THE GENERAL RADIO Experimenter
VOLUME 40. NUMBER 8 / AUGUST 1966
IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 Volume 40 · N o.8
A1.lgust 1966
the ~ Experimenter
Publlehed monthly by the General R adio Company THIS ISSUE ______....,
Page The Improved GR874 Slotted line ...... ,...... 3 Impedance-Malching Tune" for Precision Coaxial.Measuring Systems... 6 TEII"Mode Resononces in Precision Cooxial Connectors...... 10 New Decade Copocilor-Wide Range, High Resolution ...... 14 A 1O·pF Reference Standard Capacitor .•....••..•••.••...•••..•.. 17 Increased Frequency Resolution for Wove-Analyzer Recordings of Vibra- tion, Acoustic, and Electrical Signols ... •...... 18 locating Submarine Cobles ...... , ...... 21
GENERAL RA 0 I 0 COMPAN Y We s t Concord Massachusetts 01 78 1
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GENERAL RADIO COMPANY (OVERSEAS), 8008 Z .. r lc". 8wll~ ••I ."d GENERAL RADIO COMPANY (U.K.) L IM ITED. Oour... I!"d. O"ckl"II".m."lr• . I!ng •• " .. RI!PReSENTATIVES IN PRINCIPAL OVI!:RSEAS COUNTRIES
IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 THE IMPROVED
GR874 SLOTTED LINE
The slotted line is the traditional also be used as a precision phase shifter workhorse of the microwllve measure a nd as a wavemetcr ment industry. It ca n be used to meas The slotted line can also be employed ure a great number of parameters, over for accurate sweep-frequency measure an extremely broad band of frequencies ments of vswa', performing the function of a rcflectometcr over II. wide frequency and with good accuracy. The slotted range. line has its own internal impedance OR manufactures two slotted lines, reference, an accurately constructed one based on the ORS74 connector, the coaxial line, which is essentially free other on the 0 ROOO precision connector. from aging effects. It is used to measure The OR874 line, while not so accurate Vb\\'R, reflection coefficients, trnnsmis as the precision type, is satisfactory sion coefficients, impedance, and ad for most cveryday measurements, and mittance (resistance, ind uetnllce, and thousands a rc now in use throughout capacitance) of both passive and active the world. It is particularly well suited networks (diodes, tubes, transistors); to the student. laboratory, where its electrical length of two-ports; phase modest price is a boon to the budget. delay; insertion loss or attenuation of The OR87.. Slotted Line has recently networks, cables for example; and die been redesigned to reduce the residual lectric constants of materials. It can \'SWR, to increase the high.frequency range, and to impro .... e tbe constancy of 'R.II. s.ble. L. J. SmiU.. "Studletol Cold-T ... PNc:e. dUrM U-' III th, l)e.. ~loprIIetlt 01 the 1.-40111 c...... t probe coupling. The model number has ",.ad AmoWl ..," BTL Inter1llo1 Reporl. No :<'1 ~1-43-2S43-7. p R; BeUTelep!toae L-abon,wri ... Lau",ldale. Pe. been changed to Typt; 874-LBB. Over
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IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the[;jExpe rimenter
John Zanv received his Yi"- UIIY line, OR900, and Amphcnol B.S. in l>hysica from 7-mm Precision Connectors. George Washmgton Uni versity in 19'18 and his Performance M.S. from Tufts College in 1950. Io'rom 1950 to The VSWR of the line has been re 1900 he WIUI engaged in duced. The \'SWR specification (Figure the design and develop mentof radar, antennas, 1) applies with either end of the line as and microwave devices the source end. A series of representa at Trans-Sonics, Hughes Aircraft, Avco, and Ray tive residual VSWR'S of t he line equip theon. He is a member ped with adaptors pto other opular con of IEEE, Sigma Xi, Sigma Pi Sigma, and a member of the nectors is shown in Figures 2, 3, and 4. Precision Connector Subcommittee of IEEE The frequency range, formerly cover and Committee JS-9 of JEDEC. He joined the Development Engineering Staff at OR ing up to 5 GHz, now ex tends to 8.5 in 1963 and is Section Leader in the Micro OHz. The low-frequency limit is not wave Group. fixed at 300 :'11Hz ; it can be extended downward, typically to 150 :'11Hz, by the past several years many mechanical the use of air lines and the appropriate improvements have also been incor probe tuner. porated, and, recently, an externally adjustable probe tuner has been offered Recommended Accessories as an accessory. The improved locking A convenient power source for slot connector, TYPE 874-BBL, is used at ted-line measurements is one of the OR both ends of the slotted line. Unit oscillators, which are available in These improvements result in an several models and offer a wide choic extremely versatile instrument with of frequency range and power supply. more than adequate performance for a The detector can be a conventional general-purpose line. This line can be slanding-\l'a\'e indicator or one of the converted to use any of the popular UG GR TYPE DXT Heterodyne Detectors. connectors in a matter of seconds, Probe tuning ca n be accomplished through a TYPE 874-Q low-\"swR adap with the T\'Pt! 9(X)..DP Probe Tuner or, tor. These adaptors are available, both if the convenience of external probe plug and jack typE'S, for Types B~C, C, depth adjustment is not needed, with a UN , LC, LT, ?o.Iicrodot, N, OS'\I, SC, T:\'C, Typj,; 874-D20L or -D50L Stub.
Ii. complele meo,urlnll auem bly, con,lllInll 0' the 1m_ p.oved ItoHed tin e, a Unit high_freque ncy ooelltotor with pow .. suppl y, and 0 Type ONT Oetedor .
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IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 1.100 I V - - v .~ - f Ig .... I . Typ. '74-lB8 - 'ISWI. • SP£DFlCATlON v ..... l ! .- '--- - -+ > I V """"--.,¥ _ ~ .::.t- ... I .~ , - • • , , -• "(O"tNe.·~ ... •
" .-
,,~ " ...... >r;0 ~"' > - • .M. -:''::: •> • ...... ~. ~ . ~ J.i • ,
i ,- ,. I.a.o .. ~ 1,000 , 0 , • , • • • 1.'.0 , 1.1.0 1.1 .0 "~". m~ : 1.100 ': '.0.0 Fig ",.,. 2, 1 and 4 ...... "' ..11" ....l d ", .1 VSWI . , tho Typo .7.. _l all oqulpp. d wit h '060 ~ .- .. d .. p' .... '0 o the< 0.. .. . 101 c'''"'''o. typ. " lOOOff'.m. k~ ;:~;:::;;:::;::~~2 3 4 :::;~:':;5 & .. .J!
