a loec ni ue George M Myers FIGURE 1 FRE1/EAIFY M 5 kI M9 Cc new narrow-band RC receivers respond transmitted signal somewhat like figure showsexcept real-world hardware doesnt have such sharp square cutoffs z limits RC stands exact legal frequency RC transmitter CC stands frequency Common Canier transmitter Join us month find Out about new RC gear really worksand what difference between familiar AM systems new FM ones AM OFF- NO TRANSMISSION euRSTS o- 72CXJ MN FM FIGURE 2 V L IFT lb 2Xx5 MHj examined what transmissions two RC transmitters looked like oscilloscope youd see something like RC systems send out bursts information AM system top does turning transmitter Off precise intervais FM system lower does abruptly shifting its transmission frequency small amount approximately 005 MHz shown receiver sees operations its decoder translates signals useful informationit tells servos what position move NEW advent new RC frequen cies has added just bunch new frequencies us fly onthe FCC regu lations also allow us use new method radio transmission FM past RC sets have used either CW carrier wave signals switched Off mainly back early days singlechannel rudder-only rubberband-powered escapement systems AM amplitude modulation AM familiar practically everyone worldits what radio stations used until fairly recent times now entertainment radio stations using FM frequency modulation transmission lets us have true high-fidelity sound resistant static Now know cant listen FM radio station AM radio vice versa right thats true same situation must occur FM AM RC gear right Wrong such strange situation going take close look month What going talk about Will AM transmitters fly FM receivers vice versa think very timely question Im addressing direct result letter read ers David Shema AMA 5180 lives Bozeman MT Last month bought new JR Century VII Helicopter radio FM system RC42 ck would have first day new JR field another flier showed up Futaba FP-7GK RC42 AM set Since first far FM set club being curious tried following experiment 1 Turned ON FM transmitter AM receiver Result solid con trol over planethe servo func tions moved around solid controlno glitches no jit ter 2 Turned everything OFF Turned AM transmitter FM receiver Result he solid control over Heliboy 3 Later day flying about 200 feet away turned receiver still solid control Heliboy ground well airplane air 4 When flying done went over house look trans mitter signals oscilloscope 38 Model Aviation hi1416H LOW 0 Iu 0 Sure enough clearly FM typical AM question normal must compliment Mr Shema sys tematically checking through new situa tion keep saying people should make tests what observe few actually Its gratifying meet does emphatic point want make results Mr Shema obtained en tirely normal Commercial AM FM broadcast radios free mutual interference two reasons operate different radio frequencies RF 1 AM 055 thru 160 MHz 2 FM 88 thru 108 MHz 2 use different intermediate frequencies IF 1 AM uses 455 MHz 2 FM uses 107 MHz RC AM FM transmissions same RC channel will interfere another because will using same RE will 50 new channels authorized RC model aircraft Both will also using 455 MHz IF except rare dualconversion sets use 107 MHz well An unthinking few have suggested us ing old RC crystals new FM RC sys tems idea both illegal foolish reason worked hard get away old 7208 etc chan nels because overrun interference FM Both AM FM RC signals really two-valued signals system works varying transmitted signal between RC channel frequency 'something else FM case something else frequency three five kHz above below RC channels crystal-controlled stable frequency very small change AM case shift big y zero Hz same DC OFF see Fig 1 RC narrow-band FM RCnbFM really isnt frequency modulation classic communications sense Its modulation mode Frequency-Shift Keying FSK means deviates steps abruptly frequency other rather swinging more-or-less smoothly within limits deviation range 5 kHz RC would case responding voice music have digital computer tele phone modem know uses FSK putting data telephone line through modem should easy understand RCnbFM really uses digital signal form though infor mation carried analog way length time information-pulse ON represents position control stick/knob/lever RC Narrow-band AM RCnbAM isnt SERVOSRVOSERVOSERVO IZ3 FIGURE servos BC system fed diet voltage pulses receiver/decoder servo knows what position has string pulses uses width pulse detemilne position has commanded assume M1E AM AND FM II LIMITERII CIRCUIT Li FIGURE 4 II FM aty An FM receiver has circuit called iimiterit strips off AM-type characteristics signal received before processing signal further AM ThANSMISSION bI/&H VOL 73 FIGURE 5 RA4//v7 TT OFF Loul 4/01-75 FAI TRAAISM 155/OAf OUflU ALWAYS /116A/ 72cXc 7OC5PASS 5AAAD FM NOT CEWTEED 7 xxx 72 7205 iRA NSfr7/T7R 04 RdDUCC3 ADROL PUL ~-5 J FM Pobuc65 Ce~u7ROL PULSES Believe new narrow-band RC systems possible FM transmitter interfere control AM receivr AM transmitter interfere control FM receiver figure alone may tell too muchbut George has very good description what happening months column Read heed amplitude modulation classic commu nications sense either Commercial AM ra dio stations avoid 100% modulation swing ing RE amplitude zero because distorts message causes spatter lets signal appear other places RE band isnt wanted RCnbAM systems switch transmitters crystal-controlled oscillator ON/OFF send control information Information carried analog based length time pulse ON explained before bothered kind distortion Continued page 126 February 1984 39 SAL TFORKII District 3 Symposium Workshop Jan 14-15 1984Sponsored Tusco RC Club Admission $500 y $800 ys Wives Free P-38IBrown Continued oaoe 123 Surface movements should approxi mately follows rudders 3/s-in both ways ailerons /4-in both ways elevator 5/6-in both wayswith little bit uptrim start Aileron response posi tive like full-size aircraft roll rate slow Ailerons rudders needed no trim adjustments elevator model needed bit up-trim offset nose-heaviness Landings Cub-like need full throttle first flight make few landing approaches well before fuel runs low get feel sink rate Dont try come final nose too high keep level down slightly until just before touchdown flair slightly have done some low-speed testing model altitude course hangs stalling surprisingly well youve always wanted try twin boxy add-an-engine designs turn off try racy P-38 Theres nothing like twinon ground especially air Radio Technique/Myers Continued aoe 39 would confuse voice music RC systems designers very concerned spatter however dont actually use ON/OFF switching Instead use shaped tran sition ON OFF ON minimizes spatter Just make things bit complex significant deviations ideal performance hardware both sys tems As consequence ON/OFF signalshaping mentioned above AM trans mitter puts little frequency shift transmitted RF signal time turns signal ON OFF shift FM its minor amount its needed control spatter shift decoded narrow-band FM receiver because re ceiver designed detect exactly kind small shift frequency Reminds Catch 22 doesnt point should point out servos controlled same way send little pulses voltage ON-time pulse determines servo out put shaft position see Fig 2 FM receiver little less ideal too theory ideal FM receiver ampli fies received signals point can clean off incidental AM use its limiting stages see Fig 3 However AM coming RCnbAM transmitter goes way zero also has exactly same configuration valid control signal should able see limiter cant get rid really wanted jam RCnbFM youd hard put find better way using RCnbAM now should grasp RCnbAM transmitter can control RCnbFM receiver amount AM put out RCnbFM transmitter negligible So does RCnbFM transmitter manage control RCnbAM receiver bandwidths RC AM FM sys tems have essentially same characteris tics Without becoming overly technical should able visualize RC sys tems spaced 10 kHz away other Common Carrier systems must neces sity use bandwidths equal less half distance between channel centers Therefore new narrow-band RC sys tems must use bandwidths 5 kHzor lessfor both AM FM systems IF intermediate frequency section RC receiver must designed cut off infor mation sharply slightly before 5 kHz points minimize adjacent-channel interference problems see Fig 4 Now lets take look what happens RCnbFM signal passes through real RCnbAM receiver happiest circumstances center frequency interfering RCnbFM transmitter happens land passband RCnbAM receiver deviated FM signal also lands within passband outputs two signals will equal shown Fig 5a voltage will sent servo wont pulse As consequence no interference control will result QSEE HOT STUFFTVIDEO-TI PS VHS CASSETTES #S 1 2 CLIP THIS COUPON SEND $5500 check MO GET BOTH VHS TAPES PLUS 1 EA 2 oz HOT STUFF 2 oz SUPER T 3 oz HOT SHOT FREE OFFER GOOD IN U S ONLY THRU JUNE 84 PO BOX 836 h4 S MI CA 93062 805 522-0062 126 Model Aviation Reservations Salt Fork Lodge Box 7 Cambridge OH 43725 800 282-7275 DIRECTIONS$54/night double US 22 East tram 177 just north Cambridge AMAIMA4IMACQSPRA Workshops will conducted areas RC including Gliders Gene Shelkey Electric Helicopters Fabricating Scale Parts Ed Wisser Monokoting Ramona Schultz Foam Cutting Bob Wallace other workshops Sigs Dave Brown Mark Ratcliffe Al Seidowski DISTRICT 3 MEETING further information call write Bob Button216343-7906 712 E 4th St Dover OH 44622 1731 6* 45 Street Ft Lauderdale FL 33309 13051 491-61 15 THE LANDING GEAR PEOPLE Tired 1 kit landing gears dcii III biggie property 0 & 0 Engineertug can solve problemil * Custom bout needs & specs guoranteod tit * Strong & durable withstand toighest landiog * 0 & 0 Eugloesriog gear wilt work & keep ysur biggie Ilylog * In otock roplaceweot gear br popular models Byron PIlls Cbniten Eagle LAP 21 Balsa USA J-3 CUB Air Tech Pawnee aid Eugle Nose Big Stick Champ ClIabria II & 0 medeli Soapper Stinger ond Snapper Tii However todays crystals usually ac curate 18 kHz average 075 kHz best worst-case analysis take double value difference between center frequencies RCnbAM transmitter interfering RCnbFM system Now add 3-5 kHz FM deviation believe will find cases deviation will land outside RCnbAM receivers passband Fig Sb As result decoded FM signal will now generate pulses can con trol servoeven though servo hooked AM receiver might led ask dont FM set manufacturers select crystals deviations centered band know might doing would help new FM set avoid interference AM set crystal AM set also perfectly centered band Tolerances being what wouldnt want bet hap pening Repeating what said above its nor mal see FM transmitter controlling AM receiver vice versa cant fly AM FM same channel same time Bob Aberle test new RC systems gets business being RC equipment reviewer will put test airplane up quite high turn other kind transmitter same channel general FM systems seem resist interference better please dont make mistake thinking re sistance absolute test involves slowly collapsing antenna transmitter system ing tested