User Manual in PDF - All Spectrum Electronics
Contents
1. 5 FM30 PC Board Parts Layout 11 FM30 Parts List 12 FM30 PC Board Assembly Steps 14 FM30 Schematic Centerfold 20 Appendix A FCC Rules and Info 31 Appendix B sss 33 SUMMA ette eene Ene de 35 Warranty sese elas 39 REQUIRED TOOLS e Soldering Iron WLC100 e Thin Rosin Core Solder RTS12 e Needle Nose Pliers PTS401 e Small Diagonal Cutters PTS400 ADDITIONAL SUGGESTED ITEMS e Helping Hands Holder for PC Board Parts HH3 e Desoldering Braid RTSO08 TOTAL SOLDER POINTS 540 ESTIMATED ASSEMBLY TIME Beginner 12 hrs Intermediate 6 hrs Advanced 4 hrs RAMSEY ELECTRONICS INC 590 Fishers Station Drive Victor New York 14564 Phone 585 924 4560 Fax 585 924 4555 Manual Price Only 5 00 Ramsey Publication No FM30 Assembly and Instruction manual for RAMSEY MODEL NO FM30 DIGITAL FM STEREO TRANSMITTER KI2. Install C27 a 100 electrolytic capacitor Remember that the long Install C32 10nF or 0 01uF ceramic disc capacitor marked 103 Install R29 1k ohm resistor brown black red Install C37 0 10 ceramic disc capacitor marked 104 Install C39 3300pF ceramic disc capacitor marked 332 FM30 17 O O u 0 E E E g 0 uuuau 67 Install C40 150pF ceramic disc capacitor marked 151 68 Install C26 33pF ceramic disc capacitor marked 33 69 Install C22 18pF ceramic disc capacitor marked 18 70 Install X1 the 7 6MHz crystal marked 7 600 Place the leads in the holes then bend the part over so that it fits in the silkscreen outline Solder both leads 71 Install C56 20pF variable capacitor red body with adjustment screw 72 Install R32 3 3k ohms orange orange red 73 Install C62 0 10 ceramic disc capacitor marked 104 74 Install L4 2 2uH inductor green body with red red gold silver bands 75 Install C11 100 electrolytic capacitor Again be careful to follow the silkscreen when installing 76 Install L5 2 2uH inductor green body with red red gold silver bands 77 Install C55 10nF or 0 01uF ceramic disc capacitor marked 103 78 Let s move toward the back of the board near J9 and install L6 2 2uH inductor green body with red red gold silver bands 79 Install C67 47pF ceramic disc capacitor marked 47 80 Install L
3. 4 7k ohm resistor yellow violet red 19 Install C54 560pF ceramic disc capacitor marked 561 0 20 Install C51 10 electrolytic capacitor Electrolytic caps have a polar ity and must be installed correctly in order to work and in some cases in order not to blow up when power is applied You ll note that the legs of the part are different lengths and there is a stripe or band down one side of the capacitor that corresponds to the shorter of the two leads This is the negative side of the cap The silkscreen and Parts Layout Diagram will show where the positive lead is to be placed by a sign on the board Orient the part with the longer lead in the hole and solder the part in O 21 Install R44 100 ohms brown black brown O 22 Install R30 56k ohms green blue orange FM30 15 0 a O O O O 0 0 0 0 23 Install C13 100uF electrolytic capacitor Remember to orient the longer positive lead with the sign on the board before soldering 24 Install C44 100pF marked 101 25 Install R24 2 2k ohms red red red This resistor is installed in standup fashion simply place one lead of the part into the hole marked with a circle then bend the other lead over to fit in the other hole for R24 Solder as usual 26 Install C45 560pF disc capacitor marked 561 27 Install R26 56k ohm resistor green blue
4. 7 enough for our multiplex signal to still be transmitted but the tuning signals to not be transmitted The parts in this section are carefully chosen for best operation in audio performance but have the drawback of being really slow to tune from one end of the dial to the other To speed it up would mean to loose some of the low frequency response of our audio signal In the case of the FM30 we have made the PLL very slow to pass low frequency audio very well for best quality You will just have to be patient when you turn the unit on before you can begin transmitting Since most of these transmitters are left running all the time on the same frequency we knew this wouldn t be a problem for most of you Now there are some other tricks going on in the PLL and the VCO circuit which you may wonder about What is the purpose of Q4 Well because we are tuning a broad range of frequencies in the FM30 the VCO s tuning sensitivity vs frequency can change quite a lot Without this part a properly adjusted 75kHz FM stereo signal at 108 1MHz may be 250kHz by the time you get down to 88 1MHz This is unacceptable because it would be very hard to know when you were over modulating without test equipment This would also render the quality of signal detector useless that we have on the audio inputs Q4 corrects the tuning sensitivity by acting like a variable pot based on the tuning voltage As the tuning voltage goes down Q4 is turned on more and
5. in the next section You don t want to find out too late that an electrolytic ca pacitor diode or IC was installed backwards or that you have a damaging solder bridge somewhere Use the Parts Layout Diagram to help you deter mine which connections are correct and which are suspect if you have any doubts at all OK let s fire this baby up and see what it will do FM30 25 FM30 SETUP It s time to set up and test your FM30 then get on the air You ll need the case power supply whip antenna a small screwdriver or diddle stick and a line level audio source such as a CD player or computer sound card Let s go FM30 operation is about as simple as it gets The SETUP button cycles through the various screens and the UP DOWN button adjusts the value on the particular screen First of all if you haven t already adjust the contrast pot R1 by turning the orange top to the right clockwise as you re looking at it until it s about half way to its stopping point If you don t do this first you ll turn the kit on and hear the beep but see nothing on the display at which point panic usually sets in along with the assumption that you ve made a construction error Let s skip all that and do a first adjustment now then you can set the pot to your individual contrast tastes later Next slide the kit into the case You MUST have the kit in the case or it will not work properly this is because of that weird trace on the back of t
6. 104 C12 14 17 24 36 37 43 48 57 62 10pF ceramic disc capacitor marked 10 C2 18pF ceramic disc capacitor marked 18 C22 33pF ceramic disc capacitor marked 33 C26 47nF or 0 0470 ceramic disc capacitor marked 473 C34 470 ceramic disc capacitors marked 47 C67 70 75pF ceramic disc capacitor marked 75 C66 100pF ceramic disc capacitors marked 101 C16 25 28 44 50 150pF ceramic disc capacitors marked 151 C31 40 560pF ceramic disc capacitors marked 561 C23 45 52 54 3300pF ceramic disc capacitors marked 332 C30 39 1000 electrolytic capacitors C13 38 12100 electrolytic capacitors C1 9 10 11 15 21 27 29 41 42 47 51 20pF trim cap red body with adjustment screw C56 ISCELLANEOUS 28 pin socket for U1 PCB Mounted BNC connector J9 DPDT Power switch S1 2 20 inductors green body red red gold silver L1 2 3 4 5 6 4 turn air core inductors L8 9 2 1mm center post positive power jack J3 RCA audio jacks J8 J10 Mini speaker SP1 7 6MHz Crystal Marked 7 600 X1 Switch cap Case Top amp Bottom screws for case Front and rear panels 15VDC power supply Whip antenna FM30 11 SURFACE MOUNT PARTS PREINSTALLED BBY40 Varactor diode SOT23 package marked S2 D5 LM2940CS 12 12VDC low dropout regulator VR1 153 172 Pin Diode SOT package B and E marking D8 0 10 ceramic surface mount capacitors C18 35 4700 ceramic surface mount capacitors C19 20 BH