Other useful accessories: the TYPE Last, but. by no mea ns least in im 874-LV :\Iicrometer Vernier, which portance, arc the Tn'E 874-Q Adaptors allows a precise ndjustment of probe mentioned above' With the TYPE carriage position nnd is pa rticularly 874·LBB Slotted Line nnd a complete useful ill the width-
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IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the!;]Expel'i IYle n tel"
SPECIFICATI ON S CI..... acl.'I"I~ Impada .. ~.: 50 n ::0.5%. A .
Cota/og Pric~ Num~' Ducription in USA 0874.9651 fyp' 174.US 5I a".01 lIlI, $395.00 0174·9652 typ. 174.lV Mluam. lar Vlrlll •• 41 .00 0174·951\ fyp' 174. 020l AoI l"lIalol. 51,,10 20.00 0900·9654 f yp. 900.0' P.ab. r...... 75.00
IMPEDANCE·MA TCHING TUNERS FOR PRECISION COAXIAL.MEASURINc.... SYSTEMS
The TrPE 900-TUB Tuner, for the 3. Stahility - when fl residual stand· 0.25- to 2.a-GlIz frequency range, ing-wave ratio is tuned out, it. stays complements the previously nnnounced tuned out; if the setting is changed, the T'rPE 900-Tl:A Tuner!, which covers original tuning is duplicated when the the 1- to S.5-C Hz frequency range. original setting is restored; if the can· The t.wo tuners arc similar in design and nection between line and tuner is construction nnd, in addition to their broken Bnd then restored, the tuning is wide bandwidths, have the following unchanged. desirable features: Each tuner has three t.uning screws. I. A unique neutral PQsitiol1, from III operation, two of the three screws which rapid convergence to match can arc adjusted for match (which two always be achieved depends on the frequency), while the 2. A fineness of control, so that unused screw is set to the neutral posi VSWR'S as low as 1.0002 can be tuned '·'Cou>.l Than with NeUl ..1 Settiq." 0-01 /la4,. out with ease Ez".nftntln, J .... uuy 1G65..
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IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 Augu s t '966 • ~ Fig..... 1. VSWR • ... ahhl", to"" of .. ~... , ~-, ....TOoIIIG ."", -- IIUG[ the Typn toO.TUB • to" ,oo-ru.o TVI'OeA\. , and . TUA T... " . ... • Sp. clflulla"" and n,( looTJ. n'lCAI. L dolo .haw" a . . ... ". ;;/"+ d • • Ih . ... 011 , u l,I~ · ~X II .... pha .. ~o"dUlo", / _,. ~L. I- 01 the ..11 1< 110 " 10 ~ Yf'l ~ rua .. m( _. rU"'~~~1OfI b ...... " hld awl. "C'" ., ~ •• " • •• • To '" tion. Each screw hn.'i a scale, with tion, or it may be a section of precision vernier, and can be locked at any air line. The tuner is used, thcrefore, setting. to match the imJ>Cdance of the device The VSWR matching runges of the in question to that of the standard. TYI'ES OOO-TUB and -TUA Tuners (see Figure I), while they nrc high enough The Measuring Instrument os an Impe dance fo r most. applications, have beell kept Standard suAlciently low that extremely fi ne The Tn.: 900-LB Precision Slotted matches call be achieved with ease and Line is an excellent impedance stand speed. ard. It covers the 0.3- W S.5-GHz frequency range, nnd, at 2 CHz, for APPLICATION S example, the residual impedance error Matching 10 a Siandard o f Impedance (expressed in VSWR) is less than 1.003. With tbe CROOO Tuners one cao If a composite termination consisting reduce t he residual reflections in tro of a TYPE: 000-\\'50 Standard Termina duced into a cOl1:dal system by termina tion and a TYI'E OOO-TUA or -T UB tions, measuring instrumcnts (such as Tuner is a embled, as shown in figure slotted lines, rf bridges and directional t2, nnd he tuner is ndjuste<\so that the couplers), adaptors bet-ween li ne sizes, amplitude of the stunding.wave pntt-ern and connectors. Thcse residual reflcc observed on the slottc<1 line is reduced tions must always be considered with to zero, then the residual \'SWR of tbe respect to some standard of impedance. composite termination is made equal to The standard may be part of a meas the residual VSWIl of the slotted line. uring instrument, it may be a termina- The improvement in n~wn can be as
FI, ... .. 2. Co",polill , • ...,Inollo" CO",llIln, 01 a Typ. 'X)O·Tua Tw" 1<" and a Typ. 900. WSO TI.... I. nolian, a"ach. d 10 a .... a ' ... o"'I"'tr... ",. nl .
. ,.,.
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IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the[;jExperi mellter
air lines at 2 G Hz is less than 1.0009. Both a composite measuring inslrument "" and a composite termination, as shown in Figu re 4, can be independently and Flgu", 3. Sto"dclrd I • • ml"ollo" otloch.d 10 ° co .... - simultaneously matched to the char pO IIi. m.olu.lnglnllrum."I. actcrlStlC impedance of the air-line st..'lndard , at frequencies where tbe air much as (h'c-fold over the direct. resid line length is nn odd multiple of Cl. ual VSWII of the termination nlone. quarter wavelcnglh1 . The ma tching is Termination 05 an Impedar"ICe Standard aceomplished by nlternate a.djustment of the tuners, I and II , until no reflec A well-matched termination. such us tion is observed by the measuring the T"I'f; OOO-WOO Standard Termina instrument. (I) when the composite tion or, evclI bet.ter, the composite termination is co nl1 ected through the termination described above. can also nir-line stnnuard to the composite be used us an impedance standard. For measuring inslrumt:'nt lind (2) when Lhe e)(umpic, if the measu ring instrumen t. composite termillltliOIl is counected is a direction al coupler or a hybrid junc directly to the composite measu ring tion, the instrumen t. resid ua l mny be instrumen t (that is, with the air line out much gr('at('r than that of nD available of the system). standard termination. III these cases a composite measuring instrument, con Simplifying Substitution Measurements sisting of the basic measuring instru ment. and a TYI'E OOO- TL:,'\ or -TUB Substitutioll techniques, such as Tuncr, ('Ull be fo rmed , as shown ill those described by Sanderson' and Figurc :3, and the tuner adjusted so that Zoo:y·, nre used to oblain nccurate a null is observed with the mensu ring metlllu rcments of sma ll reflections ill the instrument. The residual " S\\"II of the presence of comparable residual reflec- co mposite instrument is thus made equal to that of the standa rd termina • 1'olallK... .li ~. ~ .::.. "8orn~ T«hni'lueo ,,"d Thn, l.i...uuuio"" .. Jl.el,uecl to Ihe M...,UMlmu!.t 01 Sn.all tion. Relleetio"" ill I'1"ffiIoIo1I Couial T ...... ~ Lin"," rr-led "I Ihe 101M! Collf~""Me on ",.".,isioo" .:If,eIfO' ~ ~(_",menla, JUII. 21-24. NBS. IloI>ldet, Air line as on Impedance Standard CoIOredo.. (Pu ...... tiot! IK'bedulC!'d lll\he INKS T ...... GC_ 'i,...... , 1"'",-'\1,,11... OK .V ...... w_al. I>«e",ber The most nccu rate impedance stn.nd · &"'te...., ... A. .::'," " New IH.h-Pncialoll 1'olcthod 1m Ihe M ..... ,..,meO I 01 Ihe \ 'S\\' II 01 Cou..i.&I ConDteW.. . " ard is thc (, hnractcristic impcdall('(! of n. INK T","tc><1 iu. Qn oIIia.J<'CIN T~'.'1t "Old T"'AII>q~., Vol MTT_!l, No 6, Novembfcr, 1001, r> 62 ' ~:!8. section of prt'l'ision nir-d ielectrir (,O!lxinl 'Zony. J .... Prot'oe hnpe.. t J\ " e~ 1'o l eNu,emtnt. "ilh l,ml'h.... i. 00 CanneelOr VijWlt MOAIu ",menc-," 18th line, such a!l a Tlr~; OOO-LZ Hererence Alldull IS .... C"..o nle",nOf' ,,"II £1bibil, Chie"l". I' reprint Nil H .4.63, 1063. (Anollable N O,ne.. 1 Ited;.. lIepriM Air Line. The residual v<;wn of these NCl820.)
