ET/ II)

kit4,

4, # o. co*t.ne-0

NOVEMBER 1979 $1.00

ELECTRONIC TECHNICIAN/DEALER

LEADING THE CONSUMER AND

INDUSTRIAL SERVICE MARKETS

A HARCOURT BRACE JOVANOVICH PUBLICATION

Better thanbrand Send us your worn out tuners andbad modules. Your Zeniths. YourRCAs. Your Solys. Your Quasars,

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For the location nearest you, see Servicenter Guide on rext page.

PTSSERVICENTER

GUIDE

MIDWESTHome Guise

BLOOMINGTON, IN 47401..233 S Hwy 37, P O. 272

812.824-9331

CLEVELANDParma. OH 441345682 State Road

216-8454480KANSAS CITY, KS 66106

3119 A Merriam Lane. P 0 6149913-831-1222

MINNEAPOLIS. MN 55408815 W Lake SI.. P 0 8458

612.824-2333ST. LOUIS, MO 63130

8456 Page Blvd P.0 24256314 428-1299

DETROIT. MI 4823513641 W 8 -Mile Rd

311862-1783GRAND RAPIDS, MI 49501

1134 Walker NorthwestP 0 1435

616-454-2754CINCINNATI. OH 45216,72 Vine SI P 0 16057

513 821-2298MILWAUKEE. WI 53218

7211 Fond du Lac414464-0789

COLUMBUS. OH 432274005 A E Livingston

614-2373820INDIANAPOLIS. IN 462021406 N. Pennsylvania Ave

317-631-1551

DAVENPORT, IA 528032024 E River Dr.

319-3213975OMAHA. NE 68104

6918 Maple SI402 571-4800

CHICAGO, IL 606595744 N. Western Ave.

312.728-11300

SOUTHCHARLESTON, SC 29407

1736 Savannah Highway 17P O. 30511

803.571.7651JACKSONVILLE, FL 32210

1918 Blandong 131,70.. P O. 7923904189-9952

WASHINGTON, DCSilver Spring. MD 20910

8950 Brookville Rd.301.565-0025

CHARLOTTE, NC 282252542 Lucena SI. P.O.5512

704.332.8007BIRMINGHAM, AL 35201210 N. 9th SI.. P.O. 1801

205.323-2657MEMPHIS, TN 38118

3614 Lamar Ave.. P.O.18053901-3651918

NORFOLK. VA 235043118 W Princess Anne Rd.

804625-2030NEW ORLEANS

Metairie. LA 700043920A Airline Hwy.. P 0 303

504-837-7569TAMPA, FL 33690

2703 MacD111. P.O. 14301813.839.5521

NASHVILLE, TN 372142426 A Lebanon Rd.

515.885-0688

PACIFICSACRAMENTO, CA 95841

6131 Watt Ave P 0.X916 334 2012

SAN DIEGO. CA 921055111 University Ave P0.5794

714 280 7070

LOS ANGELESParamount. CA 907237259 E Alondra Blvd

213.634.0111PORTLAND. OR 972135220 N E Sandy Blvd

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215 352 6609PITTSBURGH. PA 15202

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ELMWOOD PARK, NJ 07407158 Market St . P 0 421

201 791 6380

BALTIMORE, MD 212155505 Reisterstown Rd P 0 2581

301-358.1186BOSTON

Arlington. MA 021741167 Massachusetts Ave P.0 371

617 648 7110

BUFFALO, NY 14214299 Parkside Ave

716-387.1656

MOUNTAINDENVER

Arvada. CO 800014958 Allison St

303.423.7080SALT LAKE CITY, UT 84106

1233 Wilmington AveP O. 6281

801 484 1451

PHOENIX. AZ 850092916 West McDowell Rd.

602.278-1218TUCSON, AZ 85719

801 E Broadway602-6245493

SOUTHWESTLONGVIEW, TX 75601

110 Mopac Rd . P.O.7332214 753-4334

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PTS ELECTRONICS, INC.

111DUSTRYREPORT

EDS Plans New Show FormatSponsors of the Electronic DistributionShow have announced that next year'sevent, May 1-3 at the Las Vegas Hilton,will operate under an entirely new for-mat.

According to EDS Executive VicePresident David L. Fisher, the showserves four basic electronics markets:The general line and MRO distributor;industrial electronic components; con-sumer products: and commercial soundand communications. EDS 1980, Fishersaid, will offer manufacturers four dif-ferent kinds of modes-booths, confer-ence rooms, hotel suites, and demon-stration rooms for those in commercialsound products.

All facilities, he added, will be underone roof this year at the Hilton Hotel. Theshow's theme is "Meeting the Challengeof Change."

Vote on IHF-EIA MergerVotirig on a proposed merger of the IHFinto the Electronic Industries Associa-tion is scheduled to be completedshortly. Plans for the merger wereannounced several months ago.

While IHF and EIA boards have giventheir support of the merger, consuma-tion of the proposals cannot be achieveduntil the IHF membership, comprised ofmanufacturers in the high fidelity -stereoarea, and the EIA Board of Governorsgive their approval.

Ballatine to Market JapaneseScopesBallantine Labs has announced plans tomarket a Japanese oscilloscope in thiscountry under the Ballantine name.

Under an agreement with Iwatsu Elec-tric Co., Ltd., Japan, Ballantine will mar-ket "selected" Iwatsu test instrumenta-tion, a spokesman said. The first instru-ment will be a dual -trace, 40MHz scopeto be known as the Ballatine 1042A. Thislatter unit, Ballantine said, is a "naturalcomplement to Ballantine's existing lineof oscilloscopes which includes the ...1020 series Travelscopes-12MHz dualand single trace miniscopes, and the1030 series 20MHz dual and singletrace portable/bench scopes.

Iwatsu Electric Co. was established in1938 and makes a broad line of scien-tific, industrial and commercial productsfor international distribution. iwatsuproducts include telecommunicationsequipment, electronic test and measur-ing instrument and information process-ing equipment.

The model 1042A, Ballantine reports,features independent dual triggering for

simultaneously viewing two asynchron-ous signals. This capability has becomenecessary, the company said, becauseof growing service needs in computerperipherals and disc memories.

Racal -Dana announces LifetimeGuaranteeRacal -Dana Instruments, Inc. has an-nounced a lifetime guarantee in associa-tion with the introduction of its new 99Hundred series of frequency counters.

The guarantee, a Racal -Danaspokesman said, applies to the LSI chipwhich comprises the central logic unit onits new line, comprised of eight fre-quency counters covering the HF/VHFand UHF bands up to 3GHz. The chip, adedicated bipolar device, is made byFerranti Electronics Ltd.

According to the company, statisticalinformation on LSI devices similar tothose used in the new Racal -Dana lineshow a chip life of more than 20 years."Our own experience," according toRacal -Dana President Webb Scroggin,"using 10,000 such chips over the lastfew years without a single failure rec-orded, confirms this high reliability.

The company said every counter inthe series uses the custom designedchip which features collector diffusionisolation. It operates at speeds up to60MHz.

Satellite -to -home pay TVComsat Corporation is reportedly dis-cussing a satellite pay TV subscriptionservice with suppliers of both hardwareand programming. This programmingwould be broadcast from satellite di-rectly to the subscriber's roof mountedantenna. Experimentally such a serviceis presently being tested in Japan andCanada. A Comsat spokesman statedsuch service could be introduced in theU.S. by 1983.

Sinclair Sells TV businessSinclair Radionics, maker of electroniccalculators, digital multimeters andcounters, has announced it is ending itsinvolvement in the consumer electronicsmarket with the sale of its television re-ceiver business.

Sinclair made that exceptionallysmall, two inch black and white batterypowered, unit which sold orignally for$395 and was capable of reception on

Circle No. 102 on Reader Inquiry Card ETID - November 1979 / 1

RICHARD W. LAYEditor

WALTER H. SCHWARTZManaging Editor

JOHN GOOLEYContributing Editor

DAVID J HAGELINPublisher

TOM GRENEYPublishing Director

JOHN PASZAKGraphic Design

KATHY TARNOWSKIProduction Manager

LILLIE PEARSONCirculation Fulfillment

On the cover: RCA'sStacom Ill, scheduled to be

launched next month, isshown in space through the

magic of an artist's brush.Representative of the "new

technology" in T V signaldistribution, it serves as a

lead-in to this month's articleon private, home television

reception from space.

TI ELECTRONIC TECHNICIAN/DEALERLEADING THE CONSUMER ANDINDUSTRIAL SERVICE MARKETSNOVEMBER 1979, VOL. 101, NO. 11FEATURES

Statellite television receptionPrivate home receiving rigs are here 20

Microprocessors from A to ZA stand alone introductory series begins 24

Digital electronicsBasic digital counters and their operation 28

The world of medical electronicsAnother profit area for you? 34

What's new in telev;sionChecking out RCA's CT101 38

DEPARTMEATSINDUSTRY REPORT

FROM THE EDITOR'S DESK

NEWSLINE

LETTERS

SERVICE SEMINAR

STRICTLY BUSINESS

TEST INSTRUMENT REPORT

NEW PRODUCTS

CLASSIFIED ADS

AD INDEX

READERS SERVICE

TEKFAX

1

8

10

13

_15

19

42

43

48

50

51

53

H B J A HARCOURT BRACE JOVANOVICH PUBLICATION ):,ABP Eu

ELECTRONIC TECHNICIAN/DEALER (ISSN 0192-7175] is published monthly by Harcourt Brace Jovanovich Publications. Corpo-rate offices: 757 Third Avenue. New York, New York 10017. Advertising offices: 757 Third Avenue, New York, New York 10017 arid111 East Wacker Drive, Chicago. Illinois 60601. Editorial offices: 111 East Wacker Drive. Chicago, Illinois 60601. Accounting,Advertising Production and Circulation offices: 1 East First Street, Duluth, Minnesota 55802. Subscription rates: one year, $10; twoyears, $16; three years, $20 in the United States and Canada; all other countries: $45. Single copes: $1 in the United States andCanada; all other countries: $3. Controlled Circulation postage paid at Dansville, New York 14437. Copyright c 1979 by HarcourtBrace Jovanovich, Inc. All rights reserved. No part of this publication may be transmitted or reproduced in any form or by any means,electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission inwriting from the publisher. ELECTRONIC TECHNICIAN/DEALER is a registered trademark of Harcourt Brace Jovanovich, Inc.