7. a quality of signal value for you In our case the comparator is designed to detect peaks over 75kHz of deviation which is the standard bandwidth used by radio stations If you run the volume up too high on the FM30 the comparator reference level is surpassed often the micro counts this and an indicator on the display will show a poor quality of signal indication Speaking of the reference voltage all of the analog circuitry needs to be biased up at 1 2 of the supply voltage so that your audio signal has the greatest possible dynamic range We would like the analog signals to be able to go all the way from OV to 5V and in order to do this with minimal distortion we need 2 5V This bias voltage is generated with a simple resistor divider consisting of R22 and R24 and then noise filtered with C42 and C43 This voltage is then amplified with U5 D which is set at a gain of 1 and then distributed to the rest of the analog circuitry This leads us to the next important part of the circuit the microcontroller This section is essentially the brains of the show The microcontroller does several things all of the time it checks for button presses it counts the quality of signal information it measures RF power and it updates the display The microcontroller also does important tasks like converting the frequency value to text on the display that you can read and signals that the stereo modulator FM30 6 IC needs to go to that fre
8. diode This part has a banded end that must be lined up with the band on the silkscreen and Parts Layout Diagram 103 Install SP1 the mini speaker You ll see a sign on one side of the part and the same sign on the board Line these two up and solder the part 104 Install R31 1k ohms brown black red 105 Install R10 4 7 ohms yellow violet red 106 Install R5 4 7k ohms yellow violet red 107 Install C12 1nF or 0 10 ceramic disc capacitor marked 104 108 Install C15 10uF electrolytic This one s a little weird because the sign is inside the C of the silkscreen but it s there so follow it for orienta tion 109 Install R39 1k ohms brown black red 110 Install C34 47nF or 0 0470 ceramic disc capacitor marked 473 111 Install R23 47k ohms yellow violet orange 112 Install R20 180 ohms brown grey brown 113 Install R21 3 3k ohm resistor orange orange red FM30 19 FM30 SCHEMATIC CENTER FM30 20 FM30 21 O 114 Install C33 1nF or 0 0010 ceramic disc capacitor marked 102 O 115 Install Q3 2N3904 NPN transistor Follow the flat side on the part and the Layout Diagram for correct placement O 116 Next install Q2 another 2N3904 NPN transistor Again orient the part using the flat side of the transistor O 117 Install R17 4 7k ohms yellow violet red Q 118 Install C24 0 10 ceramic disc capacitor marked 104 O 119 Install
9. more which in turn allows less and less of the multiplex signal that is injected into the VCO from pin 5 of U3 to reach the VCO It is a great little compensation circuit which keeps our signal within 10kHz of error across the band Now that we have our locked frequency and our multiplexed signal added to it we want to get the level up to where we can transmit it The level directly out of U3 on pin 11 is small just enough to cover a room so we need to boost it a little U8 is a high gain amplifier which will get up the level for us so the FM30 has a little more oomph However we don t want too much oomph where we don t need it so before the final amp we have D8 which is another special variety of diode called a pin diode This diode has a neat way of working like a variable RF resistor As you put more and more current through it more and more RF will pass through it too To vary the current through D8 we have U7 which is a digital to analog converter This will generate from 0 5 volts in 256 steps and in doing so will drive D8 with 256 steps of current control which gives us the ability to control output level quite a bit L5 and C62 prevent RF from getting back into the gain control of U7 and messing it up The higher level RF out of U8 is then sent through a low pass RF filter to reduce harmonics and finally to the output jack where you would connect an antenna L6 is simply to provide a DC path to ground in case of any s
10. orange 28 Install R28 27k ohms red violet orange 29 Install R27 3 3k ohm resistor orange orange red 30 Install R11 10k ohm resistor brown black orange 31 Install C43 0 10 ceramic disc capacitor marked 104 32 Install C42 100 electrolytic capacitor Remember to watch the polar ity when installing 33 Install R22 2 2k ohms red red red 34 Install CA7 10uF electrolytic Do have to remind you about the polar ity again No I didn t think so 35 Install C17 0 10 ceramic disc capacitor marked 104 36 Install C49 10nF or 0 010 ceramic disc capacitor marked 103 37 Install C57 0 10 ceramic disc capacitor marked 104 38 Install C9 10uF electrolytic cap Remember polarity 39 Install VR2 78L05 marked LM78L 095 Bend the center lead out and place the flat side as shown on the silkscreen Solder all three leads 40 Install C53 10nF or 0 01uF ceramic disc capacitor marked 103 41 Install C10 10uF electrolytic cap Check placement before soldering 42 Install C1 10uF electrolytic capacitors below and to the right of C10 It s another electrolytic but you re an old pro at these by now so won t remind you to be sure to line up the longer lead with the hole marked 43 Install R2 10k ohm resistor brown black orange 44 Install C2 the only 10pF capacitor marked 10 FM30 16 0 45 Install C14 0 10 ceramic disc capacitor marked 104 Well we
11. 1415F Stereo Modulator IC U3 10K ohm surface mount resistors marked 103 R12 13 GAL5 DC 8GHz monolithic RF amplifier U8 Marked o5 naaa AN NN RAMSEY Learn As You Build KIT ASSEMBLY You ll get the best results with your hobby kit if you practice good soldering techniques e Use a 25 watt soldering pencil with a clean sharp tip preferably a tempera ture regulated iron but a standard 25W will do Useonly rosin core solder intended for electronics use e Use bright lighting a magnifying lamp or bench style magnifier may be helpful e Do your work in stages taking breaks to check your work Carefullybrush away wire cuttings so they don t lodge between solder connections We have a two fold strategy for the order of the kit assembly steps First we install parts in physical relationship to each other so there s minimal chance of inserting wires into wrong holes Second whenever possible we install in an order that fits our Learn As You Build Kit building philosophy This entails de scribing the circuit that you are building instead of just blindly installing compo nents We hope that this will not only make assembly of our kits easier but help you to understand the circuit you re constructing For each part our word Install always means these steps 1 Pick the correct part value to start with 2 Insert it into the correct PC board location 3 Orient it correctly follow the PC board drawing and the w
12. 9 4 turn air coil 81 Install C66 75pF ceramic disc capacitor marked 75 82 Install L8 the other 4 turn air coil 83 Install C70 47pF ceramic disc capacitor marked 47 The caps and coils you just installed are the output filter for the kit 84 Install C69 1nF or 0 001uF ceramic disc capacitor marked 102 85 Install R34 120 ohm 1 2 watt resistor brown red brown This part is easy to recognize because it s larger than the other resistors 86 Install C21 100 electrolytic cap Yes watch your polarity 87 Install C46 1nF or 0 0010 ceramic disc capacitor marked 102 88 Install R35 4 7 ohms yellow violet gold 89 Install C68 1nF or 0 001uF ceramic disc capacitor marked 102 FM30 18 a Q UO O O O 90 Install R36 1k ohms brown black red 91 Install R37 1k ohms brown black red 92 Install C41 10uF electrolytic Remember that polarity is still important 93 Install C3 10nF or 0 010 ceramic disc capacitor marked 103 94 Install C30 3300pF marked 332 95 Install C31 150pF marked 151 96 Install R18 20k ohms red black orange 97 Install C16 100pF capacitor marked 101 98 Install R25 47k ohms yellow violet orange 99 Install C48 0 10 ceramic disc capacitor marked 104 101 Install R9 270 ohms red violet brown 102 Install D3 1N4148 small signal switching
