V 40 I.* JANUARY 1942 of . eng!rieering and manufacture radio communication, indLstrial applications eectjç. AL U. S. FDREST SERVICE AuToriAtIL: 111.1 STATION OPERATING IN 30-4C M R 'IC IC -1 t 'NAP' - *".4tOk ' V - 7 - . , `1.4 4, rf. 4,0". - - low - 411r..-t 441V- 4 - - 17174 'w,04016 " - , - 4 (7-- 1 s 1.4 ste , 1°' leb doesn the e tbodyngs tell me is an ideal source for transformers to specifications With improvements in materials, structural design, and production methods, UTC is pro- ducing, today, transformers which even a year ago would have been considered impossible. As a typ cal example of such development is a transformer recently supplied to a customer for one cycle operation having the following characteristics: Primary impedance IO ohms. Impedance ratio 75,000 : I. Secondary inductance 250,000 Hys. Self- resonant point above 7 cycles. Weight under 8 pounds. In additicn to t4,ese difficult characteristics, this unit operates at -160 DB signal level and hum shielding was developed to provide negligible hum pick -up to signal ratio. MAY WE ASSIST Y OU IN YOUR PROBLEM? The same design experience and engineering ingenuity shown in the above example can be applied to your application. May we have an opportunity to cooperate? 150 VARICK STREET EXPORT DIVI SiO1`: i00 YARICK STREET NEW YORK, N. Y. S: AR AB" electronics A McCRAW-HILL PUBLICATION CONTENTS-JANUARY, 1942 FOREST SERVICE RADIO Cover A field communication station of the U. S. Forest Service. Extensive use is made of radio in patrolling the forests and fighting Tres 30 -40 MC MOBILE RECEIVER, KEITH HENNEY by H. K. Lawson and L. M. Belleville 22 Editor An a -m receiver developed for use by the U. S. Forest Service under con- ditions heavy of ignition interference. Absolute signal values under I µ -volt Donald Fink Beverly Dudley a may be received on motor vehicles not equipped with spark plug suppressors Managing Editor Acting (on leave) Managing Editor BALLAST TUBE VOLTAGE REGULATORS, by S. Gordon Taylor 26 W. W. MacDonald Craig Walsh Automatic voltage regulation can be obtained in a number of devices by the use of a simple Associate Editor Associate Editor inexpensive iron wire ballast tube M. L. Mattey J. M. Heron SUPER -CARDIOID DIRECTIONAL MICROPHONE, by B. B. Bauer.. 31 Assistant Editor Assistant Editor An acoustical phase- shifting network is used to produce the effect of the combination of a velocity microphone with a pressure microphone Harry Phillips Art Director PHOTOFLASH SYNCHRONIZER TESTER, by P. A. Marsal 34 A device for measuring the time from the closing of the synchronizer switch to the instant when the camera shutter is opened to the desired degree SELF -CONTAINED MARINE RADIO UNIT 36 The high speed of producton of the Victory cargo fleet required the develop- ment of a quickly -installed radio transmitter and receiver unit such as the one described here H. W. MATEER Publisher RECTILINEAR RECTIFICATION APPLIED TO VOLTAGE Wallace B. Blood INTEGRATION, by S. S. Stevens 40 Sales Manager Non -linear rectifiers are combined in such a manner to produce rectilinear rectification and are used in conjunction with a condenser charging circuit to provide a voltage integrator with linear response COMMON MISAPPLICATIONS OF GASEOUS TUBES, by W. W. Watrous and D. E. Marshall 42 A discussion of the do's and don'ts of gaseous tube application TRANSMISSION LINE GRAPHS, by Bernard Salzberg 47 Contents Copyright, 1942, by Graphs for the determination of the characteristics of parallel wire or coaxial McGraw -Hill Publishing Company, Inc. transmission lines McGRAW -HILL PUBLISHING COMPANY, INC. DEPARTMENTS JAMES H. McGRAW Founder and Honorary Chairman CROSSTALK 21 THE ELECTRON ART 80 Publication Office REFERENCE SHEET 47 TUBES 94 99 -129 North Broadway, Albany, N. Y. U. S. A. TUBES AT WORK 50 NEWS OF THE INDUSTRY 100 Editorial and Executive Offices NEW BOOKS 62 NEW PRODUCTS 102 330 West 42nd St., New York, N. Y., U.S.A. INDEX James H. McGraw, Jr., President TO ADVERTISERS 114 Howard Ehrlich, Executive Vice President Mason Britton, Vice President B. R. Putnam, Treasurer ELFI,TRONICS, January, 1942. Vol. 15; No. 1. Published monthly, price 50c a copy. Allow at least ten days for change of address. A11 communications about subscriptions should be addressed to the Director of Cir- D. C. McGraw, Secretary culation, 330 West 42nd Street, New York, N. Y. J. E. Blackburn, Jr., Director of Circulation Subscription rates -United States and possessions, Mexico. Central and South American countries. $5.00 a year, $8.00 for two years, $10.00 for three years. Canada (Canadian funds accented), $5.50 a year. $9.00 for two years. $11.00 for three years. Great Britain and British possessions 36 shillings for one year, 72 shillings for three