POSTMASTER: Send Form 3579 to ELECTRONIC TECHNICIAN/DEALER, P.O.Box 6016, Duluth, MN 55806.

2 I ETD - November 1979

special2SC1308K SanyoHorizontal Output TransistorEquivalent to ECG 238

SanyoNumber Specifications Equivalent To Replaces Price

C1025 VcBo 200V ECG 175 Most H, V DEF. out.Ic 3A, PC25W TO -66 put transistors and

more. Includes C1160..95

C1161, 0130, D291.

* 0386A VcBo 200V ECG 375 Most vert. outputIc 2A, Pc25W transistors Included. 1.40

C1308K VcBo 1500VIc 7A. Pc5OW

ECG 23810.3 case

Most horizontal out.put transistorsincluding C1358,C1172, C1172B. D350

2.90

A1011 VcBo 180V TO.220 case 8538, 8537, A913.Ic 1.5A, Pc25W Used for AF driven .75

PNP.

C2344 VcBo 180V 10.220 case 0381. 0382, C1447.Ic 1.5A, Pc25W Used for AF driven .75

NPN.

8507 VcBo 60V ECG 153 B511. 8512, 8513.Ic 3A, Pc3OW TO -220 case 9514, B515, AF

output.70

.90Minimum order of 10.

SanyoNumber Specifications Equivalent To Replaces Price

D313 VcBo 60V ECG 152 0234, D235, 0314,Ic 3A, Pc3OW TO.220 case 0325, 0330, 0331,

D317. D318..55

8633 VcBo 100y ECG 197 Most of 10.220 caseIc BA, Pc4OW 10.220 case PNP Audio output

transistors..90

0613 VcBo 10011 ECG 196 Most of 10.220 caseIc BA, Pc4OW TO.220 case NPN Audio outputs. .80

8697K VcBo 180V ECG 281 Most of 10.3 caseIc 12A, Pc100W TO -3 case PNP Audio outputs. 2.50

STRONG!

D733 VcBo 180VIc 12A, Pc100W

ECG 28010.3 case

Most of 10.3 case NPNAudio outputs, includes 2.45C1079. C1080, D118,0425. 0429 0371. D217.

024Y VcBo 300VIc150MA. Pc65W

ECG 124TO -66

C515A, C685A. HVAudio power outputfor TV.

.75

Our huge buy of popularfuses makes the prices too good for you to PASS UP!ACG Style Amps: .511/1.5/2/3/4/5/6/7I(10 to 100) 126 each (100 up) 86 each

GMA (F Type) Amps: .11.51111.512/2.513141516171(10 to 100) 186 each (100 up) 14s eachMinimum order of 100 of each

Special prices available for OEM end distributors. Call Toll Free number for information.

ECG Equivalents at Huge Savings!Here is a list of In -stock ECG equivalents. We also have hundreds of semiconductors not listed here.Write for free 20 -page catalog or receive it free with each order.

Equk To Price Equk To Price Equk To Price Equk To Price Eqult To Price Equiv. ToPries Equk To Price Equk To Price Equk To Mu Equls To Pries Equk To Price

102 .40 163 4.60 237 2.40 323 2.20 737 3.80 941 .75 1035 4.701081A 2.30 1129 7.40 1178 3.40 1219 8.60

103 .70 184 3.35 238 3.35 324 2.50 738 490 966 2.80 1036 5.60 1082 1.301130 4.20 1179 2.60 1220 9.40

104 1.35 165 3.35 276 7.90 376 2.25 739 3.20 973 1.80 1037 3.001085 1.301131 4.40 1180 2.70 1222 3.95

105 3.90 171 1.60 277 5.80 500A 12.40 740 280 973D 2.00 1038 4.70 1087 1.30 1132 4.201181 3.40 1223 2.90

106 .40 175 2.90 279 7.40 506 1.50 742 4.20 975 1.60 1040 1.40 1089 6.401133 3.80 1182 7.60 1224 3.20

107 .80 177 .25 280 2.70 526 18.80 743 1.50 976 1.60 1041 1.20 1090 9.60 1134 4.401183 4.90 1228 2.90

108 1.20 180 2.80 281 2.80 551 2.00 744 5.20 978 1.60 1042 2.40 1091 3.90 11351.90 1184 2.95 1230 2.20

109 .20 181 2.70 282 200 601 .30 746 3.80 987 1.40 1043 4.40 1092 1.50 1137 1.901185 2.40 1232 5.60

110 .40 182 3.20 283 4.80 605 1.65 748 2.80 1002 1.301045 2.60 1093 2.40 1140 1.60 1186 2.75 1234 1.30116 .20 183 3.75 284 4.30 612 .35 749 2.90 1003 1.30 1046 3.20 1096 3.65

1142 1.40 1187 2.75 1235 1.20

117 .20 184 1.00 285 6.20 613 .40 778 1.80 1004 2.20 1049 3.90 10978.80 1148 14.60 1188 3.50 1236 2.90

121 2.75 185 1.00 287 .70 703A 1.50 780 3.20 1005 2.20 1052 1.50 1098 7.851149 3.90 1189 8.60 1237 2.00

123A .35 186A .60 289 .55 708 1.50 783 3.20 1006 2.20 1053 2.40 1100 1.401150 2.20 1190 6.20 1238 3.40

124 1.95 187A .80 290 .40 709 1.50 788 1.50 1009 2.20 1054 1.701101 1.90 1153 2.50 1191 7.90 1239 2.90

125 .20 190 1.00 291 1.30 710 3.00 790 2.80 1010 2.20 1055 2.70 11021.40 1154 2.80 1192 1.30 1240 2.20

126 .80 192 .45 292 1.50 711 3.95 791 2.80 1011 2.20 1056 2.801103 1,20 1155 2.10 1193 2.40 1241 2.20

127 2.95 193 .55 293 .45 712 1.50 793 3.20 1012 .95 1057 3.151104 1.20 1158 3.40 1194 2.20 1243 2.30

128 2.50 196 1.30 294 .40 713 1.50 801 1.50 1013 1.30 1058 1.951105 3.801159 3.40 1196 8.60 1244 4.80

129 2.20 197 1.50 295 .60 714 1.50 802 8.80 1014 1.90 1060 1.30 1106 2.75 1160 2.301200 6.40 1252 7.50

130 1.00 198 1.50 297 .65 715 3.20 803 4.80 1016 2.20 1061 3.95 1108 2.601161 6.60 1205 3.00 1256 2.80

131 1.00 199 .30 298 .70 718 1.50 804 4.20 1019 1.30 1062 4.201109 3.90 1162 2.40 1206 3.90 1259 2.80

132 .60 220 1.60 299 .75 719 1.50 805 3.20 1020 2.20 1063 4.90 1110 7.801163 3.90 1207 5.50 1260 2.90

133 .60 221 1.40 300 .70 720 1.50 806 3.80 1021 2.20 1067 5.70 1115 2.40 11645.40 1208 3.30 1261 2.90

152 .80 222 1.60 302 1.00 721 3.80 807 3.20 1024 4.20 1069 9.301115A 2.40 1165 2.20 1209 3.20 1301 3.20

153 .95 226 '1.00 306 1.30 722 1.50 812 4.00 1025 5.90 1070 3.80 11162.80 1188 2.30 1210 2.60 1304 14.50

155 2.90 229 .80 307 .50 723 1.50 814 4.20 1028 1.20 1071 4.801117 2.80 1167 5.60 1211 3.10 1308 5.90

157 2.25 230 4.80 308 7.40 724 2.80 818 3.80 1027 4.90 1072 2.90 11224.40 1168 5.40 1212 8.40 1312 5.90

158 .40 231 4.90 310 7.40 725 1.50 824 2.50 1028 9.20 1073 1.60 1123 6.10 11693.00 1214 5.50 1312 5.90

159 .60 233 .80 312 .60 726 3.50 912 2.40 1029 2.60 1074 2.801124 2.90 1170 2.90 1215 2.60 1313 5.90

160 1.80 23/ .40 315 1.00 729 4.20 917 3.20 1030 5.40 1075A 2.80 1126 4.20 1171 4.401216 3.60

161 1.20 235 1.80 320 10.60 731 1.50 923 1.00 1032 2.90 1078 7.40 11272.30 1172 4.60 1217 120

162 4.60 236 2.30 321 3.60 733 2.80 925 8.00 1034 4.70 1080 3.201128 1.75 1173 2.90 1218 5.50

ECG is a registered trademark of the Sylvania Corporation,

Call These Toll -Free 24 Hour Hot Lines

1.800-543-3538 or 1-800-543-3528( In Ohio call 513-254-6283) TI. X 288349

ralmom audio, Inc.Your original Japanese semiconductor supplier639 WalvvOiri PAv . Dayton. Ohio 45420

Circle No. 117 on Reader Inquiry Card

ET/D - November 1979 / 3

Facts from Flukeon low-

cost digital multimeters.When you're looking for genuine

value in a low-cost DMM you have alot more to consider than price. Youneed information about ruggedness,reliability and ease of operation.Accuracy is important. And so arespecial measurement capabilities. Butabove all, you must consider thesource, and that company's reputationfor service and support.

Fact is, as electronics become morea part of our daily lives, dozens of newmanufacturers are rushing to markettheir "new" DMM's. In theory, this ishealthy; but in practice, crowding isconfusion.

To help you deal with this flood ofnew products, here are some facts youshould know about low-cost DMM's.The economics of endurance.

Even the least expensive DMMisn't disposable. Accidents happen, andtest instruments should be builtto take the abuses of life as welive it.

Look for a DMM with alow parts count for reliability,and rugged internal construc-tion protected by a high -impactshell. Make sure the unit meetssevere military tests for shockand vibration.

Another feature to check outis protection against overloading,whether from unexpected inputs,transients, or human errors.

Just for the record, all Flukelow-cost DMM's meet or exceedmilitary specs, and feature extensiveoverload protection.

