Thesizeoftheresistivetrackdeadbandisparticularly criticaliftheapplication requires thewipers to traveloverthedeadband duringnormal operation. Itisimportant thatthesizeofthedeadband isa minimum of3timesbiggerthanthelengthofthewearpatchonthewiperfingers atendoflife.This margin willaccount forwiperwearratevariability, deadband geometry consistency, wiperpreload variation, andtemperature effects, etc.Although thesizeofthewiperwearpatchwillvaryineach configuration andapplication, thewearpatchlengthinthisapplication wasfoundtogrowfrom0.025mm (0.001 inch)atbeginning oflifeto0.35mm(0.014inch)(Figure 10)atendoflifeafter1,825,000 revolutions (=1.75diameter track).Thesizeofthewearpatchatendoflifewasconsistent overmultiple lifetests.Thelargerdeadband wasalsofoundtobemuchmoreproducible andconsistent intermsof fabrication. Related tothedeadband shorting issue,itwasdetermined thatisalsogoodpractice toutilizeacurrent limitedpowersource whentesting potentiometers toprotecttheunitsfromdamage duetoinadvertent mis-wiring. Thislessonlearned extends tothedesignofactualspacecraft electronics also. Because ofthedelicate natureofthewipersandtherelatively lowwiperpreload, greatcarehastobe takenintermsofhandling andcleanliness ofpotentiometers. Itisrecommended thatthepotentiometers behandled likebearings intermsofcleanliness requirements untilcontained insideaunitorcovered. Special shipping precautions mustbetakenwiththewiperassemblies toensure thatthedelicate wipers donotgetdamaged simplyduetotheshipping process. Although wiperpreload wasfoundtohavearatherwideacceptable rangeforsuccessful performance, it isstillimportant tomeasure/inspect thewiperpreload accurately bothatthevendor andpriorto installation intoaunit.Without adequate dimensional inspection ofthewiperpreload, performance canbe affected inanextreme situation wherethepreload isverylow. Despite allthedesign issues encountered withrotarypotentiometer asdiscussed herein, theunits performed exceptionally inbothqualification testing, lifetesting, acceptance testingandultimately on-orbit overaratherlargetemperature range. Theunitsproved tobeveryphysically robust andnever encountered anyissuesassociated withstructural loading orvibration testing. Inaddition tothedata presented herein,aconsiderable amount oftestdatawasamassed forvarious lifetestsandover20flight unitswhichsupports theuseofpotentiometers forthistypeofapplication. Whenthedesignandhandling precautions recommended hereinareinstituted, theserotarypotentiometers yieldverylinearand repeatable positional output. Rotarypotentiometers havebeenutilized successfully fordecades asthetelemetry deviceforprecision rotaryactuators. Whilepotentiometers arerathersimpledevices, therearemanybasicdesignparameters tobeconsidered asdiscussed herein,Greatcareshouldbetakenwhenoperating potentiometers incold environments andinlonglifeapplications. However, rotarypotentiometers arestillarelatively low-cost, lightweight telemetry optionthatyieldsaccurate andrepeatable resultsevenoverextreme environments, andtheyshouldstillbeconsidered aviableoptionasatelemetry deviceinfutureprecision actuators. References 1.Conley, PeterL.,SpaceVehicle Mechanisms, 1998. 2.Pitney,Kenneth E.,NeyContact Manual, TheJ.M.NeyCompany, Bloomfield, Connecticut, 1973 177