z ra r2~ ~PEBIMENTEB ~ VOLUME XX Nos . 6 and 7 NOVEMBER and OECEMBER. 1945

V> z: = ..... AN IMPROVED MEGOHMMETER FOR c.>"" A· C OPERATION ...... eTH EM EGOH M M ETER,since the in • .... l ro

.... 't·, 1...,I.m!"A" OI,,,,,,,~ ... f~ .he ::E"" Me""',", H...... C, 11, 1""_;,.,,,,,. ,.,.., \'<>1. 9 • ...-..... I .~, 5. :;"I,'~ ' nt..,...... o.,.oL.. 1936 . c.>"" FIGunE I. Panel V;I'W of t he T Yl'J'; l/Kil.'\ \Iegol" nmcter. S Uf'cNOt'Jing Ih (-' '!'YI'E '187·A. t h i ~ ne'" i n8tru mc,,( m eMur..... ref!i$ t ane~ from 2000 ;! to 50,000 megohm8 ami Cll n also • be uoed aa II d o(! .

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 GENERAl RADIO EXPERIME N TER 1 elude elimination of tbe zero-se tting a],le for the ra pifl testi ng of condensers knob and rearrangement of the panel so ut p o on l}' a few tl1 ousandth5 of a micro­ that lhe long dimension is frolll LOp to farad in capaci tance. The Tn '~; 544-13 bottolll. T he sw,e of the insln llueut is Mt!gohm _Bridge is recoUlmended for llIlcbangell. leakage testing of bigher valued con­ The lIe\\ low rallge, also incorporated denseI'!!. F or applications not subject to in thc T'I'E 729-A Battery-Operated special requirements of this kind and for \ 'legohrnmet,er,z makes possihle a de­ resistances up to 10,000 megohms, the nection of at least a full division fo r re­ new TYPE 1861·A M egohmmeter wi ll sistances from 2,000 to 50,000 Uc found equally accurate and fa r more megoluns. a range of 25 million to one. rapid and couveu.ienl in usc. The widc range ami the addition of t ll ~ Thc stand ard resistances of OJ, 10, voltmeter scale greatly increase the util · 100, and 1,000 Illcgohms cmployed in ity of the instrument in trouble shool.ing. thc IIlcgollmlllctcr cireuit call be con· The stabilized circuit not only make;> nected across the voltmeter as desired, unnecessary a pre liminary zero adjust­ so lhal the voltmeter resis tance can have ment before !lSI', but also cLi mjnati·;. t he four t'orrespoml ing valucs frolll 1,000 nuc tllat i o n ~ in th~ meter reading resull ­ ohms l)C r up to 10 megohms pe r volt. lu g {rom lille voltage variatiOllS. As II For applicat ions where the voltage drop res ult , accurate measuremen ts in the of 100 volts Clln be tolerated, the instru­ very high ranges of resistallCC can be IflCIJ L ('an also be uscd as a microa lU ­ made very rapidJy and convcn.icully. mcter Inn -iug a maxim um full -scale scn­ The instrWJlcnt is applicable to gen­ ;;i ti \ it.y of 0. 1 microampere. eral high resis tance ami 1t:akage testing The instrument" like its predeccssor, is except \\ here spc('i ried test lUus t suitable fo r many IS I)C cial appl ica tions be applied, o}f whcre the high -vlll ue such as de termination of the moisture standanI rf!15istanc" 15 clllployed in the cO Ul ent of wood. paper, dc hydrated (' ircuil would n'!;u l t i,l all eXI:cssively prolluellS, ami similar m a t.erials. T he large tim(, CO Jl ~ \iln t . The laller li mi ta­ fuldi tional scale makes such determin a­ lion means that the cquipmcnt is suit- tiolls possihle for a wider range or matl!­ rials and for higher moisture contellts. 'w. N. 1'",11... "A I'"",.hlp .\1 ",..,hmm"I..... G. n. £:<,_1- "''''''''. v.,1. I;;. N". 2. J"ly 19.1(1. - \'fl . N. T UTTL E

r: + • ~ • - G:t t " "'" d, In ~ '" MEGOHMS DC 'oIOI..n

r l<:UIIE 2. Elementary IIChematic circuit tiillgrll m of t he l11 egohllllllelcr. The eircuil i ~ e;,nil ar to (hHI of Ibe conventional . LuI II vacuum.llllle ,"olt llIeler is u ~ ed a ~ the indicator.