13. C38 100 electrolytic capacitor Just as you did with all the others follow the sign on the board so you ll know how to install this part Now we ll place some of the larger parts the jacks and switches then we ll move on to the smaller front panel PC board O 120 Since we re in the area install S1 the DPDT power switch Make sure it is seated flat on the PC board before soldering O 121 Moving on to the back of the board install J3 the 2 1mm center post positive power jack Again be sure the part is flat before soldering O 122 Install J10 one of the RCA jacks O 123 Install J8 the other RCA jack O 124 Install J9 the PCB mounted BNC connector Take a look over your PC board and check for unsoldered components or anything that looks less than perfect You ll have to be sure everything is right before moving on to the small front panel board because once we re finished with that we ll be firing this kit up You ll want to be confident that nothing will burn up or blow up once power is applied O F1 On the front panel PC board install C4 10nF or 0 010 ceramic disc capacitor marked 103 O F2 Next we ll install R1 the 10k ohm trim pot Orange top marked 103 It only fits in the board one way however we re going to place it on the back side of the board the side you ve been soldering to so far This is so that you can adjust the contrast without pulling the board out of the case Simply place it into th
14. DIGITAL FM STEREO TRANSMITTER KIT Ramsey Electronics Model No FM30 A new and improved version of our popular stereo transmitter kits the FM30 is an ideal upgrade for improved performance and ease of use With a low noise design and a metal case the FM30 suffers from much less interference for a better S N ratio The FM30 also has full digital front panel control of output power volume balance stereo mono and frequency e Synthesized 87 9MHz to 108 1MHz for no frequency drift Direct digital input of frequency no jumpers or DIP switches e Designed for extruded rugged metal case all lines have RF chokes and fully regulated for the cleanest sounding low noise performance yet e BNC style RF output for easy reliable connections e Fully digitally controlled transmit power for custom coverage capabilities e Digital volume and balance controls for easy audio level adjustments Runs from 13 8 16VDC includes 15V DC adapter e Quality of signal indicator lets you know when you have a good signal or over modulated signal Lets you know when to turn it up or down e Great for schools health clubs yard casting drive in movie theaters haunted rides amusement parks churches etc PARTIAL LIST OF AVAILABLE KITS RAMSEY TRANSMITTER KITS e FM10A FM25B FM30 FM Stereo Transmitters e FM100B FM35 Professional FM Stereo Transmitters e AM1 AM25 AM Broadcast Band Transmitters KIT 8 RAMSE
15. DO NOT send a separate letter include all correspondence with the unit Please do not include your own hardware such as non Ramsey cabinets knobs cables external battery packs and the like Ramsey Electronics Inc reserves the right to refuse repair on ANY item in which we find excessive problems or damage due to construction methods To assist customers in such situations Ramsey Electronics Inc reserves the right to solve their needs on a case by case basis The repair is 50 00 per hour regardless of the cost of the kit Please understand that our technicians are not volunteers and that set up testing diagnosis repair and repacking and paperwork can take nearly an hour of paid employee time on even a simple kit Of course if we find that a part was defective in manufacture there will be no charge to repair your kit But please realize that our technicians know the difference between a defective part and parts burned out or damaged through improper use or assembly 4 REFUNDS You are given ten 10 days to examine our products If you are not satisfied you may return your unassembled kit with all the parts and instructions and proof of purchase to the factory for a full refund The return package should be packed securely Insurance is recommended Please do not cause needless delays read all information carefully FM30 39 TABLE OF CONTENTS IntroductiON sss 4 Circuit Description
16. Nn 5 FM30 Parts List 10 Learn as you Bulild 12 FM30 PC Board Parts Layout 13 FM30 PC Board Assembly Steps 14 FM30 Schematic Centerfold 20 FM30 Setup sss 26 Antenna ldeas 29 Appendix A FCC Rules and Info 31 Appendix B 33 SUMMARY nesters keke 35 Warranty titt ea 39 RAMSEY ELECTRONICS INC 590 Fishers Station Drive AG 23 Victor New York 14564 Phone 585 924 4560 f ciTISBLJ Fax 666 924 4555 www ramseykits com FM30e 3 INTRODUCTION The Ramsey FM30 is a true SYNTHESIZED STEREO FM broadcast transmitter which any person may build and use in accordance with the rules of their nation s telecommunications authority For U S residents that authority is the Federal Communications Commission FCC The FM30 s low power broadcasting capability and other practical uses can be fun and interesting for people of all ages but the FM30 is not a toy We will refer to the FCC regulations frequently in this manual and provide you with some information necessary to enjoy the FM30 s capabilities in accordance with the law Typical uses for the FM30 include the following e Extension of home stereo system and computer audio without wires e Listening aid for auditoriums churches e Student operated school radi
17. T DESCRIPTION We will begin by talking about the new and improved power supply section of the FM30 First off take a look at L1 C8 and C7 Does that look like anything familiar That is a low pass filter designed to remove any RF from leaving the power jack from the FM30 but more importantly from it entering back in RF can easily get into power regulators and other components and cause them to flake out as we call it The leads to hum and excessive noise in some cases and can be very hard to remedy without these filters D1 is designed to protect you in the unlikely event that power is connected in reverse polarity The diode is placed in line with the power Since a diode can only conduct in one direction it prevents a reversed power supply from damaging your new FM30 We figured the addition of a 5 cent part was worth the peace of mind C5 is another part used to reduce RF interference C13 is used to smooth any ripple there may be on the input to VR1 a 12VDC low dropout regulator You may ask what does low dropout mean No it doesn t mean the regulator was made by a bunch of kids from a privileged school it means that it can regulate lower voltages than it s non low dropout versions can In this case to regulate to 12V VR1 only needs about 0 8V across it this means it can regulate 12 8V and up C9 is used in conjunction with VR1 for good regulation of the 12V The 12 is then fed to VR2 a standard 5V regulator This simpl
18. Y RECEIVER KITS SZ X e FR1 FM Broadcast Receiver 0 SS e ARA Aircraft Band Receiver UN 24 ANNA e SR2 Shortwave Receiver T O SN P e AA7 Active Antenna 0 annos SA e SC1 Shortwave Converter Wis 2 d i Wigs 98607 RAMSEY HOBBY KITS Nae 21 f RAMSEY HOBBY KITS We e SG7 Personal Speed Radar ANS e SS70C Speech Scrambler Descrambler ys 2 ey e TT1 Telephone Recorder THE woe e SP1 Speakerphone e MD3 Microwave Motion Detector e PH14 Peak hold Meter e LC1 Inductance Capacitance Meter RAMSEY AMATEUR RADIO KITS e HR Series HF All Mode Receivers e DDF1 Doppler Direction Finder Kit e QRP Series HF CW Transmitters e CW7 CW Keyer e QRP Power Amplifiers RAMSEY MINI KITS Many other kits are available for hobby school scouts and just plain FUN New kits are always under development Write or call for our free Ramsey catalog FM30 Digital FM Stereo Transmitter Kit Ramsey Electronics publication No FM30 Rev 1 4 October 2004 COPYRIGHT 2004 by Ramsey Electronics Inc 590 Fishers Station Drive Victor New York 14564 All rights reserved No portion of this publication may be copied or duplicated without the written permission of Ramsey Electronics Inc Printed in the United States of America FM30 2 Ramsey Publication No FM30 Manual Price Only 5 00 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR DIGITAL FM STEREO TRANSMITTER KIT TABLE OF CONTENTS Introduction sss 4 Circuit DescriptiO