" USUIIIItG "[1[1t(0ICl tuN(lit \I t[III""U.TI()IrI ,"ST~T
~---l- ---~
flgu •• • • Sllup 10' molchl"g co .... po.lI..... o.u,lng 1.. It.um. n l ond compoille I • • ml_ "ollon 1o Ih. cho,od"llllc I.... p. don .. 01 "n D; •• lIne . Iondo.d.
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IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 ,-tions in the measuring systems. In these ..echniques, two measurements are re quired, and the desired quantity is dependcnt on the vector difference of "".01 the two measured quantities. When an impedance-matching tuner is used to make one of the measured reflection coefficients equal to zero, the second measurement alone provides the answer!·. This means that it is not necessary for one to perform the vector subtraction or to plot measurements on a Smith Chart and to make tedious constructions. Also. if only the magni tude of the answer is required, it can be obtained directly from just one magni Fle w•• 6. Smith Ch .... ( .. " ...... ' 1.. " , .. d. ' .'m ln, r .. tude measurement. system, as illustrated in Figure 5. (It is Quarter-Wavelength Sub$litutiao 10 assumed that tbe reference air line is Measure Terminatian refleetionlcss and losslcss and that the The simplification resulting from the reflection coefficients of int.erest are --use of the tuner is illustrated by lhe small.) Tbus example of the substitution technique r. ~r. +r. (.) that employs a quarter-wavelength r, ~ r. + r, .-•. - r. - r, (2) reference air line to determine the re wbere flection of a termination in the prescnce r. is lhe measured reflection coefficient of the reaidual reflection of the measur without the reference air line inserted, ing instrument. r, is the measured reRection coeffi Without the tuner, two measure cient with the reference ai r Line inserted, ments are required, one with and one r ~ is the reflection coefficient of the without the reference air line in the termination, and r ... is the residual reflection coeffi cient of the measuring instrument. The termination reflection coefficient is given from the difference of equa tions (1 ) and (2) by the vector relation r. ~ r. - r. (3) 2 Tbe reflection coefficients rl and rt are plotted on the mith Chart of ft1U11M&TIOOo Figure 6 wi.th the construction required to obtain r l' Kow, with the tuner forming a com fie"". 5 . ..J h'w p , .. m ...... r\. b) h l ... p , .. posite mcaauring instrument a8 shown m ... ' ..' . r .. 9
IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the[;JExpel'irne nte t.
"EA$I.III I~ I , r====-l , I I • I ~5rltU"EHl ~ r[RJotIHAr IO ~ fllll,l., 7. "J Set"p 10 odl.", rl 1----.. [ .... $U~:"?:~~Ufo,IEHr-I 10 1 • • 0 . b J S" "p 10 m, O' .,,, r, o .. d '0 d, t ••ml ... r, dl"dly. rUN£R AErEREHCE b 1,111 LIHE
ill Figure 7, r, can be tuned to zero. Xo vector subtraction, and therefore r, - r~ + r, ~ 0 (4) no constructions on the Smith Chart, where r'm is the residual reflection is required. coefficient of the composite measuring Similllr si mplifications can be rea lized instrument undcr the condition of (-I). in other substitution techniques With through the applicntion of the TYPES r7 = r~ - rl' (5) 9OO-TUA and -TUB Tuners. the termination reflection coefficient - T. E. MACJ(ENZU: is given directly by Nol., A brie-f biography of T homaB E:. i\lae r, KenJde, author of the foregoing article, ap (6) peared in the :\lay 1900 i88ue of the El:peri 2 nuntt:r. - Editor SPECIFICAT ION S 900_ TU8 f .... ., . .. ey RO"II ' I to 8.5 GHt 0.25 to 2.5 G Hz Chorod' rl,llc ''''p. do .. " 50n 500 VSWR Molehl"l1 RO"II ' 1.00 + 0.012/0". 1.00 + 0.05/0111 to I GHz (wor.'_co., ml .. lm "m)· 1.05 from I to 2.5 GHz VSWR Ru,nololli.y < l.0005 + 0.()003 fO il. < 1.()()()5 + 0.0003/011 • R,tld"o' VSWR (011 u .... ol. • Rance;1 ""de, ullder ,.. on fOnditio", TE wMODE RESONANCES IN PRECISION COAXIAL CONNECTORS I t has been common practice to been recognized that this mode can specify the upper frequency limit of·a propagate in dielectric support beads precision c:oQxiai system as the calcu below this frequency, but the interac lated frequency at which the next. higher tion between the TEl\'! and TEll modes mode above the TEM mode (TEll) is insignificant if the effective electrical could propagate in the air-dielectric length of the bead is so short that a section of the line. I t has, of course, TEn-mode resonance does not occur 10 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 _ However, the effective electrical length f the bead for the TEll mode is in· Very sharp higher·order.mode creased by the reactive loads presented resonances can exist in dielectric to the TEll mode at each end of the beads in coaxial lines. These reso· na nces can be excited by a sym· bead by the air·diclectric line sections, metry in the line but are often which are below cutoff fo r this mode, so small in magnitude that they are and the resonant frequency may there. overlooked. Recently a resonance of fore oecur at a lower frequency than this type was observed in Typ e wou ld be predicted by simple theory. 