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 NOVEMBER Jnd DECEMBER, \9.5

S PECIFICATION S

Ran Ie: 2,000 obms to ;'0,000 megohms in five humidity) t he accurncy of the inHmment iOj' overlapr;ng range ~: zero \0 100 voh ~, de. substllntially j"del'""denl "f ternperature und Sea Ie: The standard d irect-reading ohmmeter I,muidity. caliLrnliOIl is IISOO; Ctl nter 5cale valuCi!- are 0. 1, Vollale on Unknown: Th ~ (0 1'1,lieri volt age I. 10, 100. and 1000 megohms. Length of IICale, ,.... the ""kno"·,, d lleol flot e~c ..'t~ 1 106 '· o lt ~ 8",1 3}1 in ches: oen tt"r dt-cade, 1% iucht"ll. The ... ·ale vllri.:.! ... ith the in,liclltion. ill iIIuminuled hy n laml' in the indicllliug mei er. The ,>ollage IICsl.. is li near. Tub es : Th" " ece;,~ "rl' lui,,,. (..... I~ I"· I·v . .... nc tYllIlll5. lind one OC. /VR_1 50 ure SUI 'I'li t~ l . Ace uri e f : Wi lhin ±5'fl, of the ind.icaled value bel ween 30,000 ohms and 3 rncgohmll. and Power Supply : 105 10 t25 (or 2 tO \ .... 250) within 8% hetween 3 me;ohms aud 3000 meS- v.... I18. 10 II) ('0 eycffllt ae. The I'I) ... er required i ~ 01."ll 8 when the e!'ulral decllde of the flCale i ~ 10 walll;. uBetJ. Qutsiue the cenlral decade the er ..... r ;n. Acces sories Supplied : 1\ ~e vell·root con­ ereae~ l~a " l!e of Ihe ctllnl'reftj!ed IICll le. For n ~'C liI\O;; cord. voltage IUcaenrcrncnB Ihe accuracy is ±2 ~:' of rull ll(!n le. Mounti nl: The in ~ lrurn c nt i$ 8uI'Plictl in 8 I np u t 1m pe dine e : leor voltage me86llremenU walnut e llBC and ;15 mounted 00 IIIl engrllved the input iml>cdance in megohms is ind;cntcd hlllck craekle·finish aluminum pan"L by the selector 1I"-;lC" . 01 rD ens Ion 5 : (Wi.!th) 10 x (hcigllt) II x (derth) TemperJture Jnd H umidity Eff ects: 5M iuchel, I)ver_ nll. Over the normal range of room conditions (65° Fahrenheit to 95° l~ "hren heit; 0 to 95"';' relative Net wei ,h t :8J{ IOO u"tlS.

Typ" Code Word Prn. 1861..A I Megohmmcter .. $95.00

AN ANALYZER FOR VIBRAT ION MEASUREMENTS

• MEASUREMENT of thc cffccliv(' 761-A Vibration Meter over an extended amplitude of vibra lion acceleration, frequency range of 2.5 1.0 750 cps (150 veloci ty, or displaCCIIlC I1L wit h a vi bra­ to 45,000 l-pm). Tbe frequency band tion meter and vibration pickup is iu fro m 2.5 to 25 cps, oo\'ered by two some instances adequate fo r complete ranges in the instrument, provides a solu tion of a l'ibrat.ion problem. This is most im l>orlant extension to the spec­ true when the vibration is k.nown to be trum whicb can be analyz('(1. T he major essentially sinusoid al in waveform. co tnl>Ollcnls in a complcx vibration will A complex vwration, on the otber often be found here, and it is seldom baml, involving a number of compo­ Ihat an analysis does uot reveal at least neuts of differing frequcncy nnd ampli ­ one component in this rel:,rion of tbe tude, wbile mcasurable in its overall spcctrum. effect by the vibration meter, call be :Modificd to permit faster analyses bandied completely only if broken down and a wider range of npplication over into its various components by some the sa me frequency range, the instru­ form of nnalp..cr. ment now in proriuction is known as the The TYPE 762 •./\ Vibration Annlyzer' TYI'£' 762-B Vibration Analyzer. Its was dcsi);,'TIe(1 10 ,.ork wi th thc 1'YI-'£ important cbaracteristics and its use i1l ITI'" .n.I,_ w.o d"""'bed , .. ~ A .. Ao . I,. ... r", S"h­ analyzing complex vihralio ll and voltagl" ,bdibl ~ . 'req... aei/ s.;.,. ., " ",.ric.. Vol. XIII. N". ". p p • .,60-36:. waves ari; dc sr. ribcd ill sur·(·ec(lin g para- fo.pril, 194Z.