19. ajor sections of the 88 108 MHz band are 88 MHz each side 2 7 feet 5 4 feet total 98 MHz each side 2 4 feet 4 8 feet total 108 MHz each side 2 2 feet 4 4 feet total You can see that there s not a great difference in antenna length from 88 to 107 MHz Some antenna designers have the view that an approximate di pole such as 2 5 ft on a side will do fine while others believe it is worth the effort to calculate the length for your exact frequency using the simple formula of Length of one side in feet 234 Frequency in MHz FM30 29 If the dipole is installed vertically the end connected to the center conductor of the coax should be the upper higher end If young children will be around the set up a flexible wire antenna is preferable rather than rigid tubing A ground plane antenna can be quite effective A ground plane consists of one vertical element the same length as one side of a dipole connected to the center conductor of the coax Four radials are connected to the shielded side of the coax at a 90 to 135 degree angle to the vertical element The di pole formula is also used to calculate the length of the radial since radials should be slightly longer than the main element use 240 rather than 234 in your calculations If you are equipped to make the field strength measurements required by Part 15 FCC rules and if you think it would be best to aim or focus your signal in a narrower direction you can con
20. as abso lutely NO rights at all over the rights of licensed broadcast operators and the rights of their listeners to interference free reception If your operation of a device such as the FM30 interferes with ANYBODY S use or enjoyment of an FCC licensed transmission of any kind your only choice is to IMMEDIATELY terminate or change the operation of your low power transmitting device so as to cause no more interference That s it No discussion no exceptions Unlicensed operation of small transmitting devices is discussed in Part 15 of the FCC Rules These Rules are published in 100 Parts covering everything imaginable concerning the topic of Telecommunications The six books con taining the FCC Rules are section 47 of the complete Code of Federal Regula tions which you are likely to find in the Reference section of your Public Li brary If you have questions about the legal operation of your FM30 or any other kit or home built device which emits RF energy it is your responsibility to study the FCC regulations It is best if YOU read and consult with a lawyer if you are in doubt the rules and do not bother the understaffed and busy FCC employees with questions that are clearly answered in the rules FM30 31 Here are the primary dos and don ts picked from the current FCC Rules as of May 1990 This is only a brief look at the rules and should not be con strued to be the absolute complete legal interpretation It is up to you to op
21. ces and that the combined length of your antenna and feedline coaxial cable or other must not exceed 10 feet The technical standards for 88 108 MHz are very different primarily concerned with band width and RF field strength FCC Rules do not differ for stereo or monaural transmissions Broadcasting on the grounds of a school AM emissions only is specifi cally permitted and encouraged between 525 and 1705 KHz under Part 15 221 Use our AM 1 AM radio broadcast kit for this use FCC Rule No 15 239 specifically addresses operation in the 88 108 MHz FM broadcast band for which your FM30 transmitter kit is designed How ever this Rule does not by itself tell you everything you need to know about using a device of this kind Therefore we are noting a series of Part 15 regulations which should be observed a The bandwidth of your transmission is limited to 200 KHz centered on the actual operating frequency Since 200 KHz is enough spectrum space for several different FM stations this is a generous limitation de signed to accommodate cruder FM devices Properly built and adjusted FM30 32 the FM30 kit operates well within this limit In fact its signal should sound no wider than any other FM station when listening on an ordinary FM radio e b FCC Rule 15 215 a says Unless otherwise stated there are no re strictions as to the types of operations permitted under these sections This general provision appears to
22. d sits inside the bezel and the bezel is attached to the base tray using one of the included screws The front panel will only fit on one side of the bezel Look at the two screw holes on the front panel and you ll see two screw holes to line them up with on the bezel Before screwing the parts into the base tray you ll want to peel the protective plastic from the front panel Screw the front panel into place on the base tray F18 Now take the front panel board and slide it into its place on the main board All the pins on J1 should line up with J2 and J4 should line up with J5 F19 Take the connected but not yet soldered boards and slide them into the back of the base tray so that the buttons can protrude through the front panel you just attached There are slots on either side of the base tray for the board to slide into Once you have the main board slid into position as far forward as it will comfortably go see why you trimmed those breakaway tabs in that early step you can position the front panel board so that the buttons protrude nicely and everything is lined up F20 When things are right where you want them take your soldering iron and tack one of the end pins on the connector that joins the two PC boards either J1 or J4 Check placement again and then tack solder a pin on the other connector FM30 24 0 F21 Pull the connected boards out of the case and finish soldering the J4 J5 J1 J2 connections being careful to
23. e holes for it on the backside of the board and be sure the part is flush to the PC board before soldering all three leads on the front of the board It s a little unconventional but much more user friendly this way And while we re on this step adjust the pot right now to halfway up turning it clockwise This is the first step in the setup section and while can probably trust you to read and follow the directions there FM30 22 a O O some of our kit builders are jumping ahead powering up the kit and pan icking because there s no display You must adjust this pot in order to see anything so let s avoid future shock by adjusting it now F3 Install C6 0 10 ceramic disc capacitor marked 104 F4 Install R7 10k ohms brown black orange F5 Install R4 also a 10k resistor brown black orange F6 Install R3 yet another 10k ohm resistor brown black orange F7 Now we ll install S3 one of the momentary buttons You ll see that the part has a flat side and the silkscreen shows you where to place that flat side on the board F8 In the same way install S2 F9 Install the last momentary switch S4 F10 Install R6 270 ohms red violet brown F11 Next we ll install 2 and J5 the two 8 pin dual row connectors These will be used to attach the front panel PC board to the main board They are placed from the back side of the board similar to how you placed R1 This is the
24. e in previous history On the other hand today s FCC en forcement actions get bigger fines and real prison terms for scofflaws From CB now 3 bands of it for varying applications to easy entry level Amateur Radio with long term licensing to numerous unlicensed Part 15 operations the FCC is beginning to look out for the interest and good plans and intentions of private citizens and school community groups as never before in radio com munications history Learn the rules observe them and have fun in radio If you enjoyed this Ramsey kit there are plenty more to choose from in our catalog write or call today CONCLUSION We sincerely hope that you will enjoy the use of this Ramsey product As al ways we have tried to compose our manual in the easiest most user friendly format that is possible As our customers we value your opinions comments and additions that you would like to see in future publications Please submit comments or ideas to Ramsey Electronics Inc Attn Hobby Kit Department 590 Fishers Station Drive Victor NY 14564 or email us at techsupport ramseymail com And once again thanks from the folks at Ramsey FM30 37 This page intentionally left blank for notes and scribbles FM30 38 The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your kit Most problems can be solved without contacting the factory Notice that this is not a fine print warranty We want y