The importance of being honest.Just because a multimeter is

digital doesn't mean it's automaticallymore accurate than a VOM - eventhough the LCD might give you thatimpression. The benchmark foraccuracy in DMM's is basic dcaccuracy. The specs will list it as apercentage of the reading for various dcvoltage ranges.

Of course accuracy is more criticalin some applications than others, andincreasing precision and resolution in aDMM usually means increasing price.In the Fluke line, you can choose amodel with a basic accuracy of 0.25%(the 8022A), others rated at 0.1%, or thenew 8050A bench/portable at 0.03%.Special measurements:getting more from your DMM.

Actually, for all the variations insize, shape and semantics, mostDMM's perform five basic measure-ments: ac and de voltage and current,and resistance. Prices vary accordingto the number of ranges and functionsa DMM delivers.

.)6-Q,

e

Xcelite'service

master kits

all the electronicservice tools you need99% of the time

Model 99SMW adds new dimensions tothe serviceability of Xcelite's famous andstill available 24 -piece 99SM ServiceMaster Set.

Housed handily in the same type ofroll -up, plastic -coated, canvas case, the27 -piece 99SMW adds a Weller WP25professional, pencil -style soldering ironwith an extra, wider tip, and a No. 100wire stripper/cutter. These plus the tra-ditional 99SM tools that thousands ofservicemen and technicians have likedso much so long: 20 Xcelite Series99 quick -change, interchangeable bladetools -popular size nutdrivers, slottedand Phillips type screwdrivers, exten-sion, reamer, regular and stubby handles;diagonal and long nose pliers; thin -pattern, adjustable wrench. The handiesthandful of service tools you've ever laidyour hands on!

in stock at leading electronicdistributors ... nationwide

COOPER,NPUSiRifS

TheCooperGroupElectronics Division

WELLER'WISS' XCELITE'PO BOX 728. APEX. NORTH CAROLINA 27502. 91%362-7511

Circle No. 108 on Reader Inquiry Card

6 / ET/D - November 1979

both the NTSC and PAL systemsthrough a front panel switch adjustment.However, the unit will still be aroundsince the new owner, Binatone-anaudio marketer-plans to plans to pro-duce the TVs.

In another development, the founderof Sinclair Radionics, Clive Sinclair, hasannounced he has left the original firmand formed Sinclair Research. Throughthe latter corporation he plans to dodevelopment work on a flat tube minia-ture television.

Mitsubishi Opens U.S.HeadquartersMitsubishi Heavy Industries, Ltd., one ofwhose divisions makes MGA televisionreceivers, has announced it is opening aU.S. headquarters in Chicago.

However, a spokesman said, the ven-ture at this point in time has nothing to dowith the television business. The pri-mary purpose of the headquarters willbe to coordinate the efforts of Mit-subishi's five other U.S. offices in provid-ing after sales service to customers of itsindustrial machinery products.

Mitsubishi, with sales of some $12.6billion annually, makes ships, airplanes,heavy machinery, trucks, cars, buses,power systems and consumer products.The Chicago office, to be headed byYutake Aoki, president of MitsubishiHeavy Industries of America, will becomprised of eight persons, a companyspokesman said.

Philips Seeks Larger TestInstrument Market ShareNorth American Philips' new manu-facturing facilities in the United Stateswill initially concentrate on making 25 to50MHz bandwidth ocilloscopes, accord-ing to President Dominick Protomastro.

The plants, the first manufacturingoutlets for North American Philips in theUnited States, eventually will expandtheir capabilities to include scopes in the100MHz frequency range, he said. Thenew sites, located at Mahwah, N.J., arepart of Philips' overall plan to capture a"substantially" greater share of the U.S.test instrumentation marketplace, Pro-tomastro contends. He said that marketis "burgeoning."

He added that the U.S. plants willhave their own engineering capabilities"to satisfy the unique demands of theU.S. market and to support the manufac-turing operations."

Last year North American Philipsachieved record high sales of $2.2 bil-lion. ET/D

CorrectionThe correct chassis numberfor the Hitachi Color TVreceiver in SeptemberTEKFAX is NP8SX, notNP4SX.

T/n.Richard W. Lay, Editor(Chicago)

Walter H. Schwartz, Managing Editor(Duluth)

David Hagelin, Publisher(Chicago)

Tom Greney, Group Vice President(Chicago)

John Paszak, Graphic Design

Kathy Tarnowski, Production Manager

Debi Harmer, Production Supervisor

Lillie Pearson, Circulation Supervisor

Gene Bailey, Reader Service

Julie Laitin, Promotion Director

Dawn Anderson, Classified Ad Mgr.

Please submit editorialmanuscripts to:Editor, ET/D, 111 East Wacker DriveChicago, III., 60601

ADVERTISING SALES

Please send all advertising material to:ET/D, Production Mgr.120 West Second StreetDuluth, Minn. 55802(218) 727-8511

East RegionThomas Palmisano757 Third AvenueNew York, N.Y. 10017(212) 888-4382

Midwest RegionDavid J. Hagelin111 East Wacker DriveChicago, III. 60601(312) 938-2325

Southern & Western RegionChuck Cummings613 N. O'ConnorIrving, TX 75061(214) 253-8678

Sheila Connolly10741 Moorpark St.North Hollywood, CA 91602(213) 980-7750

1111j

HARCOURT BRACE JOVANOVICHPUBLICATIONS

Robert L. Edgell, ChairmanRichard Moeller, PresidentLars Fladmark, Senior Vice PresidentArland Hirman, TreasurerThomas Greney, Group Vice PresidentEzra Pincus, Group Vice PresidentLois Sanders, Group Vice PresidentJoe Bilderbach, Vice PresidentJames T. Gherna, Vice PresidentGeorge A. Glenn, Vice PresidentHarry D. Ramaley, Vice President

SY

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it'sS

ylvania to therescue. O

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guideis the

most used,

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industry. It makes

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performer w

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When itcom

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picture tubes,receiving tubes,

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FROMTHE

EDITOR'SDESK

The high level of technology now associated with consumerelectronics products has forged a new breed of homeentertainment electronics technician almost overnight. In additionto being young, aggressive, and ambitious, this new breed oftechnician has been "brought up," as it were, in the fast movingworld of modern electronics. He is equally "at home" working ondigital or analog circuitry, he understands basic microprocessortheory and he is willing to learn more about the ever changingelectronics world which surrounds him.

Those who hesitate to follow in his footsteps will find their daysare numbered indeed.

To those in the latter group, I believe this issue of ET/D may beparticularly significant. For one thing, it carries the seventh, andfinal installment of Joe Carr's excellent series on digital electronicsbasics. It is the second such series he has done for ET/D. If youhaven't yet "picked up" on earlier installments you may do so byobtaining back copies beginning with the May issue.

Beyond this, the November issue offers the first installment ofanother series, I believe a tremendously significant series, on themicroprocessor. Written by Bernard Daien, it may well be the lastchance, for those who have hesitated in learning about the newtechnologies, to "jump in" and start swimming.

While we will run other more advanced stories aboutmicroprocessor -controlled products concurrently with this series,the latter is specifically designed for the novice in this area whohas no prior experience-even insofar as the terminology isconcerned. In effect, this series will take you from "day one," up tothe present and then point you toward the proper resourcematerial to continue your education.

And in case you haven't noticed it, continuing education hasindeed become the name of the game in modern electronics.

In this issue also you will find an article dealing with thereception and demodulation of television signals from satellites inspace. For several years now the major networks, as well asothers, have used these devices for the intercontinentaltransmission of television programming. Now, however, there is anew wrinkle in that economically feasible earth receiving stationsare within reach of the individual. While they aren't cheap by anymeans, there are "home receive" stations in existence today in theUnited States. Their owners enjoy the convenience of programselection beyond anything offered to date by anyone else.

Is this a wave of the future? Who knows? The point is it couldbe and in this regard ET/D feels a responsibility toward keepingyou informed as to just what is going on in the area of satellitetransmission and reception.

8 / ETID - November 1979

Mallory Fastenersfit rightin anywhere.Mallory's got just about every kind you need -clamps, clips, wire saddles, ties, cable hangers, cir-

cuit board supports, guides and dozens of others.Add to this complete line, the right prices, and

packaging in bulk or convenience packs, andyou can see why our fasteners fit anywhere.

See your Mallory Distributor. Or contactMallory Distributor Products Company, a divisionof Mallory Components Group, Emhart Indus-tries, Inc., P.O. Box 1284. Indianapolis, Indiana46206. (317) 636-5353.

Circle No. 116 on Reader Inquiry Card

noustinsZENITH-SCHLUMBERGER FINALIZE DEAL. Zenith Radio Corp. has announcedthat its acquisition of Heath Company, a wholly owned subsidiary ofSchlumberger Limited, has been completed. Heath, the marketer ofelectronic kits under the Heathkit name, is based in St. Joseph,Mich. Long term financing for the $64.5 million deal has beenarranged through Prudential Insurance Company.

NEW ZENITH UNIT TO FOCUS ON MICROCOMPUTERS. The speculation hadbeen that acquisition of Heath Company's small computer line was thekey motive in Zenith's takeover. Incidentally, Zenith also makescathode ray tubes for industry and computer displays. Zenithannounced creation of a new data systems division under the direc-tion of Edward J. Roberts who has been Zenith's treasurer since 1975.Zenith Board Chairman John Nevin said Roberts would concentratetechnical and marketing resources on the "significant growth oppor-tunities in the small computer systems field."

SONY -PHILIPS CONCLUDE PATENT AGREEMENTS. What could turn out to bea key move in the battle for market share for new and developingconsumer products --such as video disc players and Pulse CodeModulated stereo systems --has been announced by N. V. Philips andSony. The two foreign electronic industry giants have announcedplans to trade patent rights for some of their products. The moveis seen as an effort to standardize, and make compatible, their newproduct lines.

MATSUSHITA-RCA COMBINE. A somewhat similar --though legally unstruc-tured alliance -- exists between Japan's electronic/industrial giantMatsushita Electric and RCA. Matsushita --which markets consumerelectronics in this country under the Panasonic and Quasar brandnames --already is a large supplier of home video tape recorders toRCA. Also, RCA is planning to introduce its own version of a videodisc player -- using a different, uncompatible technology thanPhilips --later this year. Matsushita is currently developing avideo disc system.