until test airplane throws fit get very busy yanking out test antenna turning off interference Usually FM antenna collapsed excitement starts AM tenna opposite test thing remember always hits other Continued page 130 CHUCK WOOD I-lank Clark5M0 RE5T N PE5TON ~TTY LADV 0$ IVIY GOD YOURE IFVOU SAYSO r GIRLS MEETWELL- DOHAVL TERRIRC 7 WERE ALL FAST IS THIS TME K wboDf CAIAETOSEE CIUCK WOODY4MPLAY0VE AT ROOD FREAKS~LLGETYOU HEADQUARTERSOH MOW UTTERL& SOME OF THE ES 2ACK QUICKY IMAGiNE FOR AMAFANTASTICALLY N MEN HERET LUNCH AwDAND AMGrRIS HAVING MARINE RET0N IGHTFULT -TI-4ERE ARE LOVE TO HAVE YOUHUN&R~ 4 HE LOOKS FOR LUNCI4 /IOw DID MEN HERE JOIN USi9- DELICIOUStHAT OLD 6$L$ /MAlhIK CLAR \lIIt//W~EVER DREAM U a- OUCAME YJET ************* * ******#****** * * * * WANDITTM * *Dealers Invited * * aim year ~1OftCORDJ orOry Stick en Abrasives * *A Keen Machinethat gives esceptienal *sandng central foran excellent finish. * *899 Basic mcI1 flat Wand *ef 6 grits *1 O8~Bailder Special mcI 2 ftat half 4 *reand wand 5 eacn 6 grits *1 295Deluxe includes 3 flat 2 half *raved wandsI buff wanes axe *tO 6 grits * *Additiexal Wands Abrasues availablK * year lecal hebby shap 4 *ADO IS ELMORE tee No i2t41 288 5789 * ox 266 uite Texas 751494 * February 1984 127 IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CID QUADRA010950 Rag 22 QUADRA $10450 Brisighef Ia Flywheel 612450 Rag 22 QUADRA POWER ASSEMBLY ONLY $9450 QUADRA REPAIR 1000 plus pans Jin Masse ERCOUPEPLANS $2395 KIT $23995 Jim Masser TOMAHAWKPLANS 62395 KIT $25995 Jo, Masse 9-BALL TRAINER PLANS $1895 KIT $9995 BALSA BASSWOOD taft sicesl 35% OFF Concept FLEET PLANS $2995 KIT $15095 COWL $1995 FLOATS 36~Il5 scale cores $1795 complete kit $3995 FLOATS 48V scalexmas $2195 complete kit $4795 CECONITE Products 1$% OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN lGodfrayl $2895 STARDUSTER TOO IBrisighetlal N J3 CUB NaIlS $2995 VOLKSPLANE N Chicken Charliel $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2295 Ercoupe $2095 Stearmas $2295 Citabria $2495 J3 Cob $2195 MElDS $2295 Fleet $2195 US Quadra FUEL TANKS16 oa $895 32 sa $795 FIBERGLASS ARROW SHAFTS 5116 32 long 8101000 24-Hour Sarsice d $25Opost*gB Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 VaIloy View Dr Allogany NV 14706 Send S100 Cash Check Stamps 32 Page Tabloid size illustrated DISCOUNT Catalog Sent 1st Class Mail COMET COX FLYLINE FOX GOLDBERG GUILLOWS JETCO K&B PACTRA POLYMER PERFECT SIG- STERLING LLIVAN TOP FLITE & OTHERS PENN VALLEY HOBBY CENTER 837 W Main St LansaIsa194I6 ixisi 55$ iaos 165 0x70 D EHINGE hinge allows control surface removal tools transportation Storage etc PATENTcovei I7IW Scale Appearance InsertSimple Assembly 3 SIZES No Slots No Pins 14-6 $335 38-6 $445 ATTENTION ERS beginner p. written illus trated R/Cer over 50 years model air plane experience Teaches basic model aerodynam ics commonsense manner. covers radio equipment learning fly much Easy understand must R/C modelers library $1195 Please add $100 ordered direct Available hobby shops order direct ACE R/C BOX 5110 HIGGINSVILLE MO 64037 GREAT PLANES MODEL DISTRIBUTOR BOX 725 URBANA ILLINOIS 61801 ZENITH AVIATION BOOKS BOX 14 OSCEOLA WISCONSIN 54020 Radio Technique/Myers Continued fmm paqe 126 under some conditions Thats cant fly FM AM systems same RC channel same time George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 RC Aerobatics/Van Putte Continued paqe 43 flight time limit pilot must still com mence takeoff within three minutes will have no time limit after Did hear big cheer Expert-class fliers option pilot choose up wind downwind direction has eliminated pilot must fly maneuvers actual directions listed maneu ver sequence So much us like perform rolling maneuvers right left exclusive right equal exposure judges has eliminated Contest Directors encouraged provide equal exposure required disqualify flights adverse weather causes unequal ex posure presume Contest Directors will still required provide equal ex posure good weather prevails old rule applauded fliers past does create hardship CDs judges typical two-flight-line contest 40 contestants six rounds possible order provide equal exposure judges hedge adverse weather problems judging set should line first two rounds another set next two means set judges must line six hours time eliminates some judges cant maintain judging quality long viable alternative to have set judges first third rounds another set second fourth rounds Equal exposure front two sets judges will achieved end fourth round another set hardy judges must line last two rounds However equal exposure achieved4 flier think its worth effort new rule have reservations about states Contest Director must set number flights flown before flying begins number may shortened due adverse weatherbut increased rule will limit CDs options Un fortunately very seldom con testants arrive before middle first round much less before flying begins beginning contest CD will forced guess rounds can flown some cases contest will over first day fewer fliers show up expected other hand surge late entries could cause long-running con test new rule changes number flights count final score good because extends reward consistency Now past4 best flight counted two flights flown4 best two counted three flights flown best three count four five flights flown change best four flights will count six flights flown will 130 Model Aviation Rotate EPOXY GLASS COWLS FOR NOSENPVCA SIO MORGAN BALSA USA PLAfl CONCEPT FLEET HOSTETLER RCM TCP4fl SHEBER PIUS & SCALE SUPER CUB FOKKER 0-7 BOEING P42 P-26 P482 F4B4 SPARROW HAWK GEE BEE MOO RIENS TURBULENT CHRIS TEN EAGLE BRISIGHELLAS STAROUSTER II SCALE J3-BI BABY FL YBABY AIRCAMPER PILOT .OURGMANN 7s35 SCALE 7/4 SCALE DECATHALON PIPER PAIB & OTHERS WHEEL PANTS FOR CITABRIA STAROUS TEN II P1775 SKYBOLT LIBER TV SPORT CHRISTEN EAGLE P6 E HAWK STEARMAN STINSON SR-B MULLIGAN & OTHERS 3R4ZED & HEAT-TREATED WIRE GEARS& CABANES LARGE SCALE PLANS AVAILABLE Send $100 latest list supply Modelers fiberglass parts plansWrite call us T 6 D FIBERGLASS SPECIALTIES 30925 BLOcK GARDEN CITY MI 48135 PHONE 313 421-6358 480 S*,4 Woe0*4 V4 WHY m 440W USE *44000PUS 44O00Th4000400044044o 4 40 04 04440444000 0004440404444 TOE 40004E4 000 0444444 440*440/Cm TO 44*04 P44444*440444444/40•LE P044440Th 44440*44410440404404/04 WE NEED YOUR have made videotapes club events especially MALL SHOWS AMAs PR Department would like use future projects will send us tapes will copy return quickly Please send tapes Doug Pratt AMA Public Relations Department 1810 Samuel Morse Drive Reston VA 22090
Edition: Model Aviation - 1984/02
Page Numbers: 38, 39, 122, 123, 126
a loec ni ue George M Myers FIGURE 1 FRE1/EAIFY M 5 kI M9 Cc new narrow-band RC receivers respond transmitted signal somewhat like figure showsexcept real-world hardware doesnt have such sharp square cutoffs z limits RC stands exact legal frequency RC transmitter CC stands frequency Common Canier transmitter Join us month find Out about new RC gear really worksand what difference between familiar AM systems new FM ones AM OFF- NO TRANSMISSION euRSTS o- 72CXJ MN FM FIGURE 2 V L IFT lb 2Xx5 MHj examined what transmissions two RC transmitters looked like oscilloscope youd see something like RC systems send out bursts information AM system top does turning transmitter Off precise intervais FM system lower does abruptly shifting its transmission frequency small amount approximately 005 MHz shown receiver sees operations its decoder translates signals useful informationit tells servos what position move NEW advent new RC frequen cies has added just bunch new frequencies us fly onthe FCC regu lations also allow us use new method radio transmission FM past RC sets have used either CW carrier wave signals switched Off mainly back early days singlechannel rudder-only rubberband-powered escapement systems AM amplitude modulation AM familiar practically everyone worldits what radio stations used until fairly recent times now entertainment radio stations using FM frequency modulation transmission lets us have true high-fidelity sound resistant static Now know cant listen FM radio station AM radio vice versa right thats true same situation must occur FM AM RC gear right Wrong such strange situation going take close look month What going talk about Will AM transmitters fly FM receivers vice versa think very timely question Im addressing direct result letter read ers David Shema AMA 5180 lives Bozeman MT Last month bought new JR Century VII Helicopter radio FM system RC42 ck would have first day new JR field another flier showed up Futaba FP-7GK RC42 AM set Since first far FM set club being curious tried following experiment 1 Turned ON FM transmitter AM receiver Result solid con trol over planethe servo func tions moved around solid controlno glitches no jit ter 2 Turned everything OFF Turned AM transmitter FM receiver Result he solid control over Heliboy 3 Later day flying about 200 feet away turned receiver still solid control Heliboy ground well airplane air 4 When flying done went over house look trans mitter signals oscilloscope 38 Model Aviation hi1416H LOW 0 Iu 0 Sure enough clearly FM typical AM question normal must compliment Mr Shema sys tematically checking through new situa tion keep saying people should make tests what observe few actually Its gratifying meet does emphatic point want make results Mr Shema obtained en tirely normal Commercial AM FM broadcast radios free mutual interference two reasons operate different radio frequencies RF 1 AM 055 thru 160 MHz 2 FM 88 thru 108 MHz 2 use different intermediate frequencies IF 1 AM uses 455 MHz 2 FM uses 107 MHz RC AM FM transmissions same RC channel will interfere another because will using same RE will 50 new channels authorized RC model aircraft Both will also using 455 MHz IF except rare dualconversion sets use 107 MHz well An unthinking few have suggested us ing old RC crystals new FM RC sys tems idea both illegal foolish reason worked hard get away old 7208 etc chan nels because overrun interference FM Both AM FM RC signals really two-valued signals system works varying transmitted signal between RC channel frequency 'something else FM case something else frequency three five kHz above below RC channels crystal-controlled stable frequency very small change AM case shift big y zero Hz same DC OFF see Fig 1 RC narrow-band FM RCnbFM really isnt frequency modulation classic communications sense Its modulation mode Frequency-Shift Keying FSK means deviates steps abruptly frequency other rather swinging more-or-less smoothly within limits deviation range 5 kHz RC would case responding voice music have digital computer tele phone modem know uses FSK putting data telephone line through modem should easy understand RCnbFM really uses digital signal form though infor mation carried analog way length time information-pulse ON represents position control stick/knob/lever RC Narrow-band AM RCnbAM isnt SERVOSRVOSERVOSERVO IZ3 FIGURE servos BC system fed diet voltage pulses receiver/decoder servo knows what