25. er ate within the proper FCC rules and Ramsey Electronics Inc cannot be held responsible for any violation thereof 1 In the past no two way communications use of the 88 108 MHz FM broadcast band was permitted This prohibition does not appear in the current edition of Part 15 Previous editions of Part 15 discussed wireless microphones such as Ramsey FM 1 FM 4 etc while the June 23 1989 revision eliminates this discussion in favor of more detail regarding computer and TV peripherals and other modern electronic con veniences However it is not immediately clear that the 1989 revision of the FCC Rules Part 15 necessarily cancels previous regulations Laws and rules tend to remain in force unless they are specifically repealed Also FCC Rule 15 37 discusses Transitional Provisions for Compliance with the Rules and states in item c There are no restrictions on the operation or marketing of equipment complying with the regulations in ef fect prior to June 23 1989 It is the sole responsibility of the builder user of any FM broadcast band device to research and fully avoid any and all interference to licensed FM broadcast transmission and reception This instruction manual gives you practical advice on how to do a good job of finding a clear frequency if one is available For some frequency bands the FCC sets 100 milliwatts 0 1 watt as the maximum permitted power output for unlicensed home built transmitting devi
26. f test equipment such as our sensitive 50 to adjust it but that is not strictly necessary The best thing to do is to set up your unit and antenna as you intend to use it normally Then using a portable radio go to the furthest distance you intend to receive the transmission from the FM30 front living room garage deck and have someone else turn up the power until you receive the signal clearly Stop adjustment right at this point this is as far as you will need to go You may be surprised by how little power you really need If you have to run it at full power you may need to play with the antenna a bit because that may indicate that you don t have a good match The last setup screen allows you to save all of your changes Pressing the UP button will save them to the internal FLASH memory DOWN will con tinue to use the current settings but will not save them to FLASH in case you need to make some more changes Cycling through all of the displays again will get you back to this screen to save all of your changes The red tunable capacitor C56 is there if you wish to adjust the frequency of your FM30 It is really only for experienced folks with test equipment The units power up very close to right on and no adjustment is needed however for those of you who like perfection and have a frequency counter with good resolution or other test equipment to tell you exactly what frequency you re transmitting feel free to adjust the f
27. ge your operation IMMEDIATELY 6 If you are contacted by the FCC regarding use of this device cooperate fully and promptly 7 Do your own homework and research to understand and comply with pre sent and future FCC rulings concerning devices of this kind 8 Donotuse made up station call signs to identify your transmissions Only the FCC has the authority to issue such call signs Use some other way to identify your transmitting activity such as This is Stereo 90 5 Seabreeze School Student Music Radio and so forth 35 9 Identify the location and purpose of your transmissions from time to time This is common courtesy toward other persons who may hear your signal The FCC is toughest about clandestine transmission which cost time and money to track down 10 Do not assume that the mere fact that you purchased this kit gives you any specific right to use it for any purpose beyond generating a low level RF signal which is barely detectable beyond the perimeter of your per sonal dwelling space Finally the FCC Rules call for the posting of printed notices on devices in tended for non licensed operation under Part 15 Rules You will find such no tices written up for the front or back of the instruction manual for nearly any computer or video accessory that you have seen in recent months Consult the Part 15 Rules for the exact wording of such notices Following is a text for such a notice which responds to FCC rule
28. he board It needs the metal case to bounce off It s best to have it in the case anyway So that you know that there are no stray leads or other objects shorting out traces on the back of the board when testing and when operating the kit Connect the included power supply Also connect your whip antenna You shouldn t operate the FM30 without some kind of antenna a transmitter should always transmit into a load of some kind and not into an open even if it is operating at a relatively low power output Turn the kit on You should hear a beep and see FM 30 Rev 1 2 on the dis play then in a few seconds the screen will change to a default display The default display shows the current set power frequency clipping detector status and the VCO voltage while still attempting to lock Readjust your con trast now if you need to Pressing the SETUP button once brings us to the frequency display Here using the UP DOWN buttons we can select our frequency of operation Note the voltage display which indicates the current VCO voltage This helps us diagnose any problems if something goes wrong If the voltage stays low lt 0 5V or high 29 9V no matter what frequency we choose then the FM30 may not be locked Set your desired test frequency now You should choose an open or dead spot on the FM dial as a starting point if you re not yet sure what frequency you can transmit on without interfering with anyone Check the FCC info
29. he voltage the less the capacitance This is due to depletion layers of the diode junction but we wont get into details here This variable capacitor in conjunction with the stub which is actually an inductor coil is the basis of our voltage controlled oscillator As the voltage increases across D5 the frequency of oscillation increases The stub is just acting like a coil in this circuit and because it is part of the circuit board layout it has a very predictable value This prevents us from having to tune anything in this section like our old products Just turn the unit on and you are good to go The best part of the stub is it s low sensitivity to microphonics Microphonics is a term used for mechanical vibrations that are picked up in a VCO circuit by vibrating components changing in value because of mechanical shock The sub value is very hard to alter from mechanical shock and therefore quite immune to vibration So what actually tunes the VCO you may ask Good question A PLL uses a phase comparator to compare the crystal frequency with the oscillator frequency combined with some internal dividers which are programmable If the frequency is too low U3 s PLL tells pin 7 to turn up the voltage This signal on pin 7 needs to be filtered and amplified for good control and that is provided by Q2 and Q3 along with R18 R17 C34 R20 C38 R21 and C33 All of these parts together act like a low pass filter to slow the tuning time FM30
30. itter such as the FM30 The main point is that you may not cause any interference whatsoever to li censed broadcast services and that you must be willing to put up with any in terference that you may experience In addition to operations not requiring authorization you also have the option of writing a clear and polite letter to the FCC Engineer in Charge of your local district describing your intended operation Mention the operating frequency and planned hours of operation This could be a good step to take if your pro ject is in behalf of a school Scout or community group If you become further fascinated with the service rendered by low power broadcasting other FCC regulations explain how to apply for a license or other authorization which may permit you to upgrade your FM30 or other equipment to accomplish any objective which the FCC sees to be in the public interest and not interfering with other authorized uses of the radio spectrum Lawful use suggestions 1 Build and adjust this kit strictly according to the published instructions 2 Usethe whip antenna supplied with the Ramsey case set CFM 3 Do not modify your kit in any way 4 Check your intended operating frequency very carefully as clearly ex plained in this instruction manual to ensure you will not cause interfer ence to reception of licensed broadcasting 5 If you receive ANY complaint about your transmissions interfering with broadcast reception stop or chan