HOME VIDEO RECORDING GETS LEGAL OKAY. Mickey Mouse took it on thechin in a decision handed down by Federal Judge Warren Ferguson inLos Angeles. In a ruling that surprised hardly anyone, the judgesaid it is not illegal for the owners of home video recorders totape off the air for non commercial use. The ruling came in asuit by Walt Disney Productions to prevent Sony Corporation --makerof Betamax video recorders --from making them.

NEWS IN BRIEF...WESCON, the high technology electronics hardwareconvention for engineers and technicians reported record attendanceof well over 50,000 for this year's event in San Francisco...NipponElectric of Japan, that nation's largest maker of semiconductors,says it will start making large scale integrated circuits next monthat its California subsidiary --Electronic Arrays, Inc...and, AmericanExpress company has acquired 50 per cent of Warner Cable from WarnerCommunications. The cable company involves some 140 cable TVsystems serving over 600,000 thousand subscribers.

10 I ETID - November 1979

150,000 REASONS WHY YOUSHOULD SWITCH NOW TO THEBIGGEST, BROADEST -EVERLINE OF ZENITH UNIVERSALSEMICONDUCTORS coveringZenith exact replacements plusthe most popular types in theindustry -all in a new catalog!

DEVICE

SKSK3313/116SK3119/113SK3115/165

3444/123A 12

103.101

602211221.1;SK3452/108 1.290MA

121.522

SK3051/156 121 29004212:29000

SK3SK3068/118

212.85

SK3100/519'988'03103.131

It's all under one numbering system that saves youtime and adds value to any Zenith semiconductoryou may already have in stock!

Switch now to Zenith Universal Semiconductorreplacements and see how well your shop shapesup...your bottom line, too.

Check with your Zenith distributor for your copy of Zenith's UniversalSemiconductor cross-reference guide...and ask how you can enjoythe convenience of our special Tube Caddy/Benchtop Organizer.ECG is a registered trademark of GTE SYLVANIA

212-o000

Shown here are just a few of the more than150,000 cross-references in the July, 1979

edition of the Zenith Universal Semiconductorcross-reference guide.

I'll/TMThe quality goes in before the name goes on

Zenith Radio Corporation /Service, Parts & Accessories Division /11000 Seymour Avenue /Franklin Park, Illinois 60131Circle No 126 on Reader Inquiry Card

2NNIVERE1Y

The LeaderScopeLBO -515A25 MHz, Delayed Sweep,Dual Trace Calibrated delayed sweep. 5 mV/div vertical sensitivity. Rectangular (8 x 10 divisions)

CRT with internal graticule. 14 nSec rise time. Variable "hold -off" control. H.F. filter plus TV sync. assures

stable displays. Selectable synchronization,

automatic, normal, single traceand reset modes.

$1,530.with accessories

The LeaderGeneratorLCG-396

$995.See your distributor for details on Leader's complete line of "VTR Approved"

test instruments...all with the finest 2 -year warranty available today.

The LeaderCounterLDC-8227 -Digit FrequencyCounter withPeriod Function 20 mVrms sensitivity-variable. Period function. 5 ppm accuracy. Bright 1/2" display. High reliablity, LSI circuitry. Gate time indicator. 1 M -ohm input impedance. Overrange indicator. $300.

with accessories

NTSC ColorPattern Generator NTSC color bars and staircase. 75 -ohm video and RF output. Equalizing pulse phase locked to

color sub -carrier. Provides full -field for IOW

insertion, plus on -off control ofchroma and luminance.

Accurate checking and adjustingof purity and white balance viared, blue, green, white rasters.

Dots and single crossbars forconvergence, raster and all otheralignment requirements.

Progressive or interlacedscanning.

Comprehensive instructionmanual (available separately,$15.00).

LEADERInstruments Corp.

12 / ET/D - November 1979

380 Oser Avenue, Hauppauge, New York 11787 (516) 231-6900Circle No. 114 on Reader Inquiry Card

LETTERSHELP NEEDED:I am in need of service data for a porta-ble color television manufactured underthe name XAM, and sold by Korvettes.The model number is 18CP4 and it wassold in 1974-75.Frederic Stern209-15 18th Ave.Bayside, NY 11360

I need information on an XAM model14CP74, bought in 1974 from Korvet-te's.Ralph E. Weidler7424 Warren St.Forrest Park, IL 60130

Editor: ET/D contacted Korvettes andfound them most cooperative. For ser-vice information or parts contact:Korvettes, TV Parts Dept.99 Constable Hook Rd.Bayonne, NJ 07002,giving model number. If they cannotsupply parts any longer for an oldermodel, they will, we are assured, supplythe name of a supplier who can.

I need a medallion (complete radio dialface -glass) for a GE Model T1001Cstereo radio cabinet. It can be used. GEcannot supply this item.Randall Robertson, Service Manager107 W. Vine St.Salisbury, MD 21801

I need help in obtaining the latest tubechart information for a Jackson TubeTester G48 -1T. I will gladly pay for it.Daniel T. BrownDanny's TV Sales922 0 15th St.Portsmouth, OH 45662

I have two 5 in. black and white CandleTV's in the shop that have vertical prob-lems. I have not been able to get anyservice data on these sets. The model is510A. If any of your readers can help meI would appreciate it.Anthony Christifano446 N. DenverKansas City, MO 64123

Needed: A schematic or service manualfor a Bradford Model 1004P41 (WTGrant WTG 609). Will pay for copy.Race Radio & TV3274 Mission St.San Francisco, CA 94110

Help! I need a TV tuner KRK168 &KRK167. New or used.M. Hardecker805 Stiles Ave.Maple Shade, NJ 08502

Would you please put the following inyour letters department. Needed:Schematic -service manual for an Edi-son radio receiver Model R5 and anEdison power unit Type 8P, ReceiverType 7R. Will buy or copy and return.Jerome Galiley1303 TustinCardiff, CA 92007

TEKFAX NEEDED:I would like to obtain TEKFAX's #109,110, 111, 112, 113D & R TV1004 CommercialJensen Beach, FL 33457

I need TEKFAX #113Lee B. Britton6260 Church St.Los Angeles, CA 90042

ET/D welcomes letters from readersand tries to answer all requests in thiscolumn or individually. ETD

Hook up to TUSA for the latest in MATV products

New Eagle series distribution amplifiers

EAGLE SERIES

BROAD BANDDISTRIBUTION AMPLIFIER

VHF 1 6dbMODEL DA751 6

Everyone knows TUSA for its qual-ity, reliable, advanced -engineeredproducts, but here's a new addition tothe line - the Eagle Series of distribu-tion amplifiers. The Eagle Series dis-tribution amplifiers can handle 30 vhfchannels simultaneously with no per-ceptible distortion or interference.And they're ideal for multi -outlethomes or apartments in which a hook-up is made to a master antenna orCATV system.

Three vhf TV distribution amplifiersare available: Models DA -7508, DA -7516 and DA -7524. All are 75 -ohmunits with gains of 8, 16 and 24 dBrespectively. Maximum output is 52dBmV and noise figure is 7 dB on all

three models. The amplifiers are keyhole -punched for easymounting and are completely shielded.

So see your TUSA distributor today, and hook up to themost reliable line in MATV. Trans USACorporation, 158 Tices Lane, East Bruns-wick, N.J. 08816 (201) 254-3020.MilifFrom Trans USA

Circle No. 123 on Reader Inquiry Card

ETID - November 1979 / 13

SYLVANIA ANNOUNCES

The Two forBlue Hawaii c-ni

Super SemiconductorSweepstakes.

The Sylvania Super Semiconductor Sweepstakes program is available only to dealersand service technicians Employees of General Telephone & Electronics. GTE Sylvania.their subsidiaries, authorized distributors, or their advertising agencies are not eligible toparticipate No purchase required. Reasonable facsimile accepted. Void in Utah, andwhere prohibited by law

PRIZES INCLUDE: First Prize: A trip for two to gorgeous

spectacular blue Hawaii. One 1st Place Award Trip for two to Hawaii Four 2nd Place Awards Play Master Slate

Pool Table Five 3rd Place Awards Weatherby Olympian

Over/Under Shotgun Five 4th Place Awards Motobecane Moped Ten 5th Place Awards AMF 10 -Speed Bicycle Fifteen 6th Place Awards Weber Bar-B-Que Kettle Sixty 7th Place Awards Jiffy Grass Trimmer 2200 8th Place Awards Cordomatic Power

Outlet Reel

There will be winners from every state* -2300 winners in all.

Enter as many times as you wish toimprove your chances of winning.To enter send in five Sylvania ECG'semiconductor bags or cartons attachedto an official entry form. Official entryforms are available from Sylvania distrib-utors. Mail to "Sylvania SemiconductorSweepstakes Award Headquarters", P.O.Box 4900, Fenton, Mo. 63026.

SYLVANIA

All entries must be postmarked no later than midnight, December 31, 1979.

SERVICE SEMIRRItCOPING WITH AMP INTERFERENCE

Ideally, audio equipment should be immune to radio -frequency interference and unwanted external noise. In aneffort to ensure that it is, many counter-measures are beingtaken in the design and manufacturing of the equipment.However, due to the high cost involved, it is impossible toeliminate all sources of interference. Radio -wave pollution iseverywhere. In addition to numerous public broadcasting sta-tions, there are many business and amateur stations as wellas citizens' band users, all contributing to it.

The major causes of interference are excessively high -power transmission, spurious radiation, transmitters locatedtoo close to receivers and poor receiver protection. However,before the problem of interference can be tackled, the inter-ests of all parties concerned -users, broadcasters andmanufacturers -must be taken into consideration. Here we willdiscuss the various countermeasures currently being takenagainst external noise and interference. But first let us explainthe meaning of "Amp I."

"Amp I" stands for Amplifier Interference. It is a kind of RFinterference, and refers to RF energy transmitted at a high -enough magnitude to interfere with the operation of electronicequipment, in this case audio equipment.

The cause of this interference can come from any one of avariety of sources in which RF energy is detected. And theeffects can be noticed in virtually every piece of audio equip-ment.