position has string pulses uses width pulse detemilne position has commanded assume M1E AM AND FM II LIMITERII CIRCUIT Li FIGURE 4 II FM aty An FM receiver has circuit called iimiterit strips off AM-type characteristics signal received before processing signal further AM ThANSMISSION bI/&H VOL 73 FIGURE 5 RA4//v7 TT OFF Loul 4/01-75 FAI TRAAISM 155/OAf OUflU ALWAYS /116A/ 72cXc 7OC5PASS 5AAAD FM NOT CEWTEED 7 xxx 72 7205 iRA NSfr7/T7R 04 RdDUCC3 ADROL PUL ~-5 J FM Pobuc65 Ce~u7ROL PULSES Believe new narrow-band RC systems possible FM transmitter interfere control AM receivr AM transmitter interfere control FM receiver figure alone may tell too muchbut George has very good description what happening months column Read heed amplitude modulation classic commu nications sense either Commercial AM ra dio stations avoid 100% modulation swing ing RE amplitude zero because distorts message causes spatter lets signal appear other places RE band isnt wanted RCnbAM systems switch transmitters crystal-controlled oscillator ON/OFF send control information Information carried analog based length time pulse ON explained before bothered kind distortion Continued page 126 February 1984 39 SAL TFORKII District 3 Symposium Workshop Jan 14-15 1984Sponsored Tusco RC Club Admission $500 y $800 ys Wives Free P-38IBrown Continued oaoe 123 Surface movements should approxi mately follows rudders 3/s-in both ways ailerons /4-in both ways elevator 5/6-in both wayswith little bit uptrim start Aileron response posi tive like full-size aircraft roll rate slow Ailerons rudders needed no trim adjustments elevator model needed bit up-trim offset nose-heaviness Landings Cub-like need full throttle first flight make few landing approaches well before fuel runs low get feel sink rate Dont try come final nose too high keep level down slightly until just before touchdown flair slightly have done some low-speed testing model altitude course hangs stalling surprisingly well youve always wanted try twin boxy add-an-engine designs turn off try racy P-38 Theres nothing like twinon ground especially air Radio Technique/Myers Continued aoe 39 would confuse voice music RC systems designers very concerned spatter however dont actually use ON/OFF switching Instead use shaped tran sition ON OFF ON minimizes spatter Just make things bit complex significant deviations ideal performance hardware both sys tems As consequence ON/OFF signalshaping mentioned above AM trans mitter puts little frequency shift transmitted RF signal time turns signal ON OFF shift FM its minor amount its needed control spatter shift decoded narrow-band FM receiver because re ceiver designed detect exactly kind small shift frequency Reminds Catch 22 doesnt point should point out servos controlled same way send little pulses voltage ON-time pulse determines servo out put shaft position see Fig 2 FM receiver little less ideal too theory ideal FM receiver ampli fies received signals point can clean off incidental AM use its limiting stages see Fig 3 However AM coming RCnbAM transmitter goes way zero also has exactly same configuration valid control signal should able see limiter cant get rid really wanted jam RCnbFM youd hard put find better way using RCnbAM now should grasp RCnbAM transmitter can control RCnbFM receiver amount AM put out RCnbFM transmitter negligible So does RCnbFM transmitter manage control RCnbAM receiver bandwidths RC AM FM sys tems have essentially same characteris tics Without becoming overly technical should able visualize RC sys tems spaced 10 kHz away other Common Carrier systems must neces sity use bandwidths equal less half distance between channel centers Therefore new narrow-band RC sys tems must use bandwidths 5 kHzor lessfor both AM FM systems IF intermediate frequency section RC receiver must designed cut off infor mation sharply slightly before 5 kHz points minimize adjacent-channel interference problems see Fig 4 Now lets take look what happens RCnbFM signal passes through real RCnbAM receiver happiest circumstances center frequency interfering RCnbFM transmitter happens land passband RCnbAM receiver deviated FM signal also lands within passband outputs two signals will equal shown Fig 5a voltage will sent servo wont pulse As consequence no interference control will result QSEE HOT STUFFTVIDEO-TI PS VHS CASSETTES #S 1 2 CLIP THIS COUPON SEND $5500 check MO GET BOTH VHS TAPES PLUS 1 EA 2 oz HOT STUFF 2 oz SUPER T 3 oz HOT SHOT FREE OFFER GOOD IN U S ONLY THRU JUNE 84 PO BOX 836 h4 S MI CA 93062 805 522-0062 126 Model Aviation Reservations Salt Fork Lodge Box 7 Cambridge OH 43725 800 282-7275 DIRECTIONS$54/night double US 22 East tram 177 just north Cambridge AMAIMA4IMACQSPRA Workshops will conducted areas RC including Gliders Gene Shelkey Electric Helicopters Fabricating Scale Parts Ed Wisser Monokoting Ramona Schultz Foam Cutting Bob Wallace other workshops Sigs Dave Brown Mark Ratcliffe Al Seidowski DISTRICT 3 MEETING further information call write Bob Button216343-7906 712 E 4th St Dover OH 44622 1731 6* 45 Street Ft Lauderdale FL 33309 13051 491-61 15 THE LANDING GEAR PEOPLE Tired 1 kit landing gears dcii III biggie property 0 & 0 Engineertug can solve problemil * Custom bout needs & specs guoranteod tit * Strong & durable withstand toighest landiog * 0 & 0 Eugloesriog gear wilt work & keep ysur biggie Ilylog * In otock roplaceweot gear br popular models Byron PIlls Cbniten Eagle LAP 21 Balsa USA J-3 CUB Air Tech Pawnee aid Eugle Nose Big Stick Champ ClIabria II & 0 medeli Soapper Stinger ond Snapper Tii However todays crystals usually ac curate 18 kHz average 075 kHz best worst-case analysis take double value difference between center frequencies RCnbAM transmitter interfering RCnbFM system Now add 3-5 kHz FM deviation believe will find cases deviation will land outside RCnbAM receivers passband Fig Sb As result decoded FM signal will now generate pulses can con trol servoeven though servo hooked AM receiver might led ask dont FM set manufacturers select crystals deviations centered band know might doing would help new FM set avoid interference AM set crystal AM set also perfectly centered band Tolerances being what wouldnt want bet hap pening Repeating what said above its nor mal see FM transmitter controlling AM receiver vice versa cant fly AM FM same channel same time Bob Aberle test new RC systems gets business being RC equipment reviewer will put test airplane up quite high turn other kind transmitter same channel general FM systems seem resist interference better please dont make mistake thinking re sistance absolute test involves slowly collapsing antenna transmitter system ing tested until test airplane throws fit get very busy yanking out test antenna turning off interference Usually FM antenna collapsed excitement starts AM tenna opposite test thing remember always hits other Continued page 130 CHUCK WOOD I-lank Clark5M0 RE5T N PE5TON ~TTY LADV 0$ IVIY GOD YOURE IFVOU SAYSO r GIRLS MEETWELL- DOHAVL TERRIRC 7 WERE ALL FAST IS THIS TME K wboDf CAIAETOSEE CIUCK WOODY4MPLAY0VE AT ROOD FREAKS~LLGETYOU HEADQUARTERSOH MOW UTTERL& SOME OF THE ES 2ACK QUICKY IMAGiNE FOR AMAFANTASTICALLY N MEN HERET LUNCH AwDAND AMGrRIS HAVING MARINE RET0N IGHTFULT -TI-4ERE ARE LOVE TO HAVE YOUHUN&R~ 4 HE LOOKS FOR LUNCI4 /IOw DID MEN HERE JOIN USi9- DELICIOUStHAT OLD 6$L$ /MAlhIK CLAR \lIIt//W~EVER DREAM U a- OUCAME YJET ************* * ******#****** * * * * WANDITTM * *Dealers Invited * * aim year ~1OftCORDJ orOry Stick en Abrasives * *A Keen Machinethat gives esceptienal *sandng central foran excellent finish. * *899 Basic mcI1 flat Wand *ef 6 grits *1 O8~Bailder Special mcI 2 ftat half 4 *reand wand 5 eacn 6 grits *1 295Deluxe includes 3 flat 2 half *raved wandsI buff wanes axe *tO 6 grits * *Additiexal Wands Abrasues availablK * year lecal hebby shap 4 *ADO IS ELMORE tee No i2t41 288 5789 * ox 266 uite Texas 751494 * February 1984 127 IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CID QUADRA010950 Rag 22 QUADRA $10450 Brisighef Ia Flywheel 612450 Rag 22 QUADRA POWER ASSEMBLY ONLY $9450 QUADRA REPAIR 1000 plus pans Jin Masse ERCOUPEPLANS $2395 KIT $23995 Jim Masser TOMAHAWKPLANS 62395 KIT $25995 Jo, Masse 9-BALL TRAINER PLANS $1895 KIT $9995 BALSA BASSWOOD taft sicesl 35% OFF Concept FLEET PLANS $2995 KIT $15095 COWL $1995 FLOATS 36~Il5 scale cores $1795 complete kit $3995 FLOATS 48V scalexmas $2195 complete kit $4795 CECONITE Products 1$% OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN lGodfrayl $2895 STARDUSTER TOO IBrisighetlal N J3 CUB NaIlS $2995 VOLKSPLANE N Chicken Charliel $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2295 Ercoupe $2095 Stearmas $2295 Citabria $2495 J3 Cob $2195 MElDS $2295 Fleet $2195 US Quadra FUEL TANKS16 oa $895 32 sa $795 FIBERGLASS ARROW SHAFTS 5116 32 long 8101000 24-Hour Sarsice d $25Opost*gB Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 VaIloy View Dr Allogany NV 14706 Send S100 Cash Check Stamps 32 Page Tabloid size illustrated DISCOUNT Catalog Sent 1st Class Mail COMET COX FLYLINE FOX GOLDBERG GUILLOWS JETCO K&B PACTRA POLYMER PERFECT SIG- STERLING LLIVAN TOP FLITE & OTHERS PENN VALLEY HOBBY CENTER 837 W Main St LansaIsa194I6 ixisi 55$ iaos 165 0x70 D EHINGE hinge allows control surface removal tools transportation Storage etc PATENTcovei I7IW Scale Appearance InsertSimple Assembly 3 SIZES No Slots No Pins 14-6 $335 38-6 $445 ATTENTION ERS beginner p. written illus trated R/Cer over 50 years model air plane experience Teaches basic model aerodynam ics commonsense manner. covers radio equipment learning fly much Easy understand must R/C modelers library $1195 Please add $100 ordered direct Available hobby shops order direct ACE R/C BOX 5110 HIGGINSVILLE MO 64037 GREAT PLANES MODEL DISTRIBUTOR BOX 725 URBANA ILLINOIS 61801 ZENITH AVIATION BOOKS BOX 14 OSCEOLA WISCONSIN 54020 Radio Technique/Myers Continued fmm paqe 126 under some conditions Thats cant fly FM AM systems same RC channel same time George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 RC Aerobatics/Van Putte Continued paqe 43 flight time limit pilot must still com mence takeoff within three minutes will have no time limit after Did hear big cheer Expert-class fliers option pilot choose up wind downwind direction has eliminated pilot must fly maneuvers actual directions listed maneu ver sequence So much us like perform rolling maneuvers right left exclusive right equal exposure judges has eliminated Contest Directors encouraged provide equal exposure required disqualify flights adverse weather causes unequal ex posure presume Contest Directors will still required provide equal ex posure good weather prevails old rule applauded fliers past does create hardship CDs judges typical two-flight-line contest 40 contestants six rounds possible order provide equal exposure judges hedge adverse weather problems judging set should line first two rounds another set next two means set judges must line six hours time eliminates some judges cant maintain judging quality long viable alternative to have set judges first third