Cable Address: years. All other countries, $6.00 for one year, $12.00 for three years. Entered as Second Class matter, August 29, MCGRAWHILL, New York 1936, at Post Office, Albany, New York, under the Act of March 3. i879. BRANCH OFFICES: 520 North Michigan Avenue, Chicago; 68 Post Street, San Francisco; Aldwych House, Aldwych, London, W.C. 2; Washington; Member A. B. P. Member A. B. C. Philadelphia; Cleveland; Detroit; St. Louis; Boston; Atlanta, Ga. Rifid //, / //, %/ Tests Demand CENTRALAB Switches inrour Communication Systems Don't hold up defense development! Centralab NOW offers a kit of parts of high grade Steatite Ceramic Switch Sections and necessary metal parts which will withstand the 200 hour Salt Spray Test, for the immediate construction Important Features of in your own laboratory of efficient highest Centralab Selector Switches quality SELECTOR SWITCHES (over 200,000 1. High grade Steatite sec ^.ions, vacu- electrical combinations available). um wax impregnated. Whether it is the first 2. Contacts, clips, eyelets and rivets "hand made" transmitter heavily silver plated. or receiver, or whether they are rolling off 3. Complete index mechanism and your production line; if you equip them with operating shafts of stainless steel. these CENTRALAB Selector All brass parts heavily nickel Switches they plated to withstand 200 hour salt will pass every test for they are "BUILT FOR spray test. ABUSE ". For the first or thousandth unit . 4. Standard indexing 30° and 90° specify CENTRALAB SELECTOR between positions. Also available SWITCHES. in 60° on special request. Send for special bulletin on 5. Sections 3/16" thick. Mounting Selector Switches for Defense. center of sections 1- 9/,16 ". Over- all widest dimension 1 -7/8 ". CENTRALAB Division of Globe -Union Inc., Milwaukee, Wis. 6. Choice of 2 to 11 positions per section. 7. Kit consists of 61 Steatite Sections of various switching combinations, 36 indexes complete with hard- ware for assembling 1 to 6 sec- tions per index. 2 January 1942 - ELECTRONICS s° syntheticsynt . aper Papers . clear p Moat tcacMt of oll- OIL. kind <.IERAL e unstable. crystal-clear tracing with riyé ß11Y fI M treated cl cote' ties t, dries eral a decal °%rlf never In prcduc`Lte tcads to treated trans4arencY simple, wth sly e P r°° $ setmjr uP dust, age-proofs9 maties tree r ts orsa With ate. remark- orTec.icns, a sh2rp bluconstantc A,B NENE -:to wa= agent under handling. oa,ve No ,i', artizing to standup h 1f and rc 4.alites . Laboratories- owl,' all zblen'-`''nsñin Kg`E ment tracing all ttne working w ir ed ere 00 has develop tMs t. ul y perrr Of w s wanted-and initcl}' own produ- CNE is nade , yrh:t.ristics ijélf cu.) ou-: un- PAN t thew Cealer, chenticallY paper'- anite rags-treated a.IENEyoa' &E Papers treated pl;_ e crystal-c r -fry A Ask °°ur F+ OleßsilY rancid fiber d. Ted brochure oxidizes oil becomed opaque long n and chEml- stable. stable an rliTE-3 g with vegetableturn Ye11oW íoci- wri u for nr-p. and with l.ysica.ly not ate. cli3 P wt o awlf n with synthetic ' 6LBAlE1`E terns _terous 'lll/l' lose and a E,. calif irert. ljttttl(. OI ÉSgEß CO. become FEL w J. dite, wi_1 aage. has KO`_ REAI KEVfFEW tot MoNt a ALBAVENE or .s--r p "po_th" tañes ink cHICA60ANBtiS r 9ual y that ease 5 LOS sya -d "tooth es :itb FR+f+G -clear waa. ane ra- eras crYStal and o that fe a oil and from In ert. ße b .tifullo .ransparen-. pLBANITEsolid, freechemically pencil thetic an _ p ò FltyslcallY new sta.noaee isunot a degree { this Atbanen aih canes agent will or arentizi ;tsashlr clbe orne brittle affected by ate, otidise icß nsparefCY. Inge RE:J.U.S.O 1ç&EI L R C THE STABILIZE '-4/1/a4 aW-a/ t%e COMPENSATION FOR FREQUENCY DRIFT IN HIGH FREQUENCY COMMUNICATIONS ERIE CERAMICONS FREQUENCY drift in communications They are made in 9 standard coefficients oscillators is caused by physical and ranging from +.00012/ °C. to -.00075/ °C. electrical changes that occur in various Insulated Ceramicons are available in ca- components. While it is possible to elimi- pacities from 1 mmf. to 375 mmf.; non - nate the drift in each component, such a insulated units from 68 mmf. to 1100 mmf. procedure involves considerable re- design Erie Resistor has developed special and probable increased cost of each electronic equipment used in producing component affected. It is far easier to corn - and testing Ceramicons that insures a high pensate for the total drift by introducing degree of uniformity of characteristics in an Erie Ceramicon in the resonant circuit these units. This uniformity is essential for having a temperature coefficient of the dependable compensation in high frequen- opposite sign and of such a value as to cy communications equipment for Military offset the undesired drift.