900·BT Connectors at 8.70 G Hz, In a coaxial system, either n single its presence was confirmed by 0 thorOlJgh experimental investiga. bead or a pair of beads that are sepa tion, and its existence was ex· rnted by a short section of air·filled line plained by the analysis desc ribed can resonate. The TEwmode resonance in th is article. Since the resonance can then cause an increase in both causes on increase in both VSWR vswu and insertion loss ; if the beads and insertion lo u exceeding specifi. cations, we have lowered the upper are part of connectors, these increascs frequency specification for Type can vary in I111lgnitude as the relative 900·BT Connectors to 8.5 GHz. con nector orientation is changed. The cffect of the resonance is noticeable over onLy a narrow frequency band. line. The condition for resonance of a The TEll mode may be initiated by single bead (Figure In) is that Z, - Z;, ...... &symmetries stich as glota or probes. where Z; is thc (.'onjugate of Zt. The s in a slotted linc, or by eccentricities input im,>eda llce, Z\, to the air·dielec· or irregularities that may occur in tran· tric line is givell by silions between lines of different sizes. Calculations of resonant frequency z\ _ Z. ZL + Z. tanh 11 can be made on an impedance basis Z. + ZL t..'lnh -yl (I) through thc uSC of conventional tron& where mission· line equations. Best agreement Z.= chaf8(.'wristic impedallce of between calcu lated und measured data air--dielectric linc is obtained, in the particular case ZL= terminating impedance of alr- investigated, when the short undercut dielectric line Icngths,' stich as 1·2 (see Figure I), ,,'T~_=~":C<>d ·~ .. 00",_1<1 fot !.he d '1IOOnunllhy inltOdllC*! b,. 1M .t.rupt duo.a_ in u.. oondllc\.Or are treated as sections of air-dielectric d'..... e\en a t lbe bMcl • S!HGU ••0 "."'•. I. c.on.I • • tlonl of GR900 dll l .., .I. luppo,1 budl. II IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 -y = propagation constant of air If we trent region 1- 2 as a section of filled line air-dielectric line and let Z2 = ZI, th l = length of air-filled line. Z, can be calculated from For TEl! mode: , r. Z! + Z.,. tanh n 4 Z. = Z... (6) Z.,. + Z2 tanh 'Yb I. Z. - ;'.;' 1 < I. (2) I ~ 1_ I(f)' 10' where I. = length of bead. One method of solving for I is to where nssume a mlue of I, solve for Z. ( =Z2) I~ = I'utoff frequency for TEu mode in equation (2), Z" in equntion (4) in air-dielectric line and 'Y. in equation (5), and then fin d 1/ = :mi.7. Z, from equation (6). At resonant fre And quency, Z, = Z:·. The resonant frequcncy of the bead ,_2' ,/1_(1)' (3) >. I. pair (Figure Ib) may be ca lculated in a similar manncr. Two resonant fre whNe ~~ = cutoff wavelength for the quencies exist, one below and one mode in the line. abo,'c thc resonant frequency of a simi I n most practical cases. the air-dielec lar single bead. Determine ZI from tric section of line i<; long enough so equations (I) and (2), Z3 from cqua· 0.99 S 1.00. that < t.. \nh -yl Theil lion (6), and Z~ from equation (1), ZL + Z. using Zs for Zr. and calculating 'Y from ZI = Z. Z; + Z~ = Z •. Thus the equa tion (3). Thc short undercu t gions nre again treated as part of t~ input impedance, ZI. i'l an inductive air line ..\t the resonant frequencies, reactance below the ('utoff frequrncy of Zt = Zs·. The two resonant frequen~ the air-dielectric line and is given by cics can be found by successive trials. equation (2) . The charncleristi(' im Calculations on this basis were mn.de pedance and propagation con<;tnnt in for ihe GROOO connector. This co n ~ the bend arC' given by nector uscs a Teflonl support bend, in wbich the TEw mode cutoff fre , " (4 ) Z. - / ( 10' 1 > I. quency U is 7.03 GHz. The cutoff . "I - ;)' frequency in the adjacent air-dielectric line is 9.'19 GHz. The bend is much _ ff_•• ), shorter than a half wavelength (which nnd -y. = j k \ 11 \J (.;) I might be expected to be the resonant where length) for the TEn mode, even at !) GHz, but the loading effect of tbe k = 2w v'!. , reactive impedance of the air-dielectric lines for this mode causes tbe reso- 376.7 11, = -.;;;- t D>lP(mt ItTodemo..k I. = cutoff frequency for TEll mode , J. Dimitri.,.... E.....,t Cutoff FrortueDda of PrecitioQ C ...... '(' ... oW .. ~.... JUlio. 1005. l .! in dielectric bead • N. M ..~uvh., W... IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 August 1 966 nance of a single bead at 8.80 Gllz. howe\'er, the m('chanical stability and Typica ll y. the VSWH in creases by 0.10 ruggedness would be impaired if the at this frequency, and the inc:;ertioll loss bead length were shortened by almost by 0.35 dB. A pair of be:l.ds sps{'ed as 1/ 3, the amount necesS.'lry to raisc the in a Type 900-HT Conllettor pair ex· resonant frequellcy of the connector hibits a resonance at 8.70 Gll z, as pair by 300 i\ llI z. In most applications, well as olle above 9 Ollz. Typically, the resonance of the connector pair the vswn increases by 0.03 at this will go unnoticed. It e>;cllped detection frequency, and the inscrtion l o~s by in the original de\'('lopment work on 0.25 dB. The bandwidth OVN which the connector, {'\'en in swept-frcquency cither resona nce is noticeable is ap. measurements on connector pairs, be proximately 60 ~llTz. The calculated cau'OC its effect on \'swu was both small resonant frequencies agreed with those and dependent "1>O1l ori!'ntation. measured within I %. The higher reso One should {'xercise caution when nant frequen cy of the bead pair was working Ilellf the Ulmer frequency limit not investigated experimentally. of any coaxial system ..\ slIddcn, shnrp While such ca lcu lations arc not com· in crease in vs\\'Jt or variation in vsw\t pletely rigorous (for example, the ef as rela ti vc COllllcctor orienta tion is fect of the steps in innCf zlnd outer varied may indicate the presence of a conductors are ignoroo), t1H'Y do give TE,,· mod(' rt'son.'lllcc. L'nlislial condi u"eful results for this and other bead tions, such as th!' pr<'''!'nce of non sizes. A field analysis was al:«o used to symmetrical d!'