rounds another set second fourth rounds Equal exposure front two sets judges will achieved end fourth round another set hardy judges must line last two rounds However equal exposure achieved4 flier think its worth effort new rule have reservations about states Contest Director must set number flights flown before flying begins number may shortened due adverse weatherbut increased rule will limit CDs options Un fortunately very seldom con testants arrive before middle first round much less before flying begins beginning contest CD will forced guess rounds can flown some cases contest will over first day fewer fliers show up expected other hand surge late entries could cause long-running con test new rule changes number flights count final score good because extends reward consistency Now past4 best flight counted two flights flown4 best two counted three flights flown best three count four five flights flown change best four flights will count six flights flown will 130 Model Aviation Rotate EPOXY GLASS COWLS FOR NOSENPVCA SIO MORGAN BALSA USA PLAfl CONCEPT FLEET HOSTETLER RCM TCP4fl SHEBER PIUS & SCALE SUPER CUB FOKKER 0-7 BOEING P42 P-26 P482 F4B4 SPARROW HAWK GEE BEE MOO RIENS TURBULENT CHRIS TEN EAGLE BRISIGHELLAS STAROUSTER II SCALE J3-BI BABY FL YBABY AIRCAMPER PILOT .OURGMANN 7s35 SCALE 7/4 SCALE DECATHALON PIPER PAIB & OTHERS WHEEL PANTS FOR CITABRIA STAROUS TEN II P1775 SKYBOLT LIBER TV SPORT CHRISTEN EAGLE P6 E HAWK STEARMAN STINSON SR-B MULLIGAN & OTHERS 3R4ZED & HEAT-TREATED WIRE GEARS& CABANES LARGE SCALE PLANS AVAILABLE Send $100 latest list supply Modelers fiberglass parts plansWrite call us T 6 D FIBERGLASS SPECIALTIES 30925 BLOcK GARDEN CITY MI 48135 PHONE 313 421-6358 480 S*,4 Woe0*4 V4 WHY m 440W USE *44000PUS 44O00Th4000400044044o 4 40 04 04440444000 0004440404444 TOE 40004E4 000 0444444 440*440/Cm TO 44*04 P44444*440444444/40•LE P044440Th 44440*44410440404404/04 WE NEED YOUR have made videotapes club events especially MALL SHOWS AMAs PR Department would like use future projects will send us tapes will copy return quickly Please send tapes Doug Pratt AMA Public Relations Department 1810 Samuel Morse Drive Reston VA 22090
Edition: Model Aviation - 1984/02
Page Numbers: 38, 39, 122, 123, 126
a loec ni ue George M Myers FIGURE 1 FRE1/EAIFY M 5 kI M9 Cc new narrow-band RC receivers respond transmitted signal somewhat like figure showsexcept real-world hardware doesnt have such sharp square cutoffs z limits RC stands exact legal frequency RC transmitter CC stands frequency Common Canier transmitter Join us month find Out about new RC gear really worksand what difference between familiar AM systems new FM ones AM OFF- NO TRANSMISSION euRSTS o- 72CXJ MN FM FIGURE 2 V L IFT lb 2Xx5 MHj examined what transmissions two RC transmitters looked like oscilloscope youd see something like RC systems send out bursts information AM system top does turning transmitter Off precise intervais FM system lower does abruptly shifting its transmission frequency small amount approximately 005 MHz shown receiver sees operations its decoder translates signals useful informationit tells servos what position move NEW advent new RC frequen cies has added just bunch new frequencies us fly onthe FCC regu lations also allow us use new method radio transmission FM past RC sets have used either CW carrier wave signals switched Off mainly back early days singlechannel rudder-only rubberband-powered escapement systems AM amplitude modulation AM familiar practically everyone worldits what radio stations used until fairly recent times now entertainment radio stations using FM frequency modulation transmission lets us have true high-fidelity sound resistant static Now know cant listen FM radio station AM radio vice versa right thats true same situation must occur FM AM RC gear right Wrong such strange situation going take close look month What going talk about Will AM transmitters fly FM receivers vice versa think very timely question Im addressing direct result letter read ers David Shema AMA 5180 lives Bozeman MT Last month bought new JR Century VII Helicopter radio FM system RC42 ck would have first day new JR field another flier showed up Futaba FP-7GK RC42 AM set Since first far FM set club being curious tried following experiment 1 Turned ON FM transmitter AM receiver Result solid con trol over planethe servo func tions moved around solid controlno glitches no jit ter 2 Turned everything OFF Turned AM transmitter FM receiver Result he solid control over Heliboy 3 Later day flying about 200 feet away turned receiver still solid control Heliboy ground well airplane air 4 When flying done went over house look trans mitter signals oscilloscope 38 Model Aviation hi1416H LOW 0 Iu 0 Sure enough clearly FM typical AM question normal must compliment Mr Shema sys tematically checking through new situa tion keep saying people should make tests what observe few actually Its gratifying meet does emphatic point want make results Mr Shema obtained en tirely normal Commercial AM FM broadcast radios free mutual interference two reasons operate different radio frequencies RF 1 AM 055 thru 160 MHz 2 FM 88 thru 108 MHz 2 use different intermediate frequencies IF 1 AM uses 455 MHz 2 FM uses 107 MHz RC AM FM transmissions same RC channel will interfere another because will using same RE will 50 new channels authorized RC model aircraft Both will also using 455 MHz IF except rare dualconversion sets use 107 MHz well An unthinking few have suggested us ing old RC crystals new FM RC sys tems idea both illegal foolish reason worked hard get away old 7208 etc chan nels because overrun interference FM Both AM FM RC signals really two-valued signals system works varying transmitted signal between RC channel frequency 'something else FM case something else frequency three five kHz above below RC channels crystal-controlled stable frequency very small change AM case shift big y zero Hz same DC OFF see Fig 1 RC narrow-band FM RCnbFM really isnt frequency modulation classic communications sense Its modulation mode Frequency-Shift Keying FSK means deviates steps abruptly frequency other rather swinging more-or-less smoothly within limits deviation range 5 kHz RC would case responding voice music have digital computer tele phone modem know uses FSK putting data telephone line through modem should easy understand RCnbFM really uses digital signal form though infor mation carried analog way length time information-pulse ON represents position control stick/knob/lever RC Narrow-band AM RCnbAM isnt SERVOSRVOSERVOSERVO IZ3 FIGURE servos BC system fed diet voltage pulses receiver/decoder servo knows what position has string pulses uses width pulse detemilne position has commanded assume M1E AM AND FM II LIMITERII CIRCUIT Li FIGURE 4 II FM aty An FM receiver has circuit called iimiterit strips off AM-type characteristics signal received before processing signal further AM ThANSMISSION bI/&H VOL 73 FIGURE 5 RA4//v7 TT OFF Loul 4/01-75 FAI TRAAISM 155/OAf OUflU ALWAYS /116A/ 72cXc 7OC5PASS 5AAAD FM NOT CEWTEED 7 xxx 72 7205 iRA NSfr7/T7R 04 RdDUCC3 ADROL PUL ~-5 J FM Pobuc65 Ce~u7ROL PULSES Believe new narrow-band RC systems possible FM transmitter interfere control AM receivr AM transmitter interfere control FM receiver figure alone may tell too muchbut George has very good description what happening months column Read heed amplitude modulation classic commu nications sense either Commercial AM ra dio stations avoid 100% modulation swing ing RE amplitude zero because distorts message causes spatter lets signal appear other places RE band isnt wanted RCnbAM systems switch transmitters crystal-controlled oscillator ON/OFF send control information Information carried analog based length time pulse ON explained before bothered kind distortion Continued page 126 February 1984 39 SAL TFORKII District 3 Symposium Workshop Jan 14-15 1984Sponsored Tusco RC Club Admission $500 y $800 ys Wives Free P-38IBrown Continued oaoe 123 Surface movements should approxi mately follows rudders 3/s-in both ways ailerons /4-in both ways elevator 5/6-in both wayswith little bit uptrim start Aileron response posi tive like full-size aircraft roll rate slow Ailerons rudders needed no trim adjustments elevator model needed bit up-trim offset nose-heaviness Landings Cub-like need full throttle first flight make few landing approaches well before fuel runs low get feel sink rate Dont try come final nose too high keep level down slightly until just before touchdown flair slightly have done some low-speed testing model altitude course hangs stalling surprisingly well youve always wanted try twin boxy add-an-engine designs turn off try racy P-38 Theres nothing like twinon ground especially air Radio Technique/Myers Continued aoe 39 would confuse voice music RC systems designers very concerned spatter however dont actually use ON/OFF switching Instead use shaped tran sition ON OFF ON minimizes spatter Just make things bit complex significant deviations ideal performance hardware both sys tems As consequence ON/OFF signalshaping mentioned above AM trans mitter puts little frequency shift transmitted RF signal time turns signal ON OFF shift FM its minor amount its needed control spatter shift decoded narrow-band FM receiver because re ceiver designed detect exactly kind small shift frequency Reminds Catch 22 doesnt point should point out servos controlled same way send little pulses voltage ON-time pulse determines servo out put shaft position see Fig 2 FM receiver little less ideal too theory ideal FM receiver ampli fies received signals point can clean off incidental AM use its limiting stages see Fig 3 However AM coming RCnbAM transmitter goes way zero also has exactly same configuration valid control signal should able see limiter cant get rid really wanted jam RCnbFM youd hard put find better way using RCnbAM now should grasp RCnbAM transmitter can control RCnbFM receiver amount AM put out RCnbFM transmitter negligible So does RCnbFM transmitter manage control RCnbAM receiver bandwidths RC AM FM sys tems have essentially same characteris tics Without becoming overly technical should able visualize RC sys tems spaced 10 kHz away other Common Carrier systems must neces sity use bandwidths equal less half distance between channel centers Therefore new narrow-band RC sys tems must use bandwidths 5 kHzor lessfor both AM FM systems IF intermediate frequency section RC receiver must designed cut off infor mation sharply slightly before 5 kHz points minimize adjacent-channel interference problems see Fig 4 Now lets take look what happens RCnbFM signal passes through real RCnbAM receiver happiest circumstances center frequency interfering RCnbFM transmitter happens land passband RCnbAM receiver deviated FM signal also lands within passband outputs two signals will equal shown Fig 5a voltage will sent servo wont pulse As consequence no interference control will result QSEE HOT STUFFTVIDEO-TI PS VHS CASSETTES #S 1 2 CLIP THIS COUPON SEND $5500 check MO GET BOTH VHS TAPES PLUS 1 EA 2 oz