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 GENERAL RADIO EXPERIMENTER • graphs. The panel arrangement is ShO\\l1 clcarly in this figure. The brol!.d se le("- ill Figure 1. Livity feature is extremel)' hclpful in ~ A! in the sound analyzer, the circuit locat ing coml)Onents quickly in a fast of the vibration analyzer includes a s\\cep over the spectrum, the final linear amplifier with a resistaJl(;e~apaci. determination of fre(juency and ampli . tam:e ·tuned feedback net\\ork, resulting tude being malle with the sharper nd· in high 8electivity Ol'cr the entire fre­ \Iork. queucy range. The seleetil'jty provided As frequenlly OCCUl'S in \·ibnuion is similar to that of a C(l nstant Q. con· work, a component may be drifting bat'k stant impedance.lel'el, resonant circuit and forth or warbling by severall)Crccnt ill the vicinity of tile tunin g peak. ahout a mcan (re1lucllcy, Under slid I 'rwo hand widths, one corresponding conditions the high Q network \\'ould to an effcctive Q of about 50 and the provide unstable or unreliable indica· otber to an effective Q of 10. are avail· tions of amplitnde because of il.8 sharply able wit h panel s \O·itching. Figure 2 peaked characteristic. Here the uroad shows typical select.ivity curves in thrtlc selectivily network finds another illl­ regions of thc spectrum and includes for l)Ortant usc i,n making final determina· comparison similar curves obtainable lion of mean frequency and alllplitud~' with a heterodyne analY7.er such as the of cO IllI)Olu; nts. The nat topped charac· TYPE 736·.A Wave Analyzcr, which is tcr of the broat! se leci ivit y cun'C as ("Olll' designed primarily for elec trical Wl!.ve pared with tbe peaked characteristic of aualysis anti has a constant. band \\idlh the sharp selectivity curve in the imme · in cycles. The advantages of the ('Qn· diate vicinil]' of a luning j:leak is shmln ~ slant, percentage baml widlh of the in Figure 3. degenerative analyze r arc illustraled The \'oltnwtcr of lhe instrumeDt. 11118 an approximately logarithmic scale t'alibrated in lin­ ear ullit.$, @.() "'1' 10 provillc U811blc in_ ,licl!.tions IIf 1'1·111. ti\c amplitude of ("O JIII)(I nenLI! 110" II lOaboutl% oflhc largest componcn t \\ ithoul swilcilin l!;. Twoscalesare fur­ nished 10 mat.d. those on the indi­ cating melcr of the TYI'E 76 L.A Vibration \Ieter.

F1CI,;H& I. 1'"",'I.,;.·w of fhe 'l'l'J'~ i62.n ViLn,t..iOI1 AI1al)"llt"r.