31. kage marked LM78L05 VR2 LMC6482AIN Dual rail to rail opamp U4 LMC6484AIN Quad rail to rail opamp U5 28 pin microcontroller IC with sticker U1 MCP42010 I P A dual 10k digital pot U2 MPC4921 E SN 12 bit DAC U6 7 naaal N Ah A ESISTORS 4 7 ohm resistor yellow violet gold R35 100 ohm resistors brown black brown R43 44 120 ohm 1 2 watt resistor brown red brown R34 180 ohm resistor brown grey brown R20 270 ohm resistor red violet brown R9 1k ohm resistors brown black red R29 31 36 37 39 2 2k ohm resistors red red red R22 24 adgaaaaocau e FM30 10 uaaaaaaau 5 N 3 3k ohm resistor orange orange red R16 21 27 32 4 7k ohm resistors yellow violet red R5 10 17 45 46 10k ohm resistors brown black orange R2 8 11 33 20k ohm resistor red black orange R18 22k ohm resistor red red orange R38 27k ohm resistors red violet orange R14 28 47k ohm resistors yellow violet orange R23 25 56k ohm resistors green blue orange R15 19 26 30 CAPACITORS O 6 O 7 1nF or 0 0010 ceramic disc capacitors marked 102 C5 33 46 68 69 10nF or 0 01uF ceramic disc capacitors marked 103 C3 7 8 32 49 53 55 dgaaaaaogaaaaoaadud NN BPD OAD A A Aa O 1 1 M 0 O 1 O 1 O 6 O 2 O 1 O 2 O 1 O 1 O 1 0 0 0 0 10 0 10 ceramic disc capacitors marked
32. leave you free to use your FM stereo transmitter in a manner similar to operations of an FM broadcasting sta tion or to use it for any other non interfering practical application e C FCC Rule 15 5 General conditions of operation b Operation is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station by another intentional or unintentional radiator by industrial scientific and medical equipment or by an incidental radia tor c The operator of a radio frequency device shall be required to cease operating the device upon notification by a Commission representa tive that the device is causing harmful interference e d The most specific FCC regulation of 88 108 MHz FM Broadcast band unlicensed operation is that the field strength of the signal must not ex ceed 250 microvolts meter at a distance of 3 meters from the transmitter FCC rule 15 239 If you have any concern about this emission limit have your device checked by a technician with accurate measuring equip ment Remember that the field strength of a signal is determined as much by the antenna as by the RF output of the transmitter itself APPENDIX B UNDERSTANDING LEGAL FIELD STRENGTH The new FCC Part 15 Rules specify a maximum Field Strength of your transmitted signal Since it is unlikely that you have the equipment to carry out accurate field stre
33. making intentions NOTICE The radio frequency intentional radiator device which may be constructed from kit parts supplied by us is intended and designed by Ramsey Electron ics Inc to conform to applicable provisions of Part 15 of FCC Rules The indi vidual kit builder and all users of this device assume responsibility for lawful uses conforming to FCC Part 15 Rules Operation is subject to the following two conditions 1 This device may not cause harmful interference and 2 This device must accept any interference received including interference that may cause undesired operation FM30 36 Final comment A well informed person will see today s FCC Rules to be evolving and pro gressively less restrictive Even though today s technology is far more com plex than what was possible at the time of the Communications Act of 1934 the FCC rules are becoming more relaxed giving radio experimenters more and more opportunities to explore many frequency bands using many com munications modes with no need for a formal license of any kind A thorough study of Part 15 of the FCC Rules which is completely beyond the purpose of this kit manual will show you many legal uses of radio transmitting devices which do not require licensing either amateur or commercial To provide more personal and club radio learning opportunities and to cut down on administrative costs today s FCC permits far more non licensed ac tivity than at any tim
34. minimum gets even stronger as you move from the edge of these circular boundaries toward the antenna This exercise in meters and microvolts demonstrates that the FCC clearly intends to limit the theoretical range of non licensed devices operating in this band It also shows the potential for causing interference at a home down the street from you But it also shows that you can legally put out quite a good signal over wider areas than you might have imagined For other kinds of radio services the FCC restricts such factors as transmitter power or antenna height which cannot really limit the possible range of a transmission under good conditions By restricting the maximum field strength at a specific distance from your antenna the FCC clearly plans for your signal to die out at a specific distance from your antenna no matter what kind of transmitter power or extra gain antenna you are using On the other hand the FCC standards do make it legal and possible for you to broadcast on a school campus campground or local neighborhood as long as you do not cause in terference to broadcast reception Why talk about acres There are three reasons to translate our look at field strength into acres 1 The first one is easy the numbers would get too cumbersome if we dis cussed your possible signal coverage in terms of square feet or square meters 2 It s very easy to see that your signal can easily and legally serve a school cam
35. ngth measurements in microvolts it is useful to understand at least the theory of field strength so that you can understand both what you can expect from such transmitters and what limits the FCC intends Previous limits on non licensed FM broadcast band devices were defined as a maximum field strength of 40uV per meter measured at a distance of 15 me ters The June 1989 revised rule specifies a maximum of 250 uV per meter but measured at 3 meters from your antenna Both limitations are the same in practice 2500 per meter means that an accurate field strength meter with a 1 meter antenna may indicate a maximum signal field strength of 2500 In contrast non licensed operation from 26 96 to 27 28 MHz is limited to a field strength of 10 000 uV per meter at 3 meters In all cases the field strength of a signal decreases in direct proportion to the distance away from the antenna Power decreases by the square of distance for every doubling in distance the signal power is quartered but the field strength voltage is only halved Using this theory we can construct a simple 33 chart to show the maximum permitted performance of a non licensed FM band transmitter The theoretical figures assume a simple 1 meter receiving an tenna in all cases and do not take into consideration that reception can be greatly enhanced with larger multi element antennas and preamplifiers In the following chart the field strength theoretical
36. ns that you re on the edge of clipping If you see the lowercase c it means that you re distorting a bit so if you want to avoid that completely make sure you set the level so that you only see the g Of course you can simply adjust the volume until it sounds right to you The order of characters is approximately on average lt 60kHz g gt 60kHz and lt 75kHz c gt 75kHz and lt 90kHz C gt 90kHz Remember from the circuit description that the indicator doesn t specify the exact level but the frequency with which the audio signal surpasses approxi mately 60kHz of deviation The indicator is based on music signals not test tones Again pressing the setup button will get us to the balance setting The balance simply attenuates one side or the other depending on the adjustment Set in the center there is no attenuation Use the UP DOWN buttons to swing the balance to the left or the right The best way to adjust this is to listen on a re ceiver with headphones and then adjust the balance until lead vocals sound like they are in the center of your eyeballs FM30 27 The last setup display is the power setting This is a relative display simply showing you the drive through the level adjustment pin diode However the power adjustment is not incremental like the display For example 1 2 of the bar is not necessarily 7 of the power If you want exact power settings you ll need to use a piece o