\'ict'''1 or of l.'lrge amounts pred ict the resonant frequcllcit' ... but of dielectric clo! - II you would Ilk, 0 .opy 'f OUr " .. nlly pubH,h,d Pri""r 0' Noi,. M''''Uf •• "" "', Iu.t drop UI s Un •• Thlo lilll. bookl, ! dluu .... wllh a light tou.h th. nalu •• and ",. aluf.",. n! of a.aulli. nal ... fr ••. • 13 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the[;lExperimente t. NEW DECADE CAPACITOR- WIDE RANGE, HIGH RESOLUTION The engineer who has occasion to use box make it useful in both laboratory variable capacitors over a considcrable and test shop. Owing to its fine adjust frequency range will welcome the new ability of capacitance, it is a convcnient TYPE 1412-BC Decade Capacitor. It va riable ca pacitor to use with the Type has four polystyrcne-diclectrie decades, 160ik\ Impedance Comparator. covering a range of J. J II micro farads, us well as a continuously varia Construction ble air capacitor, permitting very fine Ceramic-insulated switches, with capacitance adjustment. In experI solid-silver-alloy contacts, select paral menta l circuits, it CUll be used not only lel combinations of capacitors having at low frequencies where circuit ca pac values in the ratio of I :2:2:5. The itances arc large but also, by virtue capacitors are of extended fo il construc~ of its air capacitor and low internal tion for minimum inductance and low inductance, at the lower radio fre series resisbmce. Polystyrene dielectric quencies. is used for stnbility of capacitance, low The wide capacitance ranga e nd high dielectric losses, and high insulation resolution of this decade capacitance rt'sist!l.nce. , , , The capacitors arc housed in a double shield, consisting of an inner box and the out&icie case, SO that the difference between the ca p!l.citances for two terminal and threc~terminal con nee· tiolls is vcry smull- only one pico· INN[~ "L___ -' farad, the capacitance (C NQ) of the ~-, hinding post 1/ to the case. It is partic ularly desirable that lhis ca pacitance flgu •• 2. TI,. oIoubl •• hi . loIing u .. 01 In th. Typ. be as small as possible whcll the capnc 1412_8C D.ceol. Copo 14 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 Augu st 1966 fl ..... 3. terminals are brought out. at the rear for convenient connection (Figure 4). ..__ _-/ ~7.= Readoyt , ,. ~ Tbe four decades bave clea r, easy to-read dials with numbered steps from .~. o to X (X - 10). The air-capacitor f'./ow' Two. ' ..mln,,1 :::... ,...., , dial has ten 100pF divisions, plus addi ( ••oun ..... ) •• nn •• Uon -- ....101, ° Typ. 114.09 tional readout to I pF per graduation . A .. opl"" (A ...... ' Th .... ' ... To read the dial, simply add the number mln ..1 ( 00101 ••, 1,,01 ... lIh .",h .hl.let. of graduations (counting from 0) on ."nn. ct.d 10 th. the fixed vernier scale to the correspond co ••• ing numbered division on the dial. For an increase in capacita nce, the knob turns clockwise and the small gradua tions read clockwise. Sample settings are illustrated in Figure 5. ~~~ -.- • ' 1 .*.'X,1 1>l .... » .. fl ...... S. - til,' 00" EEl Dissi pation factor (A ...... ) Typ. 214_NIC The dissipation factor of the poly 5hl...... Oo ... bl. P, ...... d ' or 1"'''. ' Mmln,,1 styrene dielectric is quite low and rela- (flo"Un. ,.0 ... 01" ) con tively constant over the frequency n.ctlon .01 Typ. 1412· 8C. (t.M T... o_l ..m ln,,1 range ordinaril y encountered in most (•• 0"01 ... ..) ..nn . dl"n applications. At the extremes of the .... 1...... wi•• • capacitance range, minor increases can Figure 2 shows the arrangement. of be expected. the shields, and Figure 3 typical meth At the lower ca pacitance settings, the ode of connection to the panel termi dissipation factor is increased by losses nals. Hardware is supplied for installing in the switch insulation nnd other mate the assem bly in a standard rack, and rials outside the capacitors. The cffect of thcse losses incrcases as the fre quency is lowcred. At higher capacitance scttings, the dissipation fa ctor is increased by tbe series resistance of the wiring. This effect increases with frequency. fig ...... R,,,, po .. ,' Capacitance .. I .... of Typ. 1412. 8C, Iho ... ln. I .. ml_ Capacitance changes with changcs in 0101. for •• or ( "nn'e_ lI.nt. frequency are principally a fun ction 15 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the [;lExperi Inen Ie ,· (f.), the approximate increase in effec :;iii;::fii~~l hisRobert B.S. w in. OCT E.E. received h·om tive capacitance ( ~C) over the zero-fre l Texas A lind 1\1 in 1928. quency capacitance (C.) is given by the Afte r ~wo years as a student engineer at Gen- expression: eral Eleetric Company, he held en&neering and administmuve posta oC ~ fl )'. ill the field of capllcit(lr Co \]. en~neering wi th RCA; Ene Resistor Corp; Typical values of the resonan t fre A:"IIP, Inc.; alld Aerovox quency are: Corp. He joined O R's Development Engineer ing Department in 196-1. He ill chainnllll of ASTM Committee 0-9 on Electrical Insu Dtcode. R ~W/l.On l Frequency lating :"I faterinls, a member of Committee D-27 Oil ElectriCflI Insulating Liquids nnd Capacitan« Front Ttrminal& Rear Terminal& Otll;C!l, a member of lhe i\"RC Conference on l.l111S;.F l30 kHz 310kHz E I ~trical Insulation, and a member of IEEE. 1.0 ;.F lAO kHz 320 ~Hz 0.1 ;.F 1.2.5 MHz 1.2 MHz 0.0 1 ;.F 3.5 MHz 4.3 MHz of the dielectric material below J kHz 10SO pF 10 MHz 17 MH1 and a function of the amount of series ISO pF 27 MHz 70 MH1 inductance above I kHz. Polystyrene dielectric ensures negligi ble variations At frequencies up to 30 kHz, the of capacitance below I kHz, and ex effective capacitance at any setting tended foil construction keeps the in wi ll be less than I % higher than the ductance of the capacitor it-self low. va lue of capacitance at I klIz. At most i\ lost of the inductance is in the settings, the error will be much smaller. wiring. When the operating frequency (I) is well below the resonant freq uency - R. \Y. ORR SPEC I F I CATI ONS Capocltonc.: &I pF to \.1111 5 ;.F ill eteps of Dlntpatlan Fo.lor: 1&1 to 1000 pF, 0.001 100 pF with Il 0- to 1000p F variable ,li r CIlpaci· max, Ilt 1 k Hz; o\"C r 1000 pF, 0.0002, max, at tor providing oontiDUOUS ad/·ustment with ( kHz. l_pF divisions. Capacitance or 2. and 3- In sulation R• • I'Ianc.: lOti ohms, minimUm, terminal connectiona differs by about I pF. at 500 V, dc. OI I II .I.le: l'olysttTene for decade steps. Moxlm .. m Valtog" 500 V peak up to 35 kHz. A.