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 5 NOVEMBER Ind OECEMBER, 19~5

'-II an a nalysis to determine the rela­ just outlined - the method of setting tive amplitudes of the components of a the SENSITIVITY cOlltrol of the ana· complex W8\TC (\Tibration 8C(:(' le ra tiOIi . IY1.er. For this adjustment a sinusoidal velocity, or displace ment as detcmlined signal must be applied to the ,·ibration by vibration meie r switching), a pre­ meter and the analper adjusted to give limin ary sweep over the Sr.lt'Cl r Unl i~ the saJlle indication liS that of the meter. matlc to {lillcrllline the comrlOllcnl of This lUay be most simply Iione by II sin g greatest amplitude. With the nnulyzcr the 110.volt, 60-cyelc, signal applied tuned to tll;S component, the SENSI. throngh the power cord 10 the vibration T IVITY control is adjusted to all inrl i. meter as in the Donllal cal ibration of calion o f 100 on the upper (black) scale. this instrument . \1;1 ith the CALIBRA­ This control is left fucil al the above TION-I bullon depreS8ed , the METEn se tting (or the remainder of the analysis READS switch lle t for accelrralion, and and a fma l sweep over the spectrum is the M ETER SCALE swi tch of the vi­ matl e. As caell component. is hUlCd in, bra tion meter adjustell to give an indi­ its amplitude and frequency arc reo cation greater than onc·third of lull corded. Amplitudes are then di rect reml­ scale. tbe SENSITI VITY control of the ing ill percent of the lImplilmlc of the vibration analyzer ill udj ustcd to give 3n largest component. The uppcr (hltld;: ) analyzer indication illent ical vtith tlt at scale is the only analyzer scale used for of the vibration meter. This makes the this lype of analysis. analyzer direct reading: for all compo· A complete analysis of II oo lllpl c..~ nents, in the unit determined by the vibration. wllich yields the IImplitudl's subsequent sKitch se ttings on the vibra· r of the various component.s in terms of tion meter. The SENSITIVITY control t heir normal nnjts (i.e .• illches per second rnus t ~ of course, not be sbifted through­ per second for acceleratioll , mif'roinche8 Ollt succeeding analysc!!, and corre­ IJI'r /!I'collll for vdoci! y, and mieroiudu-... spoll(ling scales arc rea d on both the for displace ment ), lII ay he UHlflt' Ili tlt Rlllllp:cr tt ud meter imlicaling instru­ olll y Ollt' modificlllion of tlte proccllurc men l.".

r , 1 , -~ ""'; FI (~ \.Iu. t . CompariljO)11 or i!el ec li \' it) cunCII of , "~ "l." ' .'Hr ~). 15 • Ihe dcgencr:u;\,c 11",1 •. 1 -I,tH~~· • , helcrndplc u llal p.cr ~ . ~ I'\ .r .. itorillion analysis. ~ ... • ~ ttt-H!t+ItW"1 til .. dC1lcncrativc type ,- i~ prdcuhle IlCCll u;,c 3 • it lo ll' II ro.nllllllll per­ • +-L+'i t'-l'o ~J eenlll!:," band wid lh. 1 ._ 10- ""'_ COWPloI!tSON 01' S[LECT!VITV Ct/flYES OF OEGE ..t"J.T 'Y[ AND TYPIC.&L HETEFIOOlN[ .... J.L"fZ£~S

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 GENERAL RADIO EXPE RI MENTER ,

the \·ibralion 1Ilf'1 f'r is ll sed as a lligh. I.nput.lmpcdauce, high.gain, linear am· plifier (the acce leration characteris tic of thc meter is that of a linear amplifier over approximately t he fre quency nlllge of tbe allulrzer), alit! is inse rted be tween tl ..: bridge antI the all alp.cr. The input impedalll.:c of tbc vibration analyzer va ries (rom 20,000 to 30,000 ohms de· 1 I)t! milllg upon the settillg of the SENSI· T IVITY COli I 1"0 1. Wi th tbe SENSI· •• •• • • -~., 0 - , .J ., ..., .• T I VITY control set at a maxi mum, full OE\1.II.;IOICllti PEIICENl O~ FREQuttiCY AT PEAl( scale indica linn is ohlaincd wi th an input volt age of ahout 0. 1 volt. Under F'I Cll