37. o station e College dorm favorite music broadcast service e Drive ins haunted hayrides amusement parks etc e Short range two channel experiments and demonstrations We think you will be very pleased with the transmitting range low noise audio quality frequency stability and stereo channel separation of this build it yourself synthesized FM stereo transmitter If you follow our assembly directions carefully and use your FM30 in accordance with applicable FCC rules a whole new world of sharing music news and views with friends and neighbors awaits you Since the sharing of music and information is vital to the culture of our 21st century global community we realized that our FM30 low power Synthesized FM Stereo Transmitter Kit was certain to attract worldwide interest among hobbyists students and pioneers While the use of the FM30 may need to be limited to wireless stereo extensions in some USA households to comply with FCC Rules Part 15 we have seen it serve very well as a serious though simple broadcast station for remote villages throughout the world where low cost AM FM receivers are available to people of all economic levels After you re done building your kit sitting back and listening to your handiwork consider this many other small transmitters like the FM30 are faithfully relaying news and information to listeners in remote areas around the world The FM30 is most definitely not a toy FM30 4 FM30 CIRCUI
38. of telling us that you blew it we re all human and in most cases replacement parts are very reasonably priced 2 MISSING PARTS Before assuming a part value is incorrect check the parts listing carefully to see if it is a critical value such as a specific coil or IC or whether a RANGE of values is suitable such as 100 to 500 uF Often times common sense will solve a mysterious missing part problem If you re missing five 10K ohm resistors and received five extra 1K resistors you can pretty much be assured that the 1K ohm resistors are actually the missing 10 K parts Hum m m guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey please write or call us with information on the part you need and proof of kit purchase 3 FACTORY REPAIR OF ASSEMBLED KITS To qualify for Ramsey Electronics factory repair kits MUST 1 NOT be assembled with acid core solder or flux 2 NOT be modified in any manner 3 BE returned in fully assembled form not partially assembled 4 BE accompanied by the proper repair fee No repair will be undertaken until we have received the MINIMUM repair fee 1 2 hour labor of 25 00 or authorization to charge it to your credit card account 5 INCLUDE a description of the problem and legible return address
39. ou to understand your rights and ours too All Ramsey kits will work if assembled properly The very fact that your kit includes this new manual is your assurance that a team of knowledgeable people have field tested several copies of this kit straight from the Ramsey Inventory If you need help please read through your manual carefully all information required to properly build and test your kit is contained within the pages However customer satisfaction is our goal so in the event that you do have a problem take note of the following 1 DEFECTIVE PARTS It s always easy to blame a part for a problem in your kit Before you conclude that a part may be bad thoroughly check your work Today s semiconductors and passive components have reached incredibly high reliability levels and its sad to say that our human construction skills have not But on rare occasions a sour component can slip through All our kit parts carry the Ramsey Electronics Warranty that they are free from defects for a full ninety 90 days from the date of purchase Defective parts will be replaced promptly at our expense If you suspect any part to be defective please mail it to our factory for testing and replacement Please send only the defective part s not the entire kit The part s MUST be returned to us in suitable condition for testing Please be aware that testing can usually determine if the part was truly defective or damaged by assembly or usage Don t be afraid
40. our sidecutters and nip off the excess board material then take some sandpaper or bor row your wife s emery board to sand down what s left But don t tell your wife that we told you to borrow the emery board 4 Install U5 the LMC6484AIN quad rail to rail opamp We re starting with the ICs so that you can use the PC board to keep the part flat until you solder it Follow the dot or notch on the chip and match it to the silk screen marking or Parts Layout Diagram for proper placement Make sure that all the pins are through the board and none are bent under or sticking out then slightly bend two corner pins to keep the IC from falling out when you flip the board over Check to be sure that the part is flat to the PC board then solder all 14 pins 5 Install U2 an MCP42010 I P dual 10K digital pot Follow the notched end for correct placement and make sure you solder all the pins 6 Install U4 the LM6482 dual rail to rail opamp following the same pro cedure as the last two ICs T Install U6 MPC4921 E SN 12 bit DAC Be sure the notched end matches the silkscreen and the part is flat on the circuit board before sol dering all the pins 8 In the same way install U7 another MPC4921 E SN 12 bit DAC Again check your orientation before soldering 9 Install the socket for U1 the 28 pin microcontroller IC Install the socket the same way you installed the ICs in the above steps making sure the part is flush to the PC board before
41. pus or wilderness campground 3 And if we remember that typical urban single family home sites run from 1 4 to 1 2 acre on the average it should become extremely clear that your obligation to avoid interfering with broadcast reception can easily involve hundreds of homes before adding apartments In fact the most significant distance in the above chart is the 1 9 LV signal strength permissible at 1260 feet about 1 4 mile covering a circular area of about 114 acres A quick glance at stereo FM receiver specifications shows typical sensitivity of 1 7 uV before considering high gain antennas or preampli fiers Your non licensed signal can provide serious competition to a public broadcast station fifty miles away a station which someone in your neighbor hood may have set up a special antenna to enjoy Calibrated field strength meters such as described in the ARRL Radio Ama FM30 34 teur s Handbook can detect signals down to about 100 microvolts To meas ure RF field strength below such a level professional or laboratory equipment and sensitive receivers are required A sensitive receiver responds to a sig nal of 1 or even 5 microvolts delivered to the receiver input by antenna If the antenna is not good the receiver cannot respond to the presence of frac tions of a microvolt of RF energy SUMMARY The present edition of Part 15 of the FCC rules does not provide detailed guidance on ALL aspects of using a low power transm