(u .....,.: ±(1.0 16 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 A lO-pF REFERENCE STANDARD CAPACITOR which, after evacuation, is filled wilh dry nitrogen under a pressure slightly above atmospheric and sealed . The con tainer is mounted on an aluminum panel and protected by an outer alumi To supplement the highly stable num case. Each icapacitor s subjected T YPE 1404-A (1000 pF) and T Y I >~; to n series of temperature cycles to 140-I-B (100 pF) Reference Standard determine hysteresis and temperature Ca pacitors!, we now have available a coefficients and to stabilize the capac 100pF model , the TYPJ; 1404-C. itance. Standard capacitors in the 1404 series Two locking GR874 coaxial connec arc highly stable units, hermetica ll y tors arc used 3.S terminals. The out-cr scaled in an inert ga!l, and closely shell of one is connected to the case, djustcd to their nominal va lues. but the outer shell of the other is left All cri tical parts of the plate assembly unconnected to permit the capacitor arc made of lnvat for stability and low to be used with an external resistor as a temperature coefficient. After heat cy dissipation-factor standard. cling and adjustment, the assembly is ' Job F. Henoh, "A lIi",I, s .... bIe ReI ....". Su...... d mounted in a beavy brass container, C.po.c,_:· 0 ...... 1 Rild .. Elpon_ .. ln. A u~un 10G3. SPECIFICATIONS Collb,oU,, ", A certificate or calibration i~ IlUp plied "'ith each capacitor, giving the meaaure 17 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the /;] Expe ri Incnle l' M .."lmum Vollo!!o, 750 V. Acee.. o,ln R' q ul,od, For connection to TYPJ; '-,mlnal., Two lo('king G R8i' I <'OaJ(iaJ ('on lOla-A Capacitance Bridge, 2 TnE 8H-R20_ neclOn; eaeily convertible 1.0 other t\'petI of or Tnt: Sil-R22LA Patch Cords. connectol'll by att.nchmcnt of locking IIdaptol'll. Olr",nllon., Width G~{, height G;i, depth 8 in Outer shell of one con nector is ungrounded to ( 1i5, 1i'0, 205 mm ) over-all. permit capacitor to be used with external Ne' We'gh.: 8'i Jb (a.!) kg). re!liator 8.11 a dissipation.factor standard. SlIlpplng Weigl!!, H Jb (6.5 kg). Cotaloo Number Dnaiplion ,",04-9701 Ty p. 140 4. A Refo, o nco Stando,d Capacitor, 1000 pF ,",04_9702 Typ. ,",04_8 R. fo, e nco Standard Capa cita" 100 pF 1404_9703 Typo 1404_C Rof .. enco Standard Capacllo" 10 pf u.s. Potc.", "umber 2,M8,4~7. INCREASED FREQUENCY RESOLUTION FOR WAVE ANALYZER RECORDINGS OF VIBRATI ON, ACOUSTI C, AND ELECTRICAL SIGNALS The TYPE I9Q().. A Wave Analyzer! is widely used for low-frequency spectrum analysis, because it has three band widths, 3, 10, and 50 lIz, and an SO-d B dynamic range for recording. The 3-Hz bandwidth is particularly popular, be cause of its excellent resolution. In order to take full advantage of that resolution, we are now making a\'ailable a. link unit that will permit record ing with an expanded frequency scale on the TYPE 1521-B Graphic Level Re corder. This TYPE H}()Q-P3 Link Uni t is shown in Figure I instaUed on the wave analyzer and recorder. With this new link unit the fre quency scale of a recording is spread out to 2 inches for 100 Hz, so that a flguro I. Typ. 1900.'3 l in" Unlllnll .. llod Oil til . frequency difference of 1 Hz can be w a uo a,,0IY1" and g,apllie lo uel ' ....' d ... noticed. An additional frequency scale The same chart paper, T n ·t; 1:'i21-9464, of 2 inches for 1000 liz, identical with is used for ooth speeds. that. of the TYPE 1900- 1>1 Link L'nit, The recording reproduced in Figure 2 is also provided. A neutral position shows evidence of the smoothness of the simplirie'!l the setting of the frcquen cy frequency-control drive with this link control to the desir('d starling point. unit. The components displayed a re spaced JO Hz apart in the vicinit.y of 50,000 Hz, and the absence of signifiean jitter in this e.xpanded display demOIl_ 18 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 Aug ... * t 1eee strates that the new drive can be used Arnold P. G. Petel"lOn to advantage over the full frequency f'f!Q!ived hi8 B. Eng d~ range of the wave analyzer. Of course, groo from the University of Toledo in 193~ and hL8 the applied signal must also be suffi 8.)1. and Se.D. degrees ciently stable that the 3- lI z bandwidth from )I.I.T. in 1937 and 19~1 , respectively. lie can be used. For the pulse signal was a reosearch assist.ant analyzed in J ~ igure 2, the pulse repeti at l\I.I.T. from 1936 to 1940. He came to Gen tion frequency or a TYJ>~: 1217-C Unit eral Radio in 1940 If! II. Pulse Generator was controlled at 10 Development Engineer and iJe<:llme Group Hz by a highly stable, crystal-con Leader of the Audio trolled, time-mark generator 80 that. Group in UJ.l7. He is a Fellow of IEEE and of the AcoustiCAl Society of America, of the ha rmon ics up to and beyond the which he "'1\3 Vioe P/'eiIldenL in 1958-59. 5000th would not. show any appreda lie is Ii member of AA.