Although "Amp I" can be classified in various ways, such astape deck or tuner interference, for the sake of simplicity weshall refer to everything collectively as "Amp I" here.

1. "Amp I." Its Main Causes and Entry Points1.1 Main causes of "Amp I"o Connecting cords used between components in an audio

system may, due to their stray capacitance and induc-tance, act as resonant circuits for RF signals. When abroadcast frequency is picked up by the resonant circuit,the signal passes through the cords and enters the sub-sequent circuit, where it is detected and amplified by thevarious circuit components such as transistors and IC's.

o Powerful RF signals may enter directly into the circuitelements, bypassing the normal inputs. Phono cartridges,magnetic heads and circuits with non-linear amplitudecharacteristics are particularly susceptible to such inter-ference.

o Incorrectly operated broadcasting equipment, or equip-ment that is incomplete or insufficiently protected againstspurious radiation, causes RF signals to be induced intoAC lines. This results in unwanted external noise andinterference in audio equipment, TV's and other audiotransducers in the immediate vicinity of homes usingcommon lines.

1.2 Major "Amp I" entry pointso Turntable phono cartridges

o Magnetic heads of tape decks

o Connecting cords between audio equipment

o Primary power supply circuits

o Speaker cords

o Tuner antennas and connecting cords

INTRODUCING... THERoADRUNNER ADMM

FROM WESTON

AUDIO RESPONSE'PLUS DIGITAL DISPLAY

O 5 RANGE AUDIBLE SIGNALING FUNCTION

O RUGGED FIELD SERVICE DESIGN

O 0.5" LCD DISPLAY

O 6 FUNCTIONS

O 29 RANGES

WESTON INSTRUMENTSTHE MEASUREMENT PEOPLE'

614 Frelinghuysen Ave.,Newark, NJ 07114

SANGAMO WESTON

Schlumberger

Circle No. 125 on Reader Inquiry Card ETID - November 1979 / 15

Pioneer

The following Service Seminar items refer to amplifier interfer-ence problems and their proper cure.Induced in the input terminals or connecting wires. Con-nect a capacitor to the chassis and grounding point of inputterminal. The value should be between .01 and .047µF(CKDYF103Z5CKDY473Z50). To ground the rear panel, re-place the original screw with ABA -115 and solder one of thecapacitor leads to it. The length of the capacitor leads shouldbe short as possible.

ABA -115

Induced into the grounding wire of turntable output cord.Add a new grounding point near the GND terminal usingABA -115 screw and connect the terminal to the ABA -115 witha thick lead or braided wire.

Use thick orbraided wire(Give a slackto the wire)

- ABA -115

Rear panel

- GND terminal

Induced in audio signalroutes of the amplifier, suchas preamp stage and controlcircuits. If it is in a differentialamplifier, add a capacitor orreplace Cl and C2 to achieve acapacitance of Cl =C2=47 to100pF. Also replace Rg and Cawith larger value components,but do not exceed 2.2Kohmsand 100pF respectively.

Next Month in ET/D

Modules-Repair or Exchange

Magnavox's "Micro -Tune"

Output Transformerless Amplifiers

More on Microprocessors

ET/D's Annual Index

Rg1 R521.2100 12100

cut 1 CO2156pFI 56pFI

C TREBLE VR

o PU cow

Tone arm

1001-0047,

Head Shield veir

1001-0 04701

R/P amp

2200

1000pF3 OUTPUT

In a conventional amplifier,type 1, add a 47 to 100pFcapacitor to Cl between theemitter and base. Also replaceRg and Ca with larger valuecomponents, but not exceed-ing 2.2Kohms and 100pF.

For a type 2 conventional amp,divide the filter consisting of Rgand Ca into two stages to get asharper effect. The value of theparts should be:Rgl + Rg2 =2.2KohmsCal + Ca2=100pF

If Amp I is entering throughtone control circuits employingB -type VRs (VAX or LUX), in-sert a capacitor across the tre-ble control volume. The valuesshould be 470 to 680pF:100Kohms up to 1000pH:10Kohms.

Induced in phono cartridgeor turntable lead wires. Con-nect the earth lead to theground via the capacitor speci-fied; employ the shortest routefrom the tonearm to the chas-sis. Never connect to the posi-tive lead.

Induced in the tape deck.Connect C, specified headlead wire, to the chassis. Also,replacing the head leads withthe shielded wire is sometimeseffective, if the shielded wire isnot employed. Caution: Neverconnect a capacitor to the sig-nal line.

Induced in the signal line ofthe tuner. Connect a specifiedRC filter to the output terminal.

Induced into the AC line. Insert a line -cross capacitor (C1 orC2) into the AC outlet terminals. An ACG-003 with insulatorcover (AE279) should be used. Caution: Don't let capacitorleads touch others. rro

AC outlet

C.

To power source

C 2

16 / ET/D - November 1979

ET/D's new Modern Serviceshop Management Manual

O Just what you need to keep your business running smoothly and profitably!Filled with ideas and advice on situations faced in owning your ownserviceshop, this manual is perfect in helping you cope with yourday-to-day business problems.CATEGORIES INCLUDED ARE:

5: Business Management4 Chapters on basic accounting procedures, ratio analysis, planning for profit in theO business environment and current asset managementI- Service of Electronics Equipment

Nixst Chapters on troubleshooting transistorized circuits, modern test equipment, digitalE 0 electronics, industrial control systems, and modern serviceshop layoutI- New Business Horizons0 w Chapters on whether to expand your business contract service, business opportuni->-

0 ties in medical electronics and service business opportunities in small industrialZa.0

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ccmi._ Please send me __ _ copy(ies) of MAIL TO:

0LLI wn ET/D's MODERN SERVICESHOP MANAGEMENT ET/D Magazine/Book Dept.

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z MANUAL at $12.95 per copy. (Please add 1 East First St.i-- $1.50 per order to cover postage and handling. Duluth, MN 55802N On multiple copy orders add 25¢ for eachuiI- additional copy.) 13<_i

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Publication Date: Now available! Orders will be fulfilled within 60 days of thedate of order.

ORDER ET/D'S MODERN SERVICESHOP MANAGEMENT MANUAL TODAY!

Please send me copy(ies) of MAIL TO:ET/D's MODERN SERVICESHOP MANAGEMENT ET/D Magazine/Book Dept.MANUAL at $12.95 per copy. (Please add 1 East First St.$1.50 per order to cover postage and handling. Duluth, MN 55802On multiple copy orders add 25¢ for eachadditional copy.) 13

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Filled with ideas and advice on situations faced in owning your ownserviceshop, this manual is perfect in helping you cope with yourday-to-day business problems.

CATEGORIES INCLUDED ARE:

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STRICTLYBunnus

Not everybody is motivated by a money incentive. It is true that in many

cases, men will work harder and smarter when paid a bonus or an

incentive or if working on straight commission ... but not all of them.

Sometimes it is a matter of the man's position in life. If the man is young

and struggling, trying to put food on the table, trying to build a life for

himself and his family, he will really turn on to an incentive program.Other men, though, are in a more comfortable position. They have a

nice place to live, they eat steak about as often as they want to, there are

two cars in the garage and plenty of beer in the refrigerator, and they have

the boat and the outboard for fishing. These men may be a lot more

interested in working conditions than in making more money. They don't

want to work overtime ... they want to go fishing.There are other men who have established in their minds what they

consider a good day's work. Once they reach that level in a day, they slow

down or even come to a dead stop, regardless of the incentive.

Still others may find it psychologically impossible to work under a

commission type of system. They may be buying expensive cars in the

winter, and eating macaroni and cheese in the summer. If the men can

accommodate this, often their wives cannot.There are some additional problems that may be encountered when

installing an incentive system. If, for instance, you weigh the program for

speed, you may well get speed ... but at the expense of quality, or good

customer relations. Or the men may get to bickering over the "good" jobs.

The bottom line on incentives is that they require a great deal of

consideration on the part of the manager. A good incentive program can

be very effective in raising productivity, but take care to avoid the pitfalls.

Make sure your program does not inadvertently reward unwanted

behavior, such as undue speed, bruskness, or "loading" the job.Make sure the program is simple and that the men thoroughly

understand it. Each man should be able to compute his bonus each day.

Make sure you have established standards which the men must meet

and set up a way to measure each man's performance against those

standards.Make sure your program provides adequate income for the technician

in

the months in which productivity is low.Make sure your program considers the effect of days off ... holidays,

sick leave, days spent in training.Make sure that you, as the manager, are in close touch with the men,

guiding them, helping them achieve.Make sure you get the most mileage from the program, through

recognition and awards.And finally, if you would like a free copy of NARDA's four -page brochure

on Incentives for Technicians, just write me at NARDA, 2 N. Riverside

Plaza, Chicago, IL 60606.Incentive plans can increase productivity, sometimes dramatically, but

they require your careful attention.

Mgr., NARDA's Service Divisio

ETID - November 1979 I 19

SatellitetelevisionreceptionForty channels direct

For those remote fromtelevision stations or thosedissatisfied with localreception, direct from satelliteTV may be the answer, thoughan expensive ($5000 up) one.

By Walter H. Schwartz

More than 22,000 miles above theequator, some 30 geostationary(so-called because they revolve onceeach 24 hours, and thus stand stillrelative to the surface of the earth)satellites relay various types ofcommunications back to earth.

These satellites can be spaced about4 degrees (about 1800 mil) apart atpresent, in an orbit about 172,000 milesin circumference. These satellites aremaintained within an area about 70miles on a side by hydrazine rockets,which can be operated to correct for driftin position. The life of a satellite is aboutseven years (it finally runs out ofhydrazine).

The electronic system involved in thistransponder is simple in concept. Solarcell powered, they receive signals fromthe ground over a frequency range ofapproximately 5.9 to 6.4GHz, and thenhetrodyne it with a local oscillator at2.225GHz to transmit an output of 3.7to 4.2GHz

The input is filtered through a bank of40MHz bandwidth filters, goes to themixer and then to a traveling -wave tubeamplifier. The ground stations cantransmit the power required to insuregood reception at the satellite. However,

General Telephone and Electronics' new, low sidelobe, antenna, said to allow spacing ofcommunication satellites within two or three degrees of each other.

the TWT amplifier output is only fivewatts. This, coupled with highlydirectional antennas, results in aneffective radiated power of over 3000watts, directed at the north central U.S.,and a power level about 1 or 2dB less forthe rest of the contiguous 48 states.Alaska and Hawaii receive lower signallevels. The receive path loss, however,is 196dB; the maximum signal to bereceived then is about -1600Bw.