HOT STUFF 2 oz SUPER T 3 oz HOT SHOT FREE OFFER GOOD IN U S ONLY THRU JUNE 84 PO BOX 836 h4 S MI CA 93062 805 522-0062 126 Model Aviation Reservations Salt Fork Lodge Box 7 Cambridge OH 43725 800 282-7275 DIRECTIONS$54/night double US 22 East tram 177 just north Cambridge AMAIMA4IMACQSPRA Workshops will conducted areas RC including Gliders Gene Shelkey Electric Helicopters Fabricating Scale Parts Ed Wisser Monokoting Ramona Schultz Foam Cutting Bob Wallace other workshops Sigs Dave Brown Mark Ratcliffe Al Seidowski DISTRICT 3 MEETING further information call write Bob Button216343-7906 712 E 4th St Dover OH 44622 1731 6* 45 Street Ft Lauderdale FL 33309 13051 491-61 15 THE LANDING GEAR PEOPLE Tired 1 kit landing gears dcii III biggie property 0 & 0 Engineertug can solve problemil * Custom bout needs & specs guoranteod tit * Strong & durable withstand toighest landiog * 0 & 0 Eugloesriog gear wilt work & keep ysur biggie Ilylog * In otock roplaceweot gear br popular models Byron PIlls Cbniten Eagle LAP 21 Balsa USA J-3 CUB Air Tech Pawnee aid Eugle Nose Big Stick Champ ClIabria II & 0 medeli Soapper Stinger ond Snapper Tii However todays crystals usually ac curate 18 kHz average 075 kHz best worst-case analysis take double value difference between center frequencies RCnbAM transmitter interfering RCnbFM system Now add 3-5 kHz FM deviation believe will find cases deviation will land outside RCnbAM receivers passband Fig Sb As result decoded FM signal will now generate pulses can con trol servoeven though servo hooked AM receiver might led ask dont FM set manufacturers select crystals deviations centered band know might doing would help new FM set avoid interference AM set crystal AM set also perfectly centered band Tolerances being what wouldnt want bet hap pening Repeating what said above its nor mal see FM transmitter controlling AM receiver vice versa cant fly AM FM same channel same time Bob Aberle test new RC systems gets business being RC equipment reviewer will put test airplane up quite high turn other kind transmitter same channel general FM systems seem resist interference better please dont make mistake thinking re sistance absolute test involves slowly collapsing antenna transmitter system ing tested until test airplane throws fit get very busy yanking out test antenna turning off interference Usually FM antenna collapsed excitement starts AM tenna opposite test thing remember always hits other Continued page 130 CHUCK WOOD I-lank Clark5M0 RE5T N PE5TON ~TTY LADV 0$ IVIY GOD YOURE IFVOU SAYSO r GIRLS MEETWELL- DOHAVL TERRIRC 7 WERE ALL FAST IS THIS TME K wboDf CAIAETOSEE CIUCK WOODY4MPLAY0VE AT ROOD FREAKS~LLGETYOU HEADQUARTERSOH MOW UTTERL& SOME OF THE ES 2ACK QUICKY IMAGiNE FOR AMAFANTASTICALLY N MEN HERET LUNCH AwDAND AMGrRIS HAVING MARINE RET0N IGHTFULT -TI-4ERE ARE LOVE TO HAVE YOUHUN&R~ 4 HE LOOKS FOR LUNCI4 /IOw DID MEN HERE JOIN USi9- DELICIOUStHAT OLD 6$L$ /MAlhIK CLAR \lIIt//W~EVER DREAM U a- OUCAME YJET ************* * ******#****** * * * * WANDITTM * *Dealers Invited * * aim year ~1OftCORDJ orOry Stick en Abrasives * *A Keen Machinethat gives esceptienal *sandng central foran excellent finish. * *899 Basic mcI1 flat Wand *ef 6 grits *1 O8~Bailder Special mcI 2 ftat half 4 *reand wand 5 eacn 6 grits *1 295Deluxe includes 3 flat 2 half *raved wandsI buff wanes axe *tO 6 grits * *Additiexal Wands Abrasues availablK * year lecal hebby shap 4 *ADO IS ELMORE tee No i2t41 288 5789 * ox 266 uite Texas 751494 * February 1984 127 IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CID QUADRA010950 Rag 22 QUADRA $10450 Brisighef Ia Flywheel 612450 Rag 22 QUADRA POWER ASSEMBLY ONLY $9450 QUADRA REPAIR 1000 plus pans Jin Masse ERCOUPEPLANS $2395 KIT $23995 Jim Masser TOMAHAWKPLANS 62395 KIT $25995 Jo, Masse 9-BALL TRAINER PLANS $1895 KIT $9995 BALSA BASSWOOD taft sicesl 35% OFF Concept FLEET PLANS $2995 KIT $15095 COWL $1995 FLOATS 36~Il5 scale cores $1795 complete kit $3995 FLOATS 48V scalexmas $2195 complete kit $4795 CECONITE Products 1$% OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN lGodfrayl $2895 STARDUSTER TOO IBrisighetlal N J3 CUB NaIlS $2995 VOLKSPLANE N Chicken Charliel $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2295 Ercoupe $2095 Stearmas $2295 Citabria $2495 J3 Cob $2195 MElDS $2295 Fleet $2195 US Quadra FUEL TANKS16 oa $895 32 sa $795 FIBERGLASS ARROW SHAFTS 5116 32 long 8101000 24-Hour Sarsice d $25Opost*gB Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 VaIloy View Dr Allogany NV 14706 Send S100 Cash Check Stamps 32 Page Tabloid size illustrated DISCOUNT Catalog Sent 1st Class Mail COMET COX FLYLINE FOX GOLDBERG GUILLOWS JETCO K&B PACTRA POLYMER PERFECT SIG- STERLING LLIVAN TOP FLITE & OTHERS PENN VALLEY HOBBY CENTER 837 W Main St LansaIsa194I6 ixisi 55$ iaos 165 0x70 D EHINGE hinge allows control surface removal tools transportation Storage etc PATENTcovei I7IW Scale Appearance InsertSimple Assembly 3 SIZES No Slots No Pins 14-6 $335 38-6 $445 ATTENTION ERS beginner p. written illus trated R/Cer over 50 years model air plane experience Teaches basic model aerodynam ics commonsense manner. covers radio equipment learning fly much Easy understand must R/C modelers library $1195 Please add $100 ordered direct Available hobby shops order direct ACE R/C BOX 5110 HIGGINSVILLE MO 64037 GREAT PLANES MODEL DISTRIBUTOR BOX 725 URBANA ILLINOIS 61801 ZENITH AVIATION BOOKS BOX 14 OSCEOLA WISCONSIN 54020 Radio Technique/Myers Continued fmm paqe 126 under some conditions Thats cant fly FM AM systems same RC channel same time George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 RC Aerobatics/Van Putte Continued paqe 43 flight time limit pilot must still com mence takeoff within three minutes will have no time limit after Did hear big cheer Expert-class fliers option pilot choose up wind downwind direction has eliminated pilot must fly maneuvers actual directions listed maneu ver sequence So much us like perform rolling maneuvers right left exclusive right equal exposure judges has eliminated Contest Directors encouraged provide equal exposure required disqualify flights adverse weather causes unequal ex posure presume Contest Directors will still required provide equal ex posure good weather prevails old rule applauded fliers past does create hardship CDs judges typical two-flight-line contest 40 contestants six rounds possible order provide equal exposure judges hedge adverse weather problems judging set should line first two rounds another set next two means set judges must line six hours time eliminates some judges cant maintain judging quality long viable alternative to have set judges first third rounds another set second fourth rounds Equal exposure front two sets judges will achieved end fourth round another set hardy judges must line last two rounds However equal exposure achieved4 flier think its worth effort new rule have reservations about states Contest Director must set number flights flown before flying begins number may shortened due adverse weatherbut increased rule will limit CDs options Un fortunately very seldom con testants arrive before middle first round much less before flying begins beginning contest CD will forced guess rounds can flown some cases contest will over first day fewer fliers show up expected other hand surge late entries could cause long-running con test new rule changes number flights count final score good because extends reward consistency Now past4 best flight counted two flights flown4 best two counted three flights flown best three count four five flights flown change best four flights will count six flights flown will 130 Model Aviation Rotate EPOXY GLASS COWLS FOR NOSENPVCA SIO MORGAN BALSA USA PLAfl CONCEPT FLEET HOSTETLER RCM TCP4fl SHEBER PIUS & SCALE SUPER CUB FOKKER 0-7 BOEING P42 P-26 P482 F4B4 SPARROW HAWK GEE BEE MOO RIENS TURBULENT CHRIS TEN EAGLE BRISIGHELLAS STAROUSTER II SCALE J3-BI BABY FL YBABY AIRCAMPER PILOT .OURGMANN 7s35 SCALE 7/4 SCALE DECATHALON PIPER PAIB & OTHERS WHEEL PANTS FOR CITABRIA STAROUS TEN II P1775 SKYBOLT LIBER TV SPORT CHRISTEN EAGLE P6 E HAWK STEARMAN STINSON SR-B MULLIGAN & OTHERS 3R4ZED & HEAT-TREATED WIRE GEARS& CABANES LARGE SCALE PLANS AVAILABLE Send $100 latest list supply Modelers fiberglass parts plansWrite call us T 6 D FIBERGLASS SPECIALTIES 30925 BLOcK GARDEN CITY MI 48135 PHONE 313 421-6358 480 S*,4 Woe0*4 V4 WHY m 440W USE *44000PUS 44O00Th4000400044044o 4 40 04 04440444000 0004440404444 TOE 40004E4 000 0444444 440*440/Cm TO 44*04 P44444*440444444/40•LE P044440Th 44440*44410440404404/04 WE NEED YOUR have made videotapes club events especially MALL SHOWS AMAs PR Department would like use future projects will send us tapes will copy return quickly Please send tapes Doug Pratt AMA Public Relations Department 1810 Samuel Morse Drive Reston VA 22090
Edition: Model Aviation - 1984/02
Page Numbers: 38, 39, 122, 123, 126
a loec ni ue George M Myers FIGURE 1 FRE1/EAIFY M 5 kI M9 Cc new narrow-band RC receivers respond transmitted signal somewhat like figure showsexcept real-world hardware doesnt have such sharp square cutoffs z limits RC stands exact legal frequency RC transmitter CC stands frequency Common Canier transmitter Join us month find Out about new RC gear really worksand what difference between familiar AM systems new FM ones AM OFF- NO TRANSMISSION euRSTS o- 72CXJ MN FM FIGURE 2 V L IFT lb 2Xx5 MHj examined what transmissions two RC transmitters looked like oscilloscope youd see something like RC systems send out bursts information AM system top does turning transmitter Off precise intervais FM system lower does abruptly shifting its transmission frequency small amount approximately 005 MHz shown receiver sees operations its decoder translates signals useful informationit tells servos what position move NEW advent new RC frequen cies has added just bunch new frequencies us fly onthe FCC regu lations also allow us use new method radio transmission FM past RC sets have used either CW carrier wave signals switched Off mainly back early days singlechannel rudder-only rubberband-powered escapement systems AM amplitude modulation AM familiar practically everyone worldits what radio stations used until fairly recent times now entertainment radio stations using FM frequency modulation transmission lets us have true high-fidelity sound resistant static Now know cant listen FM radio station AM radio vice versa right thats true same situation must occur FM AM RC gear right Wrong such strange situation going take close look month What going talk about Will AM transmitters fly FM receivers vice versa think very timely question Im addressing direct result letter read ers David Shema AMA 5180 lives Bozeman MT Last month bought new JR Century VII Helicopter radio FM system RC42 ck would have first day new JR field another flier showed up Futaba FP-7GK RC42 AM set Since first far FM set club being curious tried following experiment 1 Turned ON FM transmitter AM receiver Result solid con trol over planethe servo func tions moved around solid controlno glitches no