\S, AAPT, and AGU, and of .several standards committees in the ble jitter. general field of acouniCil. The resolution or the 3-Hz band width and the convenient. display of the analyzed spectrum on the recorder Figures 3, 4, and 5 iIIust.rate the make the system well suited to the detail that can now be obtained in a analysis of certain types of electrical, practical cnse. These recordings are acoustic, and vibration signals, in analyses or the vibration of the papcr cluding ror example, the acoustic noise drive frame of the TYPE 1520-A and vibration produced by such rotat Sampling Recorder. A scan or the ing machinery as gear trains, electrical frequency range or the analyzer in the motors, and turbines. normal drive position shows (Figure 3) ..." fIIU •• 2. Sectlo ... 0' 0 , ••"" ..... ,. .p.d.um I... 'h .... Iel ... lly 01 50,000 H2 of 0 30-,.1 pu'" •• p.ol,d ...... ,. 0.1 I . Th .... pond. d "."".n.,. uol. II " ..d 10 Ihow Ik. In_ dl ... ld"ol compon.nll ...... y 10 HI. flIU .. 3. "'''0,.,111 01 'ko ... Ibro"o" of 0 f,omo koldl"l 0 III ••-bilt dri ..... Th . ' ..q" . "cy ICO" II lulflcl."lIy COm . ptoll.d 10 Iho. ,k. 1''''''01 cho" .... , 0' Iho ,p",,"m. 19 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the[;JExpel"i Il)elllel' fig .... 4. "no''I'"I. 01 'h. 10m' .. lbra,lon ligna' of Fig .... 3. b .. , wllh ,h ...po"d . d , .. _ j q ... .. e'!' 1C01 •• Fig" .. 5. Th .... p .... d. d ft... " .... '1 lcol. II " ..d h ... ,a Ihow 'h •• ompo .. . n,. In ,h. "lel"I''I' of 1350 H~ . that the significant components of components and to determine their vibration are at 120 Hz, and in the actual frequencies_ vicinity of 450 liz, 900 liz, and 1350 Hz A significant amOllnt of random rno- A detailed recording in the vicinity tion in the mechanism being measured of 150 Hz with the expanded scale obscures some of the weaker co m, (Figure 4) shows that the belt-gear. ponents. Tbis effcct is cvcn more im· drive tooth·eontact rate of 4.50 impacts portant at higher frequencies. As shown per second determines the frequcncy of ill Figure S. a few components ill the the dominant romponent, and the gear immediate vicinity of 1350 liz nre belt with its speed of .'j fS introduces II displayed clearly, but the existence of host of components spaced about the many others is obviously probable by main component by multiples of 5 Hz. reason of the spacing of fluctuating The torque pulsations from the 1800- peaks at .'}-I-Iz intervals_ rpm synchronous motor and the 120·lIz This new accessory makes the record magnetically driv('n dbration ill the ing wave llnnlyzer an even more ver motor also influence tbe spectrum satih.' tool than before for thc analysis of The large number of components is stable, complex signals u result of compi(>x interactions of the - An'\OLO r.:n:lIso:> various impacts and forces. ' The 3·Hz bandwidth and the expanded scale 'L. S. Wi.l_ An \n,phuul.. Moou'Minn Theory for GDr_lnduced \·,bralinn.:- Chapt... t7 n' M M' .....",UI make it possible to display these many B,.g;~nri~~ by P. K. Slf!in, Ttmve. AnIOn •. 1002 Co1.alog Numoof D~empllfm "d WI Sh,p WI Pf1ce i1/ USA 1900-9603-1 T'!'p. 1900.'3 l l"k U"i' I Ib (O.S ~gl 4 Ib 0_9 kgl $SUO 20 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 LO CATING SUBMARI NE CABLES Crossing San Francisco Bay are a great many submarine cables, which the Pacific Telephone and Telegraph Company uses for telephone services. An important factor in the 1ll1linte nnnce of these cables is the ability to locate them accurately, nOL only in case of cable failure but also when COII tractors or government agencies are working in the area. Some years ago, the Bay Area Chief Engineer's Department. of Pacific Tele phone developed a magnetic-induction system to locate submarine cables. A high-current oscillator sends an audio fllu" 1. A. Illn .. l h "ppn.d '0 , .. , ~ .. bl.... frequency tone into onc cnd of the ,"o.. n. lI . n ...."nl .. maln. ';C 11 ,ld ..... Ic .. h d . l.d, d b,. .. pr .. b ... nd ••••I .. lnl . qulpm.n' In cable with ground return. Receiving ' ... I .. un .... equipment is installed in a motor launch. The fie ld produced by the level and then in detecting it from tl cable current induces n voltage in a distnnce: coil, which i!l amplified to operate a I. Crosstalk enters working pairs of meter and a loudspeaker. the cable. Recently a new receiver and trans 2. Harmonics interfere with carrier mitter were assembled to replace older systems in the rable. nnd less reliable equipment. It was de :t The receiving equipment picks simble to inCr<'ase the range, which up 6()..Hz fields. formerly was about 50 fcet, and to .... Harmonics of 60 liz interfere package the receiver into one small with the received signal. trnll~is{orized unit. The new system is .j. The sensilive receiver picks up shown in Figures I and 2. noise from working circuits in cables. There are scvernl problems associ· G. C!l.ble cap!l.city shunts the trans· ate II'I:.o.IUI FIIUr' 2 . Elemenl .. ,,. Hh.m .. lic a ll " • ...... I .. lnl equlpm. n" -"• L-__-1....._ l'I"'g Ii2:l! 21 IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 the[;jExperi ITIente l' of 150 Hz produces the best results. If the transmitted power is reasonably NOt E free of distortion nod the receiver This iutere!ting description of the use of sharply tuned to 150 Hz, the above electronic instruments to solve lin important problems are, for a\1 practical pur communications-system problem is published poses, overcome. through the courtesy of the Pacific Telephone and Telegraph Company. Those intere!t.ed in The I.;o....Hz transmitter must supply further details of the apparatus are referred to a considerable nmount of power i.ll an article by L. W. Gunn alld H . .Eo:. Bomar, order to produce a mngnetic field entitled "Submarine Cable Detection," pub li5hed in the Dceember 1!