The signal is a bit different than thestandard TV signal we are accustomedto. It is a wideband FM signal with anaudio subcarrier at 6.2MHz or 6.8MHz,

usually; apparently other subcarrierfrequencies are sometimes used. Tofurther complicate matters, the carrieralso is frequency modulated at a lowerdeviation by a 30Hz signal for energydispersal, a process which reducesinterference with ground microwavelinks.

Consequently, the total receivingsystem is more elaborate than anythingwe usually observe in standardtelevision reception (Fig. 5).

AntennasTwo types of antennas are possible

20 / ET/D - November 1979

SATELLITE POSITION NUMBER OFLONGITUDE CHANNELS

SATCOM I 135°W 24

SATCOM II 119°W 24

SATCOM III* 132°W 24

WESTAR I 99°W 12

WESTAR II 123.5°W 12

WESTAR91°W 12

COMSTAR I 128°W 24

COMSTAR II 95°W 24

COMSTAR III 87°W 24

ANIK III 114°W 12

ANIK B 109°W 12

*To be launched October or November '79

** To be launched Aug. '79

Fig. 1 Satellites of interest for TV relay.

Fig. 3 Paraframe R & D's laminatedframework dish with rotatable feed hornfor polarization change.

PARABOLICREFLECTOR

LOW LOSSCOAXIAL CABLE

COLLECTOR HORNAND LOW NOISEAMPLIFIER (SI

Fig. 5 Satellite TV reception system.

WESTAR SATCOM CENTERAND ANIK FREQUENCY (GHZ)

CENTER HORIZ VERT.FREQUENCY(GHZ)

3.720 3.740 3.720

3.760 3.780 3.760

3.800 3.820 3.800

3.840 3.860 3.840

3.880 3.900 3.880

3.920 3.940 3.920

3.960 3.980 3.960

4.000 4.020 4.000

4.040 4.000 4.040

4.080 4.100 4.080

4.120 4.140 4.120

4.160 4.180 4.160

RCA (SATCOM) gets twice as manychannels (24 instead of 12) byoverlapping adjacent channels andstaggering horizontal and verticalpolarization.

Fig. 2 Satellite down frequencies.

Fig. 4 The United States Tower Company'sfour meter dish. Fiberglass over aluminum.

candidates for use in satellite reception.Horns and parabolic reflectors can beused; phased co -linear or yagi arrayshave too much loss in theinterconnecting harness.

A parabolic reflector about eight feetin diameter would appear to be justabout the absolute minimum sizeusuable. Diameters of less than eightfeet not only have less gain, but thebeam width widens, and especially asyou get farther north and east and beginlooking closer to the ground, as theangle of the satellite above the horizondecreases the more noise your pick up

RF MODULATOR

TR RECEIVER OR

VIDEO MONITOR

from the hot earth. The larger reflectorsprovide a narrower beam pattern, andmore gain makes reduced demands onthe system following. It has to bedecided whether to spend the money onantenna size or low -noise preamplifiers.Practically 10, 12 and 15 foot reflectorsseem to be popular, Fig. 3, 4, 6.

At far north latitudes, where theantenna angle is very low, reportedlyhorns are used, since the mouth doesnot have to be elevated appreciablythere and the horn is more free of sidelobes that potentially would pick upterrestrial noise. The horn could be

interesting, since it has no curves.Construction of its framework couldpossibly be a carpentry job, since it is thesize of a small building. (If you want todesign a horn, see Henry Jasik ed.Antenna Engineering Handbook.)

The signal is focused by the parabolicreflector into a feed horn mounted,obviously, at the parabolic focus point.(Fig. 7.)

LNA'sMounted at the feed horn, to avoidcoaxial cable losses, are usually one ormore preamplifiers known aslow -noise -amplifiers, LNAs. These arecostly lithe items of hardware, but thesignal available at any practical antennarequires the use of an amplifier forusable reception. The noise figure of theLNA is extremely important. The largerthe antenna, the poorer the noise figurethat can be tolerated. For example,according to Dexcel, their ModelSXA-3091-01 (33dB minimum gain,1.8dB noise figure) will produce superiorreception with a 12 foot dish andadequate reception with a 10 foot dish inmost North American locations. Theselow noise amplifiers are usually builtright on the wave guide for mounting tothe feed horn (Fig. 9).

The receiverWe are not speaking here of your TVreceiver. The signal needs specialprocessing before you can feed it to astandard TV set.

A typical receiver, Avcom's PSR-3, isa wide band double superhetrodyne FMdemodulator (Fig. 10). The output isvideo which can be viewed on a videomonitor or modified TV set, or fed to aremodulator for input to the antennaterminals of an unmodified TV set.

The first local oscillator is voltagetuned at a sub -multiple of theapproximately 2.8GHz to 3.3GHzinjection frequency. A step recoverydiode multiplier, multiplies the frequencyinto the proper range resulting in a first IFfrequency of 880MHz. A 950MHzoscillator in turn hetrodynes the signal toa second IF of 70MHz. The 70MHzsignal is amplified, limited anddemodulated. The resulting video isclamped to remove the 30Hz energydispersal modulation, and amplified to alevel suitable for a video monitor.

The audio subcarrier demodulatorcan be tuned to either the 6.2MHz or6.8MHz subcarriers and the receiverhas audio output to drive an externalspeaker. An optional subcarrierdemodulator can be connected to theinput of an FM stereo receiver and

ETID - November 1979 l 21

Fig. 6 Dalsat uses an Andrews dish withthe feed horn and wave guide rotatablefrom its base.

Fig. 8 Four Dexcel LNA's. Each has 33dB,minimum gain.

provides reception of the stereotransmissions from the satellitessimply by properly tuning the FMreceiver.

The PSR-3 voltage controlled firstoscillator can sweep its range toscan -tune the entire 3.7GHz to 4.2GHzband. This is most useful during antennasetup.

So there you are. A parabolic antennacosting, including mounting, concretework, etc., perhaps as little as a coupleof thousand dollars. A low noisepreamplifier (LNA) costs from onethousand dollars up. The receiver pricesseem to begin at about two thousand.The minimum costs of commercialequipment would be about $6000 at thistime. Advances in semiconductors forthe LNA's and in manufacturingtechniques for low priced antennas maymake significant cost reductionspossible, however.

The legal situation is in flux. The FCCis due to clarify the situation shortly,however. The transmissions are all bycommon carrier; you are supposed topay for the service. For example,Channel 17 from Atlanta is open toanyone for a payment of $60/yr;C -SPAN, the new sports service whichwas to have begun September 1, isreportedly available for a single one timepayment of $2.40. The movie channels,HBO, Showtime, etc., have a standard

Fig. 7 The rotatable feed horn assembly ofthe Para frame R & D antenna.

Fig. 9 A rotatable feed horn and an LNA atits base.

Fig. 10 Avcom of Virginia's PSR-3 satellitevideo receiver.

rate; but they seem to be ignoring hometerminals at this time. Three religiouschannels and the live Congressionalsessions are reportedly free.

Sources of Information andEquipment

GENERAL INFORMATION:

SATELLITE TELEVISIONTECHNOLOGYP.O. Box GArcadia, OK 73007Publications covering background,licensing, as well as several workingsystems are available. Also informationon program material.

SATELLITE INNOVATIONSP.O. Box 5673Winston Salem, NC 27103Polar mount and feed horn rotationinformation package, $10.

ANTENNAS:

PARAFRAME R&DP.O. Box 423Monee, IL 60449

VSCPO Box 582Guin, AL 35563

UNITED STATES TOWER COMPANYP.O. Drawer "S"Afton, OK 74331

LOW NOISE AMPLIFIERS:

SCIENTIFIC COMMUNICATIONS,INC.3425 Kingsley RoadGarland, TX 75041

DEXCEL, INC.2285C Martin Ave.Santa Clara, CA 95050

RECEIVERS:

AVCOM OF VIRGINIA, INC.SATELLITE SYSTEMS DIV.10139 Apache RoadRichmond, VA 23235

SCIENTIFICCOMMUNICATIONS INC.3425 Kingsley RoadGarland, TX 75041

INTERNATIONAL CRYSTALMFG. CO., INC.10 North LeeOklahoma City, OK 73102

MICROCOMM14908 Sandy LaneSan Jose, CA 95124

COMPLETE SYSTEMS:

STARSCANTwo Post Oak Central1980 S. Post Oak Road, 20thFloorHouston, TX 77056

DALSATP.O. Box 1960Plano, TX 75074

HOMESATA Scientific Atlanta SubsidiaryP.O. Box 13654Atlanta, GA 30324 ETD

22 / ET/D - November 1979

This is an offer you shouldn't resist. Tointroduce you to the new family of oscil-loscopes from B&K-PRECISION, we'lllet you "live with" one for up to 10 days,free! We're confident that after tryingany one of our new scopes, you'll wantto keep it for a lot longer. Of course,there's no obligation.

Leading off our 1400 series scopes isthe new 1479, 30MHz dual -tracetriggered scope. It's ready to challengeyour testing needs with 5 mV/cm verticalsensitivity, 11.7 nS rise time, 50MHztriggering and built in high- and low-passfilters. A signal -delay line is built in topermit view of the leading edge of highfrequency pulses. The 1479 also providesdifferential input capability and algebraicaddition and subtraction of input signals.

For those requiring only a 15MHzdual -trace scope, the 1477 is an outstand-ing solution. Having many of the fea-tures of the 1479, the 1477 also offers a

standard video sync separator for usewith video systems or computer termi-nals. If battery portability is essential,the B&K-PRECISION 15MHz 1432 is afield -proven workhorse. It's a fullfeatured 3", dual -trace scope with anoptional battery pack. For a 10MHz re -

Model 1405 $255 tiModel 1432 $840

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sponse, choose either the dual -trace 1476or the single -trace 1466. With video syncseparators and vectorscope capability,both are standouts. For basic monitoringapplications, the low cost 5"1405 is thebest answer.