S PECIFICATIONS

F r e ~ UIn CY Ran 1 e : 2.5 to 750 eyciCii. co,·crco.l ei tl,er range Wi lhi" ± I .110. The ilCnsili vity .)f io fi ve ra.ngCII as follo"'$: 2.5 t o 7.5, 7.5 1025,25 II,,· L ..",d sell'C ti "ily network is the same as to 75, 15 10 250, 250 to 750. t hltl of the aharl' 8flk'Ctivity network to within ±2 ,Ii,. Ban II Wid t h : For the ~harp selecti'·;I), JlO'Si. lioo. the reiOlive attenuation i~ apf"oxullately Vo Iii I e Ri n l e : T he analyzer wi ll gi,·e u~aLl e 30% (3 db) at a fr(!(tueney diITering Iy I % from i,,,Jjllations on input ,'olugea ranging from I that to wbieh the anM1Y7.cr is ,unell. F(>r tho millivolt t o 10 vol lot<. The meter 8fla le iR cali. broad !!Clectivily ,_ itioll , Ihe attenuation ;s hrated for reH tling d,rectly component toile! 30% fOC" a frequency ,I,!Terenee of 5%. At one down to I % of tI.e funda.nental OC" etrongeU octll ve from the 1>Cllk, the relat,ve attenlllltionll OO"'llOncn1. Accordingly, to make full uM: of lire 9R % (3:; db) lind 90% (20 db), respecli,·ely. tbis feature, the inr.ut voltage al tile 6lrongest coml-"?'Ienl or fU ll! a'nelllal should he 0. 1 volt Frlquency Calibratio n : The accuraer of or 'ugher. freqllener calihratioD of the 8hllrp l!elec... vity netw(K"k. 18 ± I ~% or ± 1,J.

  • 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 N OVE M BER and OECEMBER , 1945

    va.. : uum.lube \' 011IJle l ~ cirell il. whiel. 11110"'& voh I,atteriea. or the e<:lu;valeut. A oomlmrt. :I ralllle Ilightl,. in "~ uf 4{l decibels. or 100 mellt a provided in the c .. se of the analy:r.er rOf" ,.-.. to I. to be ...,a,1 Oil the IUcler ""ale. ho ldin ~ ..11 batteries. and oonneclion.! Are autl)' III ll liCIIlly maue to t he " . tterie. wben the oover fill .1. r : The imJicaliog meier is CII III/raled of this comparlmelll if dOllN1. A let"f battee-ies down 10 1% of the fundamental or ~ lr ... ng~ 1 iA included in the I, rice or tbe ineln.ment. component. Accessories Sup p lied : ,\ shi,·Ide<:1 caLle· T .1. P h 0"' $ : A jack is I'ro,·iJed 011 tbe III,nel 1I"" 'l'lu l; u;!f'mhly fur .:o,,,,oot;,,& tbe allalyzu () . ,.luggi nG ill /I I'llir of hea.1 td':I,I,oucll. in to the "ihr:.tiI)U fIIcter. order 10 ·'istcn to I Ie actual 0:':" I1IK",,,"1 of II ... IM,mud 10 which the inst ... ",cut ill hlUed. 'I'l1 i_;8 C a sa : The a""lp;er i~ built iutu II shieldetl ,.1110 lI&etul " 'hen using the analyzer lI8 II I,ridge. "arryi"l; ca;oe of ai fl,l llnc.luggage oon~ tru c ti o ... ltal .. llcc il1dicator. I" addition to the handle"l1 the Cll rryi"g cne, a hllndle iii provitl.. ~1 un the pand or the in ~tn'. Tubu : TliRt: 11I4·G lIud ouo: IF7.GV wild ",ellt for cotl"eniencc;n moving the innm",cnl are required. A lleon regulator tuhe (type ahout while it ill in operation. T4~) u; . 1&0 uSottI. ,\ oomJ.lete lie! of Inl~ iA 11II111)1i~1 with the ;1161",",(:nl. o r men s ion~ : (Length) 18 .. (width) LO}; (beight) 1 t l.i incbea. ,.... ee-·II II . lIall "lls: Th" 1".tlecie8 reo;luifl:'d are (our RurS"h Nt). F2 8P 3'''011 bllilcrit'!l. or the N. t We i lilt : 3 ~ 1)() lIlidii, with J.llttcri Cil: 27 ' , ~~ l'u .... Jenl. ami three BU.gesA No. ZlON 45· I)QUllrU, without hlllt"riea.

