XCY T" ;S TI~G DEVICES... .. 88, 143, 194 IX. ,MISCELLANEOUS LABOHATORY E QU IP"'J.':NT . ...... 93, 150, ~03 X. l\iETERS . ........................... 00 , 1 5 '~ , 213 XI. R J.; I, AYS. SWITCHES, AND MISC ELld.N J.;OUS A CCES- SOIUJ.;S .. ..... ... .. ................... 108, 157 I ~ I)f; X IlY TYPE NmlBER .. 224 I N DEX BY TITT~}O; . 226 [ 170 1 CONDENSERS HE following chapter describes three new additions to OUf line of variable air condensers. TT he TYl'E 222-1Vr Precision Condenser is a unit calibrated to read directly the capacitance diO'crence between a given setting near maximum and any other setting. It is designed for usc in making measurements oC capacitance by the substitution method. The TYl'E 539-T Variable Air Condenser is a straight-line-frequency model of the condensers described on page 123. It is recommended for usc in laboratory work where a fairly close adherence to lhe straight-line law is desirable. The TYPE 568 Variable Air Condensers arc small units designed fol' short-wave circuits. T YPE flflfl-M PRECISION CONI)ENSEIl illS condenser bas been designed to provide a di rect-reading, adjustable standard of Tcapacitance for use in the substitution measurement* of capacitance. In this method, which is ideal for small values of capacitance, the calibrated standard is placed ill parallel with the unknown. '.I'wo balances are required, the unknown capaci­ tance being given by the difference between the values of the standard when the unknown is connected and when it is discOllllected. The 1'1'11E 2~2-l\:[ Precision Condenser is arranged so that the capacitance difference may be read directly from t.he engraved scale, thus eliminating the use of a calibration chart and the computation of the unknown capacitance by subtraction. Zero scal c reading corresponds to nearly maximum capacitance (about 1200 IJIJ£), the first bridge balance being taken with this selling. The scale reading for the second balance may extend to a maximum difference capacitance of 1000 1J1Jf, corresponding to an actual capacitance of about 200 1J1Jf. The micrometer drum is div ided into 100 divisions, each corresponding to a change in capacitance of 11J1Jf. Ten turns of the drum cover the range of the instrument. The mcchanicaJ construction of the condenser is similar to that of the TYPE 222-L }lre_ cision Condenser, described on page 6. The differences consist in the use of a 25:1 worm, a. reduced number of plates, and means tor the adjustment (in our laboratory) or two of these plates to give the desired calibration. Range: measurements at 1000 cps., the exact valuc Change in ca.paeitance. 1000 IJlJf; capaci­ being given with each instrument. tance at zero seale reading about l ~O O IJlJf, Drive: the exact value being giveu with each in­ Gear and spring-pressed worm lapped ill strument. position to remove backlash. Ten tucns of Rotor Plates: the worm cover the entire range or the COIl­ Straight-linc capacitance (semicircular). dellser. The micrometer drum is engraved Insulation: witll 100 equally spaced divisions. Isolantitc blocks; mica wi ndow for high­ Bac.:lda sh: Jlotentialtcrminal. Less than Y2 of one division. Figure oj jJfe rit: Calibration: 12 RwC2 is abou t 0.06 x 10- based on Each of the 100 divisions 011 tIle microm- • Genernl Radio &perillllmter, Jalluary, Hl50, p. 5, and Instruction Book for '1'1" 1'1:: 216 Capneity Bridge, pp. 5-0. [ 17J 1 172 GENERAL RADIO COMPANY clef drum corresponds to 1 J.l.J.l.f. Each Carrying Ca3c: condenser is individually adjusted in our Each condenser is supplied in a storage laboratory so that all values of incremental case made of whitewood and filled wilh a capacitance are accurate to within I llJl.f or lock and carrying handle. 