Common features of all 5"1400 seriesscope include Z-axis inputs, plug-in PCboard construction, scope camera -compatible CRT bezels, triggered sweep,excellent high- and low -voltage powersupply regulation, built in calibrationsignals and cool, energy -efficient opera-tion. The 1466 draws 20 watts; the 1479draws only 25 watts.

For immediate delivery on the scopeof your choice or for additionalinformation, contact your localB&K- PRECISION distributor.

DYNASCANCORPORATION

6460 W. Cortland Street Chicago, IL 60635 312,889-9087

In Canada Atlas ElectronicS Ontario International Sales Emo,re Exporters inc.270 Newtown Road, Plainview. L.I., N.Y. 11E100

Before you look at another scope,try one of these free for 10 days!

Model 1477 $840 Model 1479 $1099Model 1476 $655

Circle No. 106 on Reader Inquiry Card ET/D - November 1979 I 23

Microprocessorsfrom A to ZDoing it the easy way

ET/D begins a series forpeople who want to know whata microprocessor is, how itworks, and how to use it. It is a"stand alone" course with allterms defined and no previouscomputer technologyknowledge required.

By Bernard B. Daien

This series provides an easy entry to theworld of microprocessors by stressingconcepts, instead of details. Thesearticles can be quickly read by thosewho understand basic electronics, butnot digital electronics.

Upon completion, the reader shouldbe capable of understanding the tradeliterature covering the installation, use,troubleshooting, and programming ofmicroprocessors.

Microprocessors' growthAlthough microprocessors (MPUs) areusually viewed as "computers," thecomputing function is only a portion ofthe MPUs applications, since it is wellsuited for data processing and controlleruses. "Data processing" includes, but isnot limited to, the gathering, analyzing,sorting, organizing, arranging, anddistributing of data. To do this, data mayhave to be stored, retrieved fromstorage, displayed, printed out, oraltered, as needed. The data may beused in computation, but as you can nowappreciate, the computation would onlybe a small part of the data processing.

For example: customer lists are firstsorted alphabetically, then placed onpunch cards, which are used later forbilling, mailing lists, or other uses. The

Fig. 1-A sophisticated, programmable microprocessor is the heart of this advanced heatpump control system from Honeywell's Residential Controls Center. Transducers encodeindoor, outdoor and wall temperatures in home or office buildings for computerizedcontrol of indoor air flows.

customer list might also be placed onmagnetic tape for storage, encoded indigital form. 'The term "digital" will beexplained later.) The MPU would beused to encode and decode theinformation, and use it to performdesired tasks in accordance with theinstructions given to the MPU in the formof a "program" written by a programmer.

This handling of digital data is a verylarge and important use of MPUs. Datatransmission over telephone and othercommunication systems is now a hugebusiness, and growing faster than anyother type of communication. Bankscommunicate about credit cards andaccounts. Stock markets reports andother business transactions are

included in data transmissions.In some cases, large computers are

required because of the amount of datato be handled, and the speed required,but there are many situations in which asmaller, slower, and less expensivemachine (the MPU) is adequate.

Because of the tremendous amount ofdata being handled every day, manualhandling is far too slow and error proneto suit our modern society. The MPU canbe utilized to perform thousands ofoperations per second, involvingdifferent types of data, performing manydifferent operations, and is faster than allother methods of data processing,excepting only a larger, more expensive,general purpose computer.

24 / ET/D - November 1979

MPUs also are used extensively in"process control." In this case the MPUacts as a "controller," achieving desiredconditions and results, by controllingmachines in accordance withprogrammed instructions. Someautomobiles now have MPUs whichcontrol the mixture of gasoline and air soas to achieve complete combustion.These MPUs take into account suchvariables as altitude, air temperature,barometric pressure variations due toweather, and engine loading. In the past,controllers were devised usingcombinations of mechanical, electrical,hydraulic, and pneumatic systems. Butthe MPU is faster, more accurate,smaller, lighter, cheaper, and it isprogrammable. It is therefore veryflexible, and can be used in a wide

Fig. 2 -An example of types of test gear fieldservice technicians of the future will beworking with is this portable, microprocessorcontrolled diagnostic tool. For use introubleshooting Honeywell's heat pumpcontrol system, the field technician simplyconnects to the unit under test and automatic"error" messages display location and typeof trouble.

variety of applications, which results inlarge sales, which further reduces theprice due to mass production. This is amain reason for the MPUs' success ...wide applicability, mass production, lowprice, due directly to itsprogrammability.

The MPU invasionIn many cases the MPU is a built-inunrecognizable part of the equipment itcontrols. Using data from the equipmentitself, and instructions from humans, anddrawing upon its memory banks, theMPU makes fast, accurate, complexdecisions, which control the hostequipment in a very versatile manner.The MPU is being used more and more

to control machinery, and again the word"speed" crops up.

Of course it isn't practical to use a$500,000 computer to control a $50,000machine in most cases. The MPU withits lower cost makes practical the use ofdigital control for medium, and evensmall sized, business.

The MPU can be programmed, andreadily reprogrammed, to do manydifferent tasks. Thus, one MPU can bemany things for many people, like amagic circuit board, which changes itsfunctions in accordance with the wishesof the operator! An MPU can bepurchased, secure in the knowledge thatit will not be rendered useless by somechange required in the manufacturedproduct.

So ... if you think about it, we aresaying that MPUs use programming toreplace hardware. By changing theprogrammed instructions, the MPU canbe made to perform a new and differenttask, without the necessity of purchasingnew equipment. And that is the secret of

success of the MPU.

What a microprocessor isMPUs have been defined many differentways, which often confuses readers ofmost microprocessor texts. Usually thediscussion concerns computers, andthen the MPU is defined as "part of acomputer." We will attempt to define theMPU in simpler terms.

Modern MPUs are large scaleintegrated circuits (LSIC), containing8,000 -to -10,000 transistors which canbe used to replace many different typesof integrated circuits, by imitating theirfunctions. The MPU is fed an input,called "data," and instructions telling itwhat to do with the data. It is theinstruction that tells the MPU what typeof circuit it must emulate.

The term "large scale integratedcircuit" indicates the size and complexityof the integrated circuit. An IC whichreplaces a single stage of an amplifier, isconsidered "small scale." If it replacesan entire sub -section, such as the entiresound amplifier, or color section, in a TVset, it would be regarded as "mediumscale." Larger ICs with thousands oftransistors are "large scale." Today wehave "very large scale" ICs, withhundreds of thousands of transistors,and the end is not in sight!

Let's be specific. Suppose we want anMPU to add some numbers. Thenumbers to be added are the "data." Aninstruction, "add" indicates what wewant to do with the data. In this case, theMPU is performing the function of anadder.

The MPU can perform a very widevariety of functions, some requiring anentire series of steps to complete. TheMPU can perform several functions, insequence, in order to accomplish agiven task. This requires a series ofinstructions, called a "program." Sincewe wish to enter the program into theMPU all at once, we need some"memory" circuits, which can accept theentire program of instructions, and thenimplement it, step by step, in thenecessary sequence. This establishesthe fact that the MPU IC, by itself, is verylimited in usefulness. Some memorycircuitry is required to "support" theMPU. Other "supporting" circuitry alsoincludes input and output "interfacedevices. Interface devices are not newto you. A hi-fi amplifier often uses amatching transformer to interfacebetween the amplifier and the speakers,for example. MPUs often communicatewith the user over the telephone, inwhich case the interface device wouldbe a telephone coupler.

Interfacing can be defined as theprocess of connecting different circuitstogether in such a way that they operatein a coordinated manner. When weinterface "input" or "output" devices,we abbreviate them to "I/O devices."

Let's get some feeling for howcomplex the MPU IC is. Relating to whatyou are familiar with, the MPU is morecomplex than the student type electronicpocket calculators, which can performonly the functions indicated on thekeyboard. The MPU remember, can beprogrammed for a wide variety of tasks.

On the other hand the MPU is lesscomplex than the larger general purposecomputers, because the MPU by itselfcannot do very much. It requires supportcircuitry consisting of a power supply,interface devices, memory circuitry, acontrol panel, some kind of readout, etc.The general purpose computer has all ofthese things within its cabinet.

Before the advent of the MPU, logiccircuits were constructed on printedcircuit boards to perform specificfunctions. If the function had to bechanged, the circuitry had to be rebuilt,with loss of time, labor, and money. Withthe MPU, a library of programs permitsfrequent, quick, task changes.

Hardware vs. softwareIt is important to understand thatprograms do not materialize out of theair! They are costly. A programmerneeds skill, time, and equipment to writea program of instructions. The programmust be run on equipment similar to theMPU it is to be used with, in order to

ET/D - November 1979 125

Fig. 3 -Leader Instruments Corporation's "computerized" 5800 production testoscilloscope system is perhaps typical of the types of sophisticated production controlunits soon to be common. This system permits anyone who can use an oscilloscope toselect up to 32 preset configurations for the viewing of waveforms at up to eightpreselected test points.

detect any errors in the program.Eliminating all of the errors requiresrunning, and rerunning, and correcting,and recorrecting the program. This iscalled "debugging," and may takeweeks, depending on the length andcomplexity of the program. We arestating that we have exchanged one setof problems for another set of problems.In the language of computers, we havetraded "hardware" for "software."Hardware is defined as actual physicalapparatus including electrical, electronicand mechanical parts. "Software" isdefined as programs and instructions,on paper. Sometime the MPU andsoftware can be used to replacehardware with economic advantages. Attimes the reverse is true. Eachapplication must be examined todetermine the most cost effectiveapproach.

Microprocessors vsmicrocomputersThe MPU alone is not a self sufficientdevice. It needs much support circuitryto perform most tasks. If we add therequired circuitry ... power supplies,memory, I/O to interface devices, etc.,we can perform computing tasks, and atthat point we have expanded our MPUinto a minimal computer ... a"microcomputer." This small computeris not as fast, and not as flexible as alarge computer. It can only do oneoperation at a time, step by step, inaccordance with the program. Mosttasks take the MPU through many steps,requiring milliseconds to accomplish. Alarge computer would do the same taskin a few microseconds, thusaccomplishing more work per second.This ability to do work fast is called"computing power," therefore MPUs are

not considered to be very powerfulcomputers. They are adequate wheregreat speed and flexibility are notparamount.