    1..:(1 " (mJ " rice>

    762·11 I Vihration Analy:ter . . I , \ 1 .1. 11.1) 8275.110

    MISCELLANY

    • P AP E R S - I I. B. Ricillnoml, Chair. ' I'extile Di\' ision or the American Society mall o f Ihc Board, spoke al. the I'ourcr· of H echanical Engineers in Nc ... York, ellcc 011 " l l1 slnllllenla t;on an(1 Illc No\emhcr 29. Lniver'S;t}'," held at Camegie I ui>l; lule or Tedmolo!,!}' on October 17. Uis sub· eWE HAVE AlW AYS BEEN jecl, "Educational Preparation for an PROUD or the broad distribution of Instrumenta lion Career ;n the Elec · CR products in industry. A good illus­ tronic Induslry." tration bas just come to our attention. On Nou'mlM;r ] 2. E. E. Cross or Ihe I n the October, 19 IS, i..sue of ElocIrOtIi.cS, Engineering De parllll{' ul sl.IOkc :It Ihe l'ic attercd among the adn:rti6C ments and RocheSler Fall J'l leeling on " A Coaxial articles t hcre are {ourlcell pictures or " odifiel\liOIl of Ihe DUlled l y Cireui!." C R e(IU;plUcllt in as mauy different uses. Or. A. P. G. l'elc l."on of tI,c Engi. We Ihank Ihe lISCrs (01' IIJcir confidence, /l eering I)"pnrllllelli spoke at Ihe Cill ' eiJlmtti Section of Ihe 1. R.I':.. Novem· • DON ' T M IS S Ilt(, Gene ral Uadio ber 20, 0 11 " II igh.Fre(IUcncy Measure­ exhibit at the Winter Technical Meetin g ments. " or Ihe LR E .• to be IJe ld at the lIotel f van C. Easton or the Sales Engineer. AMor. Nel\ Y o r k. Junuary 23- 26, 1946. ing Departmcnl dcl;\'crctl a pape r en· Ne... designs will be displayed and - lidell "TI,e II;SlOrr and Tecllllology of General Radio engineen; will be on hand the Stroboscope" at a lOee t;ng of the to ans ... er your ques tions.

    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 GENERAl RADIO EXPERIMENTER B

    EAS TON TO NEW YORK EN GINEERING OFFICE

    gineering staff at Ihe Cambridge office. 'Mr. Easton was bom in 1916 nnd at­ tended the public schools of Rockport, i\-iass8ehusetls. lIe received his B. S. degree ill electrical engineering from Norlheaslem University in 1938 and his M. S. degree from Harvard in 1939. Upon complelion of his graduate work at Harvard, he joined the engineering slaff of Ihe General Radio Compnny and has worked iu both the development cn­ gineering and sales engineering groups. Rea(lers of the Experimel1ter will recall his many articles on bridge eircnits and illliledance measurements. Mr. Easton is a senior member of the I. R. I ~. and for the past two years bas been Program Chairman for: the Bostoll Section. Ue is also a member of the A. 1. E. E., a member of the Society for ~ • E F FEe T I V E alxml December 1, EXlleriOlental Stress Analysis, and com­ I \'an G. Enston becomes mnnagcr of Ihe pany representative of the American Ne" York Engineering and Sales Omee Society for Testing Ahterials. During of Ihe General Radio Company. :Mnrlin the war .Mr. Easton has laught ES.MWT A. Gilman, manager of this office for the eourses in radio engineering at North­ past two yeal'li!, returns to the sales ell- eastern University.

    GENE RAL RADIO COMPAN Y 275 MASSAC HUSETTS AVEN UE CAMBRIDGE 39 MASSACHUSETTS TELEPHO NE: TROWBR I DGE HOO BRANC H EN GINEERING OFF IC ES

    NEW YORl[ 5. NEW YORl[ CHICASO $. ILliKOIS II WEST SUEET HO SOUTH MICHIGAK UEKUE TH.-WORTH 2- SU1 TEL .- WUHH lIli

    LOS ANGElES 11. CALIFORNIA UDO NORTH SEWUD SUHT TH.- HOLUWOOO lUI

    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