jit ter 2 Turned everything OFF Turned AM transmitter FM receiver Result he solid control over Heliboy 3 Later day flying about 200 feet away turned receiver still solid control Heliboy ground well airplane air 4 When flying done went over house look trans mitter signals oscilloscope 38 Model Aviation hi1416H LOW 0 Iu 0 Sure enough clearly FM typical AM question normal must compliment Mr Shema sys tematically checking through new situa tion keep saying people should make tests what observe few actually Its gratifying meet does emphatic point want make results Mr Shema obtained en tirely normal Commercial AM FM broadcast radios free mutual interference two reasons operate different radio frequencies RF 1 AM 055 thru 160 MHz 2 FM 88 thru 108 MHz 2 use different intermediate frequencies IF 1 AM uses 455 MHz 2 FM uses 107 MHz RC AM FM transmissions same RC channel will interfere another because will using same RE will 50 new channels authorized RC model aircraft Both will also using 455 MHz IF except rare dualconversion sets use 107 MHz well An unthinking few have suggested us ing old RC crystals new FM RC sys tems idea both illegal foolish reason worked hard get away old 7208 etc chan nels because overrun interference FM Both AM FM RC signals really two-valued signals system works varying transmitted signal between RC channel frequency 'something else FM case something else frequency three five kHz above below RC channels crystal-controlled stable frequency very small change AM case shift big y zero Hz same DC OFF see Fig 1 RC narrow-band FM RCnbFM really isnt frequency modulation classic communications sense Its modulation mode Frequency-Shift Keying FSK means deviates steps abruptly frequency other rather swinging more-or-less smoothly within limits deviation range 5 kHz RC would case responding voice music have digital computer tele phone modem know uses FSK putting data telephone line through modem should easy understand RCnbFM really uses digital signal form though infor mation carried analog way length time information-pulse ON represents position control stick/knob/lever RC Narrow-band AM RCnbAM isnt SERVOSRVOSERVOSERVO IZ3 FIGURE servos BC system fed diet voltage pulses receiver/decoder servo knows what position has string pulses uses width pulse detemilne position has commanded assume M1E AM AND FM II LIMITERII CIRCUIT Li FIGURE 4 II FM aty An FM receiver has circuit called iimiterit strips off AM-type characteristics signal received before processing signal further AM ThANSMISSION bI/&H VOL 73 FIGURE 5 RA4//v7 TT OFF Loul 4/01-75 FAI TRAAISM 155/OAf OUflU ALWAYS /116A/ 72cXc 7OC5PASS 5AAAD FM NOT CEWTEED 7 xxx 72 7205 iRA NSfr7/T7R 04 RdDUCC3 ADROL PUL ~-5 J FM Pobuc65 Ce~u7ROL PULSES Believe new narrow-band RC systems possible FM transmitter interfere control AM receivr AM transmitter interfere control FM receiver figure alone may tell too muchbut George has very good description what happening months column Read heed amplitude modulation classic commu nications sense either Commercial AM ra dio stations avoid 100% modulation swing ing RE amplitude zero because distorts message causes spatter lets signal appear other places RE band isnt wanted RCnbAM systems switch transmitters crystal-controlled oscillator ON/OFF send control information Information carried analog based length time pulse ON explained before bothered kind distortion Continued page 126 February 1984 39 SAL TFORKII District 3 Symposium Workshop Jan 14-15 1984Sponsored Tusco RC Club Admission $500 y $800 ys Wives Free P-38IBrown Continued oaoe 123 Surface movements should approxi mately follows rudders 3/s-in both ways ailerons /4-in both ways elevator 5/6-in both wayswith little bit uptrim start Aileron response posi tive like full-size aircraft roll rate slow Ailerons rudders needed no trim adjustments elevator model needed bit up-trim offset nose-heaviness Landings Cub-like need full throttle first flight make few landing approaches well before fuel runs low get feel sink rate Dont try come final nose too high keep level down slightly until just before touchdown flair slightly have done some low-speed testing model altitude course hangs stalling surprisingly well youve always wanted try twin boxy add-an-engine designs turn off try racy P-38 Theres nothing like twinon ground especially air Radio Technique/Myers Continued aoe 39 would confuse voice music RC systems designers very concerned spatter however dont actually use ON/OFF switching Instead use shaped tran sition ON OFF ON minimizes spatter Just make things bit complex significant deviations ideal performance hardware both sys tems As consequence ON/OFF signalshaping mentioned above AM trans mitter puts little frequency shift transmitted RF signal time turns signal ON OFF shift FM its minor amount its needed control spatter shift decoded narrow-band FM receiver because re ceiver designed detect exactly kind small shift frequency Reminds Catch 22 doesnt point should point out servos controlled same way send little pulses voltage ON-time pulse determines servo out put shaft position see Fig 2 FM receiver little less ideal too theory ideal FM receiver ampli fies received signals point can clean off incidental AM use its limiting stages see Fig 3 However AM coming RCnbAM transmitter goes way zero also has exactly same configuration valid control signal should able see limiter cant get rid really wanted jam RCnbFM youd hard put find better way using RCnbAM now should grasp RCnbAM transmitter can control RCnbFM receiver amount AM put out RCnbFM transmitter negligible So does RCnbFM transmitter manage control RCnbAM receiver bandwidths RC AM FM sys tems have essentially same characteris tics Without becoming overly technical should able visualize RC sys tems spaced 10 kHz away other Common Carrier systems must neces sity use bandwidths equal less half distance between channel centers Therefore new narrow-band RC sys tems must use bandwidths 5 kHzor lessfor both AM FM systems IF intermediate frequency section RC receiver must designed cut off infor mation sharply slightly before 5 kHz points minimize adjacent-channel interference problems see Fig 4 Now lets take look what happens RCnbFM signal passes through real RCnbAM receiver happiest circumstances center frequency interfering RCnbFM transmitter happens land passband RCnbAM receiver deviated FM signal also lands within passband outputs two signals will equal shown Fig 5a voltage will sent servo wont pulse As consequence no interference control will result QSEE HOT STUFFTVIDEO-TI PS VHS CASSETTES #S 1 2 CLIP THIS COUPON SEND $5500 check MO GET BOTH VHS TAPES PLUS 1 EA 2 oz HOT STUFF 2 oz SUPER T 3 oz HOT SHOT FREE OFFER GOOD IN U S ONLY THRU JUNE 84 PO BOX 836 h4 S MI CA 93062 805 522-0062 126 Model Aviation Reservations Salt Fork Lodge Box 7 Cambridge OH 43725 800 282-7275 DIRECTIONS$54/night double US 22 East tram 177 just north Cambridge AMAIMA4IMACQSPRA Workshops will conducted areas RC including Gliders Gene Shelkey Electric Helicopters Fabricating Scale Parts Ed Wisser Monokoting Ramona Schultz Foam Cutting Bob Wallace other workshops Sigs Dave Brown Mark Ratcliffe Al Seidowski DISTRICT 3 MEETING further information call write Bob Button216343-7906 712 E 4th St Dover OH 44622 1731 6* 45 Street Ft Lauderdale FL 33309 13051 491-61 15 THE LANDING GEAR PEOPLE Tired 1 kit landing gears dcii III biggie property 0 & 0 Engineertug can solve problemil * Custom bout needs & specs guoranteod tit * Strong & durable withstand toighest landiog * 0 & 0 Eugloesriog gear wilt work & keep ysur biggie Ilylog * In otock roplaceweot gear br popular models Byron PIlls Cbniten Eagle LAP 21 Balsa USA J-3 CUB Air Tech Pawnee aid Eugle Nose Big Stick Champ ClIabria II & 0 medeli Soapper Stinger ond Snapper Tii However todays crystals usually ac curate 18 kHz average 075 kHz best worst-case analysis take double value difference between center frequencies RCnbAM transmitter interfering RCnbFM system Now add 3-5 kHz FM deviation believe will find cases deviation will land outside RCnbAM receivers passband Fig Sb As result decoded FM signal will now generate pulses can con trol servoeven though servo hooked AM receiver might led ask dont FM set manufacturers select crystals deviations centered band know might doing would help new FM set avoid interference AM set crystal AM set also perfectly centered band Tolerances being what wouldnt want bet hap pening Repeating what said above its nor mal see FM transmitter controlling AM receiver vice versa cant fly AM FM same channel same time Bob Aberle test new RC systems gets business being RC equipment reviewer will put test airplane up quite high turn other kind transmitter same channel general FM systems seem resist interference better please dont make mistake thinking re sistance absolute test involves slowly collapsing antenna transmitter system ing tested until test airplane throws fit get very busy yanking out test antenna turning off interference Usually FM antenna collapsed excitement starts AM tenna opposite test thing remember always hits other Continued page 130 CHUCK WOOD I-lank Clark5M0 RE5T N PE5TON ~TTY LADV 0$ IVIY GOD YOURE IFVOU SAYSO r GIRLS MEETWELL- DOHAVL TERRIRC 7 WERE ALL FAST IS THIS TME K wboDf CAIAETOSEE CIUCK WOODY4MPLAY0VE AT ROOD FREAKS~LLGETYOU HEADQUARTERSOH MOW UTTERL& SOME OF THE ES 2ACK QUICKY IMAGiNE FOR AMAFANTASTICALLY N MEN HERET LUNCH AwDAND AMGrRIS HAVING MARINE RET0N IGHTFULT -TI-4ERE ARE LOVE TO HAVE YOUHUN&R~ 4 HE LOOKS FOR LUNCI4 /IOw DID MEN HERE JOIN USi9- DELICIOUStHAT OLD 6$L$ /MAlhIK CLAR \lIIt//W~EVER DREAM U a- OUCAME YJET ************* * ******#****** * * * * WANDITTM * *Dealers Invited * * aim year ~1OftCORDJ orOry Stick en Abrasives * *A Keen Machinethat gives esceptienal *sandng central foran excellent finish. * *899 Basic mcI1 flat Wand *ef 6 grits *1 O8~Bailder Special mcI 2 ftat half 4 *reand wand 5 eacn 6 grits *1 295Deluxe includes 3 flat 2 half *raved wandsI buff wanes axe *tO 6 grits * *Additiexal Wands Abrasues availablK * year lecal hebby shap 4 *ADO IS ELMORE tee No i2t41 288 5789 * ox 266 uite Texas 751494 * February 1984 127 IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CID QUADRA010950 Rag 22 QUADRA $10450 Brisighef Ia Flywheel 612450 Rag 22 QUADRA POWER ASSEMBLY ONLY $9450 QUADRA REPAIR 1000 plus pans Jin Masse ERCOUPEPLANS $2395 KIT $23995 Jim Masser TOMAHAWKPLANS 62395 KIT $25995 Jo, Masse 9-BALL TRAINER PLANS $1895 KIT $9995 BALSA BASSWOOD taft sicesl 35% OFF Concept FLEET PLANS $2995 KIT $15095 COWL $1995 FLOATS 36~Il5 scale cores $1795 complete kit $3995 FLOATS 48V scalexmas $2195 complete kit $4795 CECONITE Products 1$% OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN lGodfrayl $2895 STARDUSTER TOO IBrisighetlal N J3 CUB NaIlS $2995 VOLKSPLANE N Chicken Charliel $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2295 Ercoupe $2095 Stearmas $2295 Citabria $2495 J3 Cob $2195 MElDS $2295 Fleet $2195 US Quadra FUEL TANKS16 oa $895 32 sa $795 FIBERGLASS ARROW SHAFTS 5116 32 long 8101000 24-Hour Sarsice d $25Opost*gB Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 VaIloy View Dr Allogany NV 14706 Send S100 Cash Check Stamps 32 Page Tabloid size illustrated DISCOUNT Catalog Sent 1st Class Mail COMET COX FLYLINE FOX GOLDBERG GUILLOWS JETCO K&B PACTRA POLYMER PERFECT SIG- STERLING LLIVAN TOP FLITE & OTHERS PENN VALLEY HOBBY CENTER 837 W Main St LansaIsa194I6 ixisi 55$ iaos 165 0x70 D EHINGE hinge allows control surface removal tools transportation Storage etc PATENTcovei I7IW Scale Appearance InsertSimple Assembly 3 SIZES No Slots No Pins 14-6 $335 38-6 $445 ATTENTION ERS beginner p. written illus trated R/Cer over 50 years model air plane experience Teaches basic model aerodynam ics commonsense manner. covers radio equipment learning fly much Easy understand must R/C modelers library $1195 Please add $100 ordered direct Available hobby shops order direct ACE R/C BOX 5110 HIGGINSVILLE MO 64037 GREAT PLANES MODEL DISTRIBUTOR BOX 725 URBANA ILLINOIS 61801 ZENITH AVIATION BOOKS BOX 14 OSCEOLA WISCONSIN 54020 Radio Technique/Myers Continued fmm paqe 126 under some conditions Thats cant fly FM AM systems same RC channel same time George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 RC Aerobatics/Van Putte Continued paqe 43 flight time limit pilot must still com mence takeoff within three minutes will have no time limit after Did hear big cheer Expert-class fliers option pilot choose up wind downwind direction has eliminated pilot must fly maneuvers actual directions listed maneu ver sequence So much us like perform rolling maneuvers right left exclusive right equal exposure judges has eliminated Contest Directors encouraged provide equal exposure required disqualify flights adverse weather causes unequal ex posure presume Contest Directors will still required provide equal ex posure good weather prevails old rule applauded fliers past does create hardship CDs judges typical two-flight-line contest 40 contestants six rounds possible order provide equal exposure judges hedge adverse weather problems judging set should line first two rounds another set next two means set judges must line six hours time eliminates some judges cant maintain judging quality long viable alternative to have set judges first third rounds another set second fourth rounds Equal exposure front two sets judges will achieved end fourth round another set hardy judges must line last two rounds However equal exposure achieved4 flier think its worth effort new rule have reservations about states Contest Director must set number flights flown before flying begins number may shortened due adverse weatherbut increased rule will limit CDs options Un fortunately very seldom con testants arrive before middle first round much less before flying begins beginning contest CD will forced guess rounds can flown some cases contest will over first day fewer fliers show up expected other hand surge late entries could cause long-running con test new rule changes number flights count final score good because extends reward consistency Now past4 best flight counted two flights flown4 best two counted three flights flown best three count four five flights flown change best four flights will count six flights flown will 130 Model Aviation Rotate EPOXY GLASS COWLS FOR NOSENPVCA SIO MORGAN BALSA USA PLAfl CONCEPT FLEET HOSTETLER RCM TCP4fl SHEBER PIUS & SCALE SUPER CUB FOKKER 0-7 BOEING P42 P-26 P482 F4B4 SPARROW HAWK GEE BEE MOO RIENS TURBULENT CHRIS TEN EAGLE BRISIGHELLAS STAROUSTER II SCALE J3-BI BABY FL YBABY AIRCAMPER PILOT .OURGMANN 7s35 SCALE 7/4 SCALE DECATHALON PIPER PAIB & OTHERS WHEEL PANTS FOR CITABRIA STAROUS TEN II P1775 SKYBOLT LIBER TV SPORT CHRISTEN EAGLE P6 E HAWK STEARMAN STINSON SR-B MULLIGAN & OTHERS 3R4ZED & HEAT-TREATED WIRE GEARS& CABANES LARGE SCALE PLANS AVAILABLE Send $100 latest list supply Modelers fiberglass parts plansWrite call us T 6 D FIBERGLASS SPECIALTIES 30925 BLOcK GARDEN CITY MI 48135 PHONE 313 421-6358 480 S*,4 Woe0*4 V4 WHY m 440W USE *44000PUS 44O00Th4000400044044o 4 40 04 04440444000 0004440404444 TOE 40004E4 000 0444444 440*440/Cm TO 44*04 P44444*440444444/40•LE P044440Th 44440*44410440404404/04 WE NEED YOUR have made videotapes club events especially MALL SHOWS AMAs PR Department would like use future projects will send us tapes will copy return quickly Please send tapes Doug Pratt AMA Public Relations Department 1810 Samuel Morse Drive Reston VA 22090
Edition: Model Aviation - 1984/02
Page Numbers: 38, 39, 122, 123, 126
a loec ni ue George M Myers FIGURE 1 FRE1/EAIFY M 5 kI M9 Cc new narrow-band RC receivers respond transmitted signal somewhat like figure showsexcept real-world hardware doesnt have such sharp square cutoffs z limits RC stands exact legal frequency RC transmitter CC stands frequency Common Canier transmitter Join us month find Out about new RC gear really worksand what difference between familiar AM systems new FM ones AM OFF- NO TRANSMISSION euRSTS o- 72CXJ MN FM FIGURE 2 V L IFT lb 2Xx5 MHj examined what transmissions two RC transmitters looked like oscilloscope youd see something like RC systems send out bursts information AM system top does turning transmitter Off precise intervais FM system lower does abruptly shifting its transmission frequency small amount approximately 005 MHz shown receiver sees operations its decoder translates signals useful informationit tells servos what position move NEW advent new RC frequen cies has added just bunch new frequencies us fly onthe FCC regu lations also allow us use new method radio transmission FM past RC sets have used either CW carrier wave signals switched Off mainly back early days singlechannel rudder-only rubberband-powered escapement systems AM amplitude modulation AM familiar practically everyone worldits what radio stations used until fairly recent times now entertainment radio stations using FM frequency modulation transmission lets us have true high-fidelity sound resistant static Now know cant listen FM radio station AM radio vice versa right thats true same situation must occur FM AM RC gear right Wrong such strange situation going take close look month What going talk about Will AM transmitters fly FM receivers vice versa think very timely question Im addressing direct result letter read ers David Shema AMA 5180 lives Bozeman MT Last month bought new JR Century VII Helicopter radio FM system RC42 ck would have first day new JR field another flier showed up Futaba FP-7GK RC42 AM set Since first far FM set club being curious tried following experiment 1 Turned ON FM transmitter AM receiver Result solid con trol over planethe servo func tions moved around solid controlno glitches no jit ter 2 Turned everything OFF Turned AM transmitter FM receiver Result he solid control over Heliboy 3 Later day flying about 200 feet away turned receiver still solid control Heliboy ground well airplane air 4 When flying done went over house look trans mitter signals oscilloscope 38 Model Aviation hi1416H LOW 0 Iu 0 Sure enough clearly FM typical AM question normal must compliment Mr Shema sys tematically checking through new situa tion keep saying people should make tests what observe few actually Its gratifying meet does emphatic point want make results Mr Shema obtained en tirely normal Commercial AM FM broadcast radios free mutual interference two reasons operate different radio frequencies RF 1 AM 055 thru 160 MHz 2 FM 88 thru 108 MHz 2 use different intermediate frequencies IF 1 AM uses 455 MHz 2 FM uses 107 MHz RC AM FM transmissions same RC channel will interfere another because will using same RE will 50 new channels authorized RC model aircraft Both will also using 455 MHz IF except rare dualconversion sets use 107 MHz well An unthinking few have suggested us ing old RC crystals new FM RC sys tems idea both illegal foolish reason worked hard get away old 7208 etc chan nels because overrun interference FM Both AM FM RC signals really two-valued signals system works varying transmitted signal between RC channel frequency 'something else FM case something else frequency three five kHz above below RC channels crystal-controlled stable frequency very small change AM case shift big y zero Hz same DC OFF see Fig 1 RC narrow-band FM RCnbFM really isnt frequency modulation classic communications sense Its modulation mode Frequency-Shift Keying FSK means deviates steps abruptly frequency other rather swinging more-or-less smoothly within limits deviation range 5 kHz RC would case responding voice music have digital computer tele phone modem know uses FSK putting data telephone line through modem should easy understand RCnbFM really uses digital signal form though infor mation carried analog way length time information-pulse ON represents position control stick/knob/lever RC Narrow-band AM RCnbAM isnt SERVOSRVOSERVOSERVO IZ3 FIGURE servos BC system fed diet voltage pulses receiver/decoder servo knows what position has string pulses uses width pulse detemilne position has commanded assume M1E AM AND FM II LIMITERII CIRCUIT Li FIGURE 4 II FM aty An FM receiver has circuit called iimiterit strips off AM-type characteristics signal received before processing signal further AM ThANSMISSION bI/&H VOL 73 FIGURE 5 RA4//v7 TT OFF Loul 4/01-75 FAI TRAAISM 155/OAf OUflU ALWAYS /116A/ 72cXc 7OC5PASS 5AAAD FM NOT CEWTEED 7 xxx 72 7205 iRA NSfr7/T7R 04 RdDUCC3 ADROL PUL ~-5 J FM Pobuc65 Ce~u7ROL PULSES Believe new narrow-band RC systems possible FM transmitter interfere control AM receivr AM transmitter interfere control FM receiver figure alone may tell too muchbut George has very good description what happening months column Read heed amplitude modulation classic commu nications sense either Commercial AM ra dio stations avoid 100% modulation swing ing RE amplitude zero because distorts message causes spatter lets signal appear other places RE band isnt wanted RCnbAM systems switch transmitters crystal-controlled oscillator ON/OFF send control information Information carried analog based length time pulse ON explained before bothered kind distortion Continued page 126 February 1984 39 SAL TFORKII District 3 Symposium Workshop Jan 14-15 1984Sponsored Tusco RC Club Admission $500 y $800 ys Wives Free P-38IBrown Continued oaoe 123 Surface movements should approxi mately follows rudders 3/s-in both ways ailerons /4-in both ways elevator 5/6-in both wayswith little bit uptrim start Aileron response posi tive like full-size aircraft roll rate slow Ailerons rudders needed no trim adjustments elevator model needed bit up-trim offset nose-heaviness Landings Cub-like need full throttle first flight make few landing approaches well before fuel runs low get feel sink rate Dont try come final nose too high keep level down slightly until just before touchdown flair slightly have done some low-speed testing model altitude course hangs stalling surprisingly well youve always wanted try twin boxy add-an-engine designs turn off try racy P-38 Theres nothing like twinon ground especially air Radio Technique/Myers Continued aoe 39 would confuse voice music RC systems designers