}65 issue of EUdn'cal strong enough to be detected at some COM/ruction ami .lfllintelWlKe. distance. The General Radio TYPE 1308-A Audio Oscillator unu Power Amplifier proved io be idenl for this application. I t. is capable of 200 watts source, a distinct.ive tone is produced _ output nnd has meters to monitor the A small variable capacitor connected output voltage and current. to the oscillator circlJit is driven by Figure I shows how the signal is a 120-rpm clock-type synchronous mo applied to the cable. Scveral conduc tor to shift the frequency ±2 Hz (sec tors of the cable nre conncctcd to Figure 3). getber at both ends, and the conduc The detecting probe consists of a. 5- tors are grounded at the far end. :\Iaxi henry winding on a laminated iron mum resistance is about. 700 ohms. ('on" tUlied to 150 Hz with a shunt The 150-liz power is applied betwccn O.22-pF capacitor. It is mounted verti the multipled condu(:tors lind ground, cally Ilcar the bow and below the deck aod the output current i" adjusted to of the hunch. The probe connects to be between 0 .. ') to 1.5 amperes. the input of a General Radio TYPE To ensure that the received signal 12~2-A Tuned Amplifier and Null De is the /)IH' of inter('st and docs not tector, tUlied to lJO lIz. The output come from n. power cable or somt' otht'r drives a transistorized power amplifier and speaker (see Figure 2). When driven at. 150 Hz, a trumpet. - type speaker was found to produce a (HUN.l "'HOR'IlI!'VE"I t:-----+ U .... Ct"fOfl ~g .. NEtTlO TO ...... • marked third-harmonic output, which esClll. TOR C!RCUIT is easy to hear. As the launch ap C!OI ~ ~; proaches the cable, the operator hears , #'0' . L.- , the tone on the speaker and sees the relative level all the meter. The toile ; <0' L..- a becomes louder until the probe is r-~ ,~ directly over the cable. at which time I ' a null is produced. The meter is used to locate the exact spot. The tone is I heard again as the probe moves past '<-'jI the cable. Flgu •• 3. to p.oduco 0 w",bl. Ion,. " mOlo. To locate a cable break. the Wile is drlvo" c .. pocllo. Is IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 A u g u st 1 966 water grounds the severed cnd of the mullipled to reduce the resistance. To 'able to complete the circuit. inCrC"asc the rangC'. the C'urrent eun be With O.. i ampt're of transmitter cur~ increased and still not exceed the 200 rent and the eablc in 80 to 100 fcet of watts output. During tests \\'ith I.'; water, the receiver gi\'es an excellent ampt'res of transmitter current, the indication about 100 feet away from IUlllleh reech'ed U l'iignnl, somewhat the ('able. If additional conductors of weak, but usable. in over ZOO feet of the cable nre available, they call be water. - <. • • ~[?O~CS· Autotransformers Control Simulation of Solar Radiation on I'IwU> court .... oj a ...... ""' •. ltrttBJI J:ft(linfui,,!/ ('o'l"'!lJlion. lunar Excursion Module R.lA_, L. I .. .\CIO \'0',1" Shown here o,e 12 of 14 boy. in !h e !he'mol·!e.! required, it i. done manuolly with Ih. f'''''''panel conoole de,igned by Grumman Ai.crof! Engineering ~nob. COfPOfO!ioll !O check out a l,lnor Excuro.ion Module Variac outolron.lormen we,e .elecled for !h!. mock-up under ,imulo'ed Ihermol condition. of outer in.lallari"" for .e~eral important ,ealOn•. Fi,,!, 'heir .poce. Eoeh of ' he 252 mOIOf·driven Variac' ou'o· proYen re'lability, ,imple delign, and l000%-oyerload tron.former. accurately conlrol. ,h. yoltage applied capability guo,on!ee d.pendoble opera lion and '0 a r ••i,tiYe healing element affi ..d to tile .kin minimum moiMenonce. Second, 0 Vorioc doe. nol de,lrOY wovelorm p~rllY by (!lopping Of ,e"'aping; of !tie lEM mod·up. A .ingle pu"'bu1ton energl ... if Ihe inplIl Yoltoge I. 0 .ine woye, Ihe O~lpUI voltoge Ihe molOf' 01 all 252 Variac Iran.forme", and th.ir i. a .ine wove. Con.equenlly, no RFI h produced. ""'put yoltoge. 011 ri.e .imultoneou.ly from n,o Third, mOlor·driyen Vo,ioc aulolronsformers can be 10 pre.e, ..... llage. e,tobli"'ed by Ihe needl. poo.ition. progrommed, which eliminole. Ihe need for manual of ommelers tn conjunction with opticol meIer f.lay •. Od(u.'men, 01 Ihe iniliol yolloge opplied 10 ~acll If furthe, fine adju.,m.nl 01 any particular Vorioc I. heoling elemenl. IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988 EXPCI'iITICnter GENERAL RADIO COMPANY wr:O T eo.. C ORO. MASSA C H USr:TTS 0,.,0' ( SOUND CALIBRATION CONSOLE Thlo Sound C.. IiI •• olion Console woo supplied 10 the Colib.otion o .. d Metrolog,. 01..; ...... , Nowo,," Ai. Forc. Stollon, Newo,,", Ohio, lor ..... o. 0 'oborolO<)l .tondo.d 0' ..a>U.!;col colib'otlonl for tho U. S. Ai, force. Among tho ....<11 ...... "1 cop.. bMitie. of llIe conlOI. 0" Ill. following: MI .. ophon. C.. llb ... tlon-Ruip r(}('1 lg ,lfe/hod Ch ..... ct•• I'ti .. 0' "" •• hol. Roo .... o"d Ch ..... b . .. MI .... phon. ColllKolion-Compari«m ,Ilelholl R.v •• b .... tl .. " M ...... "h -Band' of .\'qju OI.. (lla"a' Co llb.olian .. , Mi .. aphonu R...... b .... tl .. " M ...... , ...... t.-lI"a,blt: T()nt:. Fre...... y Rospo .. I0 .. , Mlcraphon .. F...... ,. Rosp""10 .. , "",pU'I ... f ...... ".,. Rosp ...... I T.. p ••" .. ,dor' F...... nc,. "noly.It-SlI1Tow Band Tap. R.. .. ,dinll al SllIna" , ...... cy Ano'y,'r-!oi.DdaN' /land M . a ... , . .... "t a"d "n .. 'y,1s 01 Tap ••• • ca.d.d f ...... n.y " .. aly.I ...... Dda!~ /Jand Sllinali .. I ...... i.i.. are i."it.d Iw oco ... tic_tn.o...... 1tI 'y.I ...... 24 GENERAL RADIO COMPANY WEST CONCORD, MASSACHUSETTS 01781 " -"'. IET LABS, Inc in the GenRad tradition www.ietlabs.com 534 Main Street, Westbury, NY 11590 TEL: (516) 334-5959 • (800) 899-8438 • FAX: (516) 334-5988