0.1% of the maximum. Divisions arc spaced Dimc1!$io1l3: sufficiently to permit estimating to tenths 9Y2 (length) x 87.( (width) x OM (height.) (one part in 10,000) with practice. inches, overall . M Olllltillg: 'Veight: Aluminum panel finished in black crackle l ' ~.!4 pounds ror the mounted condenser lacquer, mounted in copper-lined walnut only, 24 pounds with the carrying case. cabinet. Ca1!hciIUIICC Cod, Type lumge W",d P rice 2'l'l-M 1000 ppr I .. I {."()RRA $100.00 TYPI ~i 539-1."' VARIABLE AIR CONDENSER IUS is a stmight-Iine-rreq uency condenser whieh is similar in most details of construc­ Ttion to the straight-line-capacitance models dcscribed on page 123 . Complete data describiug the straight-line-treq uctlcy variation of t his unit are given in the follow ing specifi cations. Capacitance RCIIIge: (based on measurements a.t 1000 cps.). SO J.lJ.If to :;00 J.lJ.If. These arc nominal Drite: valucs. Each condenscr has actual capaci­ 'Vhen mounted on a panel, the %-i neh tance valucs greater than the maximum and steel shaft extends beyond the back face tess than the minimum, respectively. or the panel enough to attach a dial. No Rotor Pt(tles: knob, dial, or friction drive is included, but Plates arc eut to give a. straight-linc­ the use or the Tn}; 503-G Dial is recom­ trC<llIency variation over 2500 or a possible mended. ~ 700 angle of rotation when a capacitance Calibration: or 2:; J.lJ.lf is connected ill parallel with t he No calibration is include<1. condenser. They arc assembled on t he sh aft so that counter-c1oekwisc rotation produces AI OU1!ti1! 9 : an increase in frequency. T his condenscr is carrie<1 in stock un­ mounted without panel or cabinet. A dri ll ­ FTequency Ratio: ing template is furnished. 3 to 1. starting from a condenser mml­ Mounted models, similar to the '1'\'J'E mum of 50 J.l.J.I.f. 5S9-A, Typf: 599-13, and TYp~"! 539-C Va­ 111.,ulat-ion: riableAir Condensers,dcscribe<1 Oil page I )lS, T wo bars of isolalltitc, specially treated can be built to order. Prices on request. to prevent absorption of moisturc. support Dimensions: the stator assembly. This unit extends 7 Y8 inches behind a AI axim1l11l VoUage: panel and requires a panel space 5}1 inches 550 volts. breakdown. square. Figure of Mer·it: IIIeigh t: RwC 'J is approximately 0.03 x 10- 12 2% pounds. Capacitance Maximum. Code Type .M(U"imum Mi"imum Voltage MOI,lIIting Word Price 5S9-T I 500 ""r 1 so ""r \ 550 volts I Unmounted L......... \ Cl.os£ SH!.OO CONDENSERS 173 T YPE 568 V ARI ABL E A IR C ON DENSERS HESE arc condensers of rugged construction for use as tuning elements in sh o rt-~\' nve Trecei\'crs, transmitters, and wavemeters. They arc designed for tandem mounting, a ho llow sindt permilLi ng the usc of a single long bakelite or metal shaft for driving several units. The isolantitc end plates help to keep the losses at a min imum. Hal/Uc: thickness between U and ~{6 ill(!h. Drill ing Two sizes arc available. Sec the price list. template and three flathead machinescrc\\'s Rolor Plates: arc furn ished. Straight-line capacitance for the 'fn'E DimclIsions: 568.]) and straight-li ne frequency for the Panel space, 2)4' x 2% inches required. T1'PE 5GS-I< Variable Air Condensers. Overall depth behind panel (exclusive of I nsulution: the shaft), 2~ inches. IsolantilC end plates. Weight: Max illHl1n Voltage: %' pound. 500 volls, peak. ""if/lire of Merit: RwC:! = 0.03 x 10- 12 based on measure­ ments at 1000 cps. Drive: The rolor is attached to a hollow shaft through which a Ys -inch insulating or con· ducting shaft m ay be sl ipped und fastencd with two set screws.