very concerned spatter however dont actually use ON/OFF switching Instead use shaped tran sition ON OFF ON minimizes spatter Just make things bit complex significant deviations ideal performance hardware both sys tems As consequence ON/OFF signalshaping mentioned above AM trans mitter puts little frequency shift transmitted RF signal time turns signal ON OFF shift FM its minor amount its needed control spatter shift decoded narrow-band FM receiver because re ceiver designed detect exactly kind small shift frequency Reminds Catch 22 doesnt point should point out servos controlled same way send little pulses voltage ON-time pulse determines servo out put shaft position see Fig 2 FM receiver little less ideal too theory ideal FM receiver ampli fies received signals point can clean off incidental AM use its limiting stages see Fig 3 However AM coming RCnbAM transmitter goes way zero also has exactly same configuration valid control signal should able see limiter cant get rid really wanted jam RCnbFM youd hard put find better way using RCnbAM now should grasp RCnbAM transmitter can control RCnbFM receiver amount AM put out RCnbFM transmitter negligible So does RCnbFM transmitter manage control RCnbAM receiver bandwidths RC AM FM sys tems have essentially same characteris tics Without becoming overly technical should able visualize RC sys tems spaced 10 kHz away other Common Carrier systems must neces sity use bandwidths equal less half distance between channel centers Therefore new narrow-band RC sys tems must use bandwidths 5 kHzor lessfor both AM FM systems IF intermediate frequency section RC receiver must designed cut off infor mation sharply slightly before 5 kHz points minimize adjacent-channel interference problems see Fig 4 Now lets take look what happens RCnbFM signal passes through real RCnbAM receiver happiest circumstances center frequency interfering RCnbFM transmitter happens land passband RCnbAM receiver deviated FM signal also lands within passband outputs two signals will equal shown Fig 5a voltage will sent servo wont pulse As consequence no interference control will result QSEE HOT STUFFTVIDEO-TI PS VHS CASSETTES #S 1 2 CLIP THIS COUPON SEND $5500 check MO GET BOTH VHS TAPES PLUS 1 EA 2 oz HOT STUFF 2 oz SUPER T 3 oz HOT SHOT FREE OFFER GOOD IN U S ONLY THRU JUNE 84 PO BOX 836 h4 S MI CA 93062 805 522-0062 126 Model Aviation Reservations Salt Fork Lodge Box 7 Cambridge OH 43725 800 282-7275 DIRECTIONS$54/night double US 22 East tram 177 just north Cambridge AMAIMA4IMACQSPRA Workshops will conducted areas RC including Gliders Gene Shelkey Electric Helicopters Fabricating Scale Parts Ed Wisser Monokoting Ramona Schultz Foam Cutting Bob Wallace other workshops Sigs Dave Brown Mark Ratcliffe Al Seidowski DISTRICT 3 MEETING further information call write Bob Button216343-7906 712 E 4th St Dover OH 44622 1731 6* 45 Street Ft Lauderdale FL 33309 13051 491-61 15 THE LANDING GEAR PEOPLE Tired 1 kit landing gears dcii III biggie property 0 & 0 Engineertug can solve problemil * Custom bout needs & specs guoranteod tit * Strong & durable withstand toighest landiog * 0 & 0 Eugloesriog gear wilt work & keep ysur biggie Ilylog * In otock roplaceweot gear br popular models Byron PIlls Cbniten Eagle LAP 21 Balsa USA J-3 CUB Air Tech Pawnee aid Eugle Nose Big Stick Champ ClIabria II & 0 medeli Soapper Stinger ond Snapper Tii However todays crystals usually ac curate 18 kHz average 075 kHz best worst-case analysis take double value difference between center frequencies RCnbAM transmitter interfering RCnbFM system Now add 3-5 kHz FM deviation believe will find cases deviation will land outside RCnbAM receivers passband Fig Sb As result decoded FM signal will now generate pulses can con trol servoeven though servo hooked AM receiver might led ask dont FM set manufacturers select crystals deviations centered band know might doing would help new FM set avoid interference AM set crystal AM set also perfectly centered band Tolerances being what wouldnt want bet hap pening Repeating what said above its nor mal see FM transmitter controlling AM receiver vice versa cant fly AM FM same channel same time Bob Aberle test new RC systems gets business being RC equipment reviewer will put test airplane up quite high turn other kind transmitter same channel general FM systems seem resist interference better please dont make mistake thinking re sistance absolute test involves slowly collapsing antenna transmitter system ing tested until test airplane throws fit get very busy yanking out test antenna turning off interference Usually FM antenna collapsed excitement starts AM tenna opposite test thing remember always hits other Continued page 130 CHUCK WOOD I-lank Clark5M0 RE5T N PE5TON ~TTY LADV 0$ IVIY GOD YOURE IFVOU SAYSO r GIRLS MEETWELL- DOHAVL TERRIRC 7 WERE ALL FAST IS THIS TME K wboDf CAIAETOSEE CIUCK WOODY4MPLAY0VE AT ROOD FREAKS~LLGETYOU HEADQUARTERSOH MOW UTTERL& SOME OF THE ES 2ACK QUICKY IMAGiNE FOR AMAFANTASTICALLY N MEN HERET LUNCH AwDAND AMGrRIS HAVING MARINE RET0N IGHTFULT -TI-4ERE ARE LOVE TO HAVE YOUHUN&R~ 4 HE LOOKS FOR LUNCI4 /IOw DID MEN HERE JOIN USi9- DELICIOUStHAT OLD 6$L$ /MAlhIK CLAR \lIIt//W~EVER DREAM U a- OUCAME YJET ************* * ******#****** * * * * WANDITTM * *Dealers Invited * * aim year ~1OftCORDJ orOry Stick en Abrasives * *A Keen Machinethat gives esceptienal *sandng central foran excellent finish. * *899 Basic mcI1 flat Wand *ef 6 grits *1 O8~Bailder Special mcI 2 ftat half 4 *reand wand 5 eacn 6 grits *1 295Deluxe includes 3 flat 2 half *raved wandsI buff wanes axe *tO 6 grits * *Additiexal Wands Abrasues availablK * year lecal hebby shap 4 *ADO IS ELMORE tee No i2t41 288 5789 * ox 266 uite Texas 751494 * February 1984 127 IN STOCK FOR IMMEDIATE SHIPMENT New 30 CID QUADRA $20950 New 22 CID QUADRA010950 Rag 22 QUADRA $10450 Brisighef Ia Flywheel 612450 Rag 22 QUADRA POWER ASSEMBLY ONLY $9450 QUADRA REPAIR 1000 plus pans Jin Masse ERCOUPEPLANS $2395 KIT $23995 Jim Masser TOMAHAWKPLANS 62395 KIT $25995 Jo, Masse 9-BALL TRAINER PLANS $1895 KIT $9995 BALSA BASSWOOD taft sicesl 35% OFF Concept FLEET PLANS $2995 KIT $15095 COWL $1995 FLOATS 36~Il5 scale cores $1795 complete kit $3995 FLOATS 48V scalexmas $2195 complete kit $4795 CECONITE Products 1$% OFF Sig J3 CUB KIT $12495 PLANS SUPER STEARMAN lGodfrayl $2895 STARDUSTER TOO IBrisighetlal N J3 CUB NaIlS $2995 VOLKSPLANE N Chicken Charliel $2395 COCKPIT KITS Tomahawk F4U1 Spitfire $2295 Ercoupe $2095 Stearmas $2295 Citabria $2495 J3 Cob $2195 MElDS $2295 Fleet $2195 US Quadra FUEL TANKS16 oa $895 32 sa $795 FIBERGLASS ARROW SHAFTS 5116 32 long 8101000 24-Hour Sarsice d $25Opost*gB Send Bank Check Money Order JIM MESSERS QUALITY MODEL PRODUCTS 106 VaIloy View Dr Allogany NV 14706 Send S100 Cash Check Stamps 32 Page Tabloid size illustrated DISCOUNT Catalog Sent 1st Class Mail COMET COX FLYLINE FOX GOLDBERG GUILLOWS JETCO K&B PACTRA POLYMER PERFECT SIG- STERLING LLIVAN TOP FLITE & OTHERS PENN VALLEY HOBBY CENTER 837 W Main St LansaIsa194I6 ixisi 55$ iaos 165 0x70 D EHINGE hinge allows control surface removal tools transportation Storage etc PATENTcovei I7IW Scale Appearance InsertSimple Assembly 3 SIZES No Slots No Pins 14-6 $335 38-6 $445 ATTENTION ERS beginner p. written illus trated R/Cer over 50 years model air plane experience Teaches basic model aerodynam ics commonsense manner. covers radio equipment learning fly much Easy understand must R/C modelers library $1195 Please add $100 ordered direct Available hobby shops order direct ACE R/C BOX 5110 HIGGINSVILLE MO 64037 GREAT PLANES MODEL DISTRIBUTOR BOX 725 URBANA ILLINOIS 61801 ZENITH AVIATION BOOKS BOX 14 OSCEOLA WISCONSIN 54020 Radio Technique/Myers Continued fmm paqe 126 under some conditions Thats cant fly FM AM systems same RC channel same time George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 RC Aerobatics/Van Putte Continued paqe 43 flight time limit pilot must still com mence takeoff within three minutes will have no time limit after Did hear big cheer Expert-class fliers option pilot choose up wind downwind direction has eliminated pilot must fly maneuvers actual directions listed maneu ver sequence So much us like perform rolling maneuvers right left exclusive right equal exposure judges has eliminated Contest Directors encouraged provide equal exposure required disqualify flights adverse weather causes unequal ex posure presume Contest Directors will still required provide equal ex posure good weather prevails old rule applauded fliers past does create hardship CDs judges typical two-flight-line contest 40 contestants six rounds possible order provide equal exposure judges hedge adverse weather problems judging set should line first two rounds another set next two means set judges must line six hours time eliminates some judges cant maintain judging quality long viable alternative to have set judges first third rounds another set second fourth rounds Equal exposure front two sets judges will achieved end fourth round another set hardy judges must line last two rounds However equal exposure achieved4 flier think its worth effort new rule have reservations about states Contest Director must set number flights flown before flying begins number may shortened due adverse weatherbut increased rule will limit CDs options Un fortunately very seldom con testants arrive before middle first round much less before flying begins beginning contest CD will forced guess rounds can flown some cases contest will over first day fewer fliers show up expected other hand surge late entries could cause long-running con test new rule changes number flights count final score good because extends reward consistency Now past4 best flight counted two flights flown4 best two counted three flights flown best three count four five flights flown change best four flights will count six flights flown will 130 Model Aviation Rotate EPOXY GLASS COWLS FOR NOSENPVCA SIO MORGAN BALSA USA PLAfl CONCEPT FLEET HOSTETLER RCM TCP4fl SHEBER PIUS & SCALE SUPER CUB FOKKER 0-7 BOEING P42 P-26 P482 F4B4 SPARROW HAWK GEE BEE MOO RIENS TURBULENT CHRIS TEN EAGLE BRISIGHELLAS STAROUSTER II SCALE J3-BI BABY FL YBABY AIRCAMPER PILOT .OURGMANN 7s35 SCALE 7/4 SCALE DECATHALON PIPER PAIB & OTHERS WHEEL PANTS FOR CITABRIA STAROUS TEN II P1775 SKYBOLT LIBER TV SPORT CHRISTEN EAGLE P6 E HAWK STEARMAN STINSON SR-B MULLIGAN & OTHERS 3R4ZED & HEAT-TREATED WIRE GEARS& CABANES LARGE SCALE PLANS AVAILABLE Send $100 latest list supply Modelers fiberglass parts plansWrite call us T 6 D FIBERGLASS SPECIALTIES 30925 BLOcK GARDEN CITY MI 48135 PHONE 313 421-6358 480 S*,4 Woe0*4 V4 WHY m 440W USE *44000PUS 44O00Th4000400044044o 4 40 04 04440444000 0004440404444 TOE 40004E4 000 0444444 440*440/Cm TO 44*04 P44444*440444444/40•LE P044440Th 44440*44410440404404/04 WE NEED YOUR have made videotapes club events especially MALL SHOWS AMAs PR Department would like use future projects will send us tapes will copy return quickly Please send tapes Doug Pratt AMA Public Relations Department 1810 Samuel Morse Drive Reston VA 22090