MPUs are also limited in the amount ofmemory capacity that can be controlled.Great strides are currently being madein MPU design, and the new MPUs areas powerful as some of the largercomputers of a few years ago ... but ... inthe meantime, the larger computershave also grown more powerful, so thatthe gap still remains when comparingthe performance of an MPU with a largecomputer.

A large bank needs a large computerto handle the thousands of transactionsoccurring daily, and recording andstoring enormous amounts of data inmemory. A small factory, on the otherhand, might only require an MPU withappropriate supporting hardware tocontrol a production machine. Thedifference in cost between the twosystems would be large. As a matter offact, the MPU would cost so little, thatthe cost of the software programsrequired would probably be greater thanthe hardware costs!

The MPU and youBy now you should be starting tounderstand the implications of the MPUand the new industry it has created.People are needed to build MPUs, sellMPUs, install MPUs, maintain MPUs,and program MPUs. Other people areneeded to build the required supporthardware ... power supplies, keyboards,cabinets, semiconductors, etc.

Technicians who understand themicroprocessor (MPU), can take theirpick of jobs offered in all the tradeperiodicals. There is an optimum time toenter each new technology. For

example, five years ago a TV technicianwho understood vacuum tubes could getalong nicely, but today a TV technicianneeds to know both vacuum tube andsolid state to service the existing sets. Inanother five years a tech will only needto know solid state. Most of the tube typesets will have worn out. Anotherexample: A tech working in a factorymaking auto radios would have had tolearn about solid state when technologymandated a fast changeover totransistor auto radios. If he did studysolid state in the 1950's, he had only tolearn about the bipolar transistor, andthen, when JFETs, MOSFETs,Darlingtons, integrated circuits, etc.,came along, they were learned easily,one at a time. The tech who delayedgetting into solid state, had to learn allthe devices at once, a much moredifficult task. So there is an optimumtime to "get into" a new technology, andit is now.

It has been said that a programmerreally does not need to know what isinside the MPU in order to write aprogram. This is only partially true. Theprogrammer who understands how theMPU works, however, can generallygenerate shorter, more conciseprograms than the programmer whomerely follows certain rules, withoutknowing why. You will certainly beworking with apparatus that uses, orinterfaces with, MPUs. You will benefitfrom the knowledge about how the MPUworks. This fact has not escaped thenotice of most employers, and there isnow arising a good demand foremployees who understand the MPU.

There are several well knowncompanies now manufacturing MPUs,and others are still entering the race, asthe market grows. Each brand has itsadvantages, and disadvantages. Somehave more internal memory, othersmore speed, others more flexibility ofapplication. There is still no realstandardization in many areas ...therefore you cannot replace one MPUwith another in most cases. Certainbrands have arranged for othermanufacturers to build the same deviceso as to have a "second source," whichmost customers require.

Some brands have a wide variety ofsupport hardware available, whileothers do not. There is no hard and fastrule. This series of articles has beenwritten to enable you to deal with most ofthe popular MPUs now on the market.

FirmwareYou already know the terms hardwareand software ... there is a third termcoming into popular use, "firmware."

26 / ETID - November 1979

Firmware, as you might guess, issomewhere between hardware andsoftware. Hardware is by its very nature,quite permanent. Software can be easilychanged. Firmware consists of memorythat can not be readily changed by theuser, such as a permanent memory IC.Such devices are called "Read OnlyMemories" (ROMs), because, like abook, once written they can be read overand over again without changing thecontents of the book. It is not possible toadd, delete, or change informationstored in a ROM. The information isunchanged by use.

ROMs can be purchased alreadyprogrammed with the desiredinformation, ready to plug into an MPUsystem. Other ROMs can beprogrammed by the user, or by the localdistributor, and these are called"Programmable Read Only Memories"(PROMS). We will discuss memoriesfurther, later on, but for now it is onlynecessary to know that it is possible tobuy memories large enough to storemore information than most MPU userswill need. These add-on memories havealready enabled the MPU to competewith larger machines in some areaswhich were formerly the sole domain ofthe large computer. This accounts, inpart, for the growth of the MPU market.

As MPU costs drop it becomesfeasible to use them in moreapplications. Today they are being usedin food mixers, microwave ovens, andwashing machines. They are used inautomobiles to control air gas mix inorder to prevent pollution, which is a loteasier than trying to clean up pollution.(An advantage is better performanceand fuel economy.) Perhaps one of thelargest factors limiting faster MPUgrowth is the lack of personnel trained touse the MPU. The MPU is a hightechnology device, and skilledpersonnel are required for thistechnology. By reading the followingarticles in this series, you will gradually,and easily, move into this technology.

SummaryIn this article you learned what an MPUis, and what it does. You also acquiredsome "buzz words," the workinglanguage of the MPU technician, tradedefinitions. More than this, you havenow an insight into the implications ofthe MPU, the factors responsible for itsrapid growth, and how the MPU isaffecting you and your occupation. Thislays the groundwork for the morespecific articles to follow, covering thedifferent parts of the MPU, and how theycoordinate with each other. ETD

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So visit your dealer today and get your hands on the DMM that does itall. Or call (714) 871-4848, ext. 3651 for your nearest distributor.

BECKMANCircle No. 107 on Reader Inquiry Card

ETID - November 1979 / 27

Intro to digitalelectronicspart VIIPutting it all together

In his seventh and finalinstallment, Mr. Carrdescribes the theory andoperation of the most commondigital counting circuitconfigurations.

By Joseph J. Carr, CET

A digital counter is a device or circuit thatoperates as a frequency divider. Themost basic form of digital counter is theJK flip-flop connected with the J and Ktied HIGH. This makes the outputproduce one output pulse for every twoinput pulses. It is, then, a binary, ordivide -by -two counter.

ET/D readers are familiar with digitalfrequency counters. These are simplytest instruments that are used tomeasure frequency. Those instrumentscontain decade counters (i.e.divide -by -10).

There are two basic classes of digitalcounter circuits, serial and parallel. Theserial counters are called ripplecounters because a change in the inputmust ripple through all stages of thecounter to its proper point. Parallelcounters are called synchronouscounters.

In a ripple counter, the data istransferred serially, which means thatthe output of one stage becomes theinput of the following stage.

The basic element in most counters isthe J -K flip-flop (Fig. 1A). Note in thefigure that the J and K inputs are tiedHIGH, so they will remain active.

A timing diagram for this divide by twocircuit is shown in Fig. 1B, and it shows

the action of the circuit. J -K outputschange state on negative -goingtransitions of the clock pulse. In Fig. 1B,the first negative -going transitioncauses the Q output to go HIGH. Q willremain HIGH until the input seesanother negative -going clock pulse. Atthat time the output will drop LOW. Theaction required to make a completeoutput pulse requires two clock pulses,so this J -K flip-flop is dividing the inputfrequency by two.

We can make a binary ripple counterby cascading two or more stages, asshown in Fig 2A. This particular circuituses four J -K FFs in cascade. Anynumber, however, could be used.

The major problem with this type ofcounter is that only those division ratiosthat are powers of two can beaccommodated. In the four stage circuitshown, the possible division ratios are 2,4, 8 or 16.

Frequency division is one major usefor a counter circuit. In some electronicinstruments, for example, we may wantto prescale a frequency, i.e. divide itfrom some higher frequency to a lowerfrequency that can be handled by adigital counter or other instrument.

But this is only one application for thecounter circuit. One of the mostcommon applications, alluded to in thelast paragraph, is to count, i.e. tell us thetotal number of pulses that passed.Consider again the circuit of Fig. 2A, andthe timing diagram of Fig. 2B. Outputs A,B, C and D are coded in binary, with Abeing the least significant bit and Dbeing the most significant bit. These areweighted in a 1-2-4-8 code system torepresent decimal, or hexadecimal,digits 0-15. These are the normalweights of the binary number system.

+5

A

Input

BP

Fig. 1 The J -K flip flop is the basic element inmost counters. Figure 1B is the timingdiagram for the circuit illustrated in 1A.

Consider the timing diagram of Fig.2B. Note that all Q output changes occurfollowing the arrival of each pulse. Afterpulse number one has passed, the QAline is HIGH and all others are LOW.This means that the binary word on theoutput lines is 00012 (i.e. 110); one pulsehas passed.

Following pulse no. 2 we would expect00102 (i.e. 2,0) because two pulses havepassed. Note that C)B is HIGH and allothers are LOW. The digital word is,indeed, 00102. If you follow each pulse,you will find the binary code to be asshown in Table I.

The counter shown in Fig. 2A could becalled a "modulo -16" counter, a"base -16" counter, or a "hexadecimal"counter. (All meaning the same thing.)

The output of a hexadecimal countercan be decoded to drive a display device

28 / ET/D - November 1979

F 2

A B

F.4

FF2 FF3

Note All J -K terminals are tied high

A

Fi8

C

FF4

F'16

0

CLOCK

A 1

8 2

C 4

B 08

21 3 sl 1617 8 191 10 11

I

Fig. 2 Cascading four J -K flip flops as in 2A produces this divide by 16 counter, the timing diagram of which is shown in 2B.

aclock0 C FF1

clr-a --

clear

0

C FF2

clr

8

20

0

C FF3

clr

Ti0

o clock 17

C FF4

clr

A

preset

Fig. 4 The basic diagram for a parallel counter -four flip-flops plustwo NAND gates.

to otherstages

Fig. 5 Two stages of a preset counter using "jam input.

indicate 00012. This counter, then,counts in the sequence

0-1-2-3-4-5-6-7-8-9-0-1 . . . The outputcode is a ten digit version of four -bitbinary (hex), and is called binary codeddecimal (BCD).

Synchronous countersRipple counters suffer from one majorproblem: speed. The counter elementsare wired in cascade, so an input pulsemust ripple through the entire chainbefore it affects the output. Asynchronous counter feeds the clockinputs of all flip-flops in parallel