42. quency It also sends the proper signals to the level control IC U7 which is just a digital to analog converter U4 the digital pot and 051 the LCD display In all there is a lot going on inside of the microcontroller and be glad you don t have to do things with a bunch of dip switches any more Now here comes the fun part the stereo modulator IC U3 This IC is a great little part and contains a lot of circuitry that helps us get on the air with minimal fuss and great sound This IC not only contains a stereo multiplexer but also a phase locked loop PLL audio filters and equalizations The audio filter portion of the part adds a little more low pass filtering to the audio to increase quality more than what our external low pass filter does on its own The equalization portion enhances the high frequencies for the radio standard of 75uS in the US 75uS is just a term used for a high pass filter to enhance the high frequency audio before transmission to help reduce noise upon reception The PLL is the portion of the IC which locks your chosen transmission frequency to the crystal reference X1 The PLL portion also contains an oscillator circuit which works in conjunction with the external parts of D5 and the STUB that weird trace on the back of the board D5 is called a varactor diode and is a special variety of diode that is connected backwards As a reverse DC voltage is applied across the diode its capacitance varies The higher t
43. requency with this cap The swing is ap proximately 4kHz total If you don t have access to test equipment please don t adjust this cap and trust us when we say that you don t need to USING THE FM30 WITHIN THE HOME Typical use for the FM30 would be to connect it to a personal computer within a large home so that whatever MP3 or other audio files are playing can also be tuned in on portable FM radios in other rooms the garage or out in the yard The provided whip antenna should cover a typical home s boundaries quite well An external antenna can be used for a larger coverage area if de sired Use the RF adjustment control to fine tune the RF output level to just reach the area you intend to cover The audio connection consists of using shielded audio cables to connect the line or speaker level output to the audio inputs of the FM30 Consult the litera ture that came with your stereo equipment Even if you intend use of the FM30 for your own home and family it is still your responsibility in accordance with Part 15 of the FCC Rules to ensure that this operation does not cause interference to your neighbors FM30 28 EXPERIMENTAL BROADCASTING PROJECTS To use the FM30 successfully as a broadcasting service for interested listen ers in a school or immediate neighborhood most of your effort will be concen trated on smoothly managing or mixing the audio signals fed into the trans mitter input Operation of the transmitter i
44. ritten directions for all parts when there s a right way and a wrong way to sol der it in Diode bands electrolytic capacitor polarity transistor shapes dotted or notched ends of IC s and so forth 4 Solder all connections unless directed otherwise Use enough heat and solder flow for clean shiny completed connections FM30 12 FM30 PARTS LAYOUT DIAGRAM o00 oo Jaz ZE m E ales oe J FM30 13 FM30 PC BOARD ASSEMBLY STEPS The FM30 is one of our larger more complicated kits however if you follow the steps closely you will find that it will go together smoothly We will start with the larger main PC board We ll have a working kit in no time 0 1 Notice that your board has all the surface mount parts preinstalled and it also has a small piece of foam on what will be the front panel board and a piece of copper tape on the main board These parts were installed on purpose Please don t peel them off You ll see why they re there when we get further along with construction 2 The first thing you ll have to do is to separate the front panel PC board from the main PC board Simply grasp the two boards and carefully snap them apart 3 Once you have the boards apart you ll notice that there are little tabs left where the boards used to be connected You ll want to trim these down so that the board fits into the case correctly Take y
45. rma FM30 26 tion section of this manual for more details on legal part 15 broadcasting Use the UP DOWN buttons to select your frequency Pressing the SETUP again gets us to the mode display Here you can toggle Stereo and Mono modes Another press of the SETUP button brings us to the volume display Connect your line level source to the FM30 Your source can be a CD player line out a computer sound card line output or any other audio source you desire as long as itis line level Anything other than line level audio will sound distorted and cost you time troubleshooting a non existent problem NEVER connect the FM30 audio inputs to speaker outputs of a high power stereo system such a connection will destroy the IC chip Trust us when we say that a true line level audio source will give you the best results with your FM30 The default volume setting is roughly 72 of full which is a gain of 1 The means that 500mV peak audio coming into the FM30 is 10096 modulation typically depending on frequency The volume display also includes the clipping detec tor status and you should adjust the volume until the indicator toggles from to g occasionally roughly a 50 50 timing between the two with an occasional c mixed in If the character is always at the modulation is too low and if C ever shows up capitol it means you are overmodulating It s best to set your level up or down until you see the lower case c which mea
46. se We re going to bend that tab just to be sure it doesn t short to J2 Simply bend it gently away from J2 so that when you solder the LCD board to the front panel board no part of that tab is touching any of the pins of J2 Be careful when bending it because it s holding the LCD on and you don t want to damage anything F15 Now you re ready to solder the LCD board to the front panel board Hold the LCD board flat on the IC on the back and solder one of the cor ner pins then check flatness before soldering the opposite corner pin Carefully solder the rest of the pins of the connector Be careful handling the board when you re done those pins stay hot for a little while F16 Look over your connected boards and make sure all the solder joints look good all parts are installed the LCD is nice and flat and flush to the board using the IC as a guide for flatness Our next task is to connect the main and front panel PC boards and once it s done you won t want to try and get them apart again so check the boards over carefully now before it s too late The flatness of the LCD board is especially important for the kit to fit correctly into the case F17 We ll make sure our boards are going to line up with the front panel and case before we solder everything together and it s too late Take the front panel board one of the bezels plastic case parts that frame the metal front panel and the bottom base tray for your case The front panel boar
47. side you ve been soldering to that has no silkscreen on it The shorter pins go through from the back of the board and are soldered on the front leaving the longer pins to be connected to the main PC board in a later step Be sure these parts are seated nice and flat before soldering F12 The next part we ll install is the 2x8 line LCD display DS1 First you ll need to snap off the two metal tabs on the front of the part to make it ready to install Be sure you grab the correct tabs the ones on the bottom hold the display in place so you don t want to remove those Grip one of the front tabs with your needlenose pliers and bend it back and forth until it comes off Do the same for the other tab C BREAK OFF THESE TABS F13 Next take the 14 pin dual row connector and place the short side pins through the LCD display board from the back The back is the side with the big IC on it and the front is the LCD side Solder all 14 pins F14 Once the pins have cooled place the LCD board through the holes for the connector on the front panel If you push the LCD board flat you ll see that the IC on the back of it is a good marker for height and flatness Otherwise there s a piece of foam tape on your board as a spacer You ll also see that J2 sits underneath the LCD board With the board pushed FM30 23 flat against the IC take a look at the tab on the LCD that s closest to J2 Yes it might be a little too clo
48. solder them all and not to bridge any These are both the physical and electrical connections from the main to the front panel PC boards so make sure you have solid reliable solder joints F22 Before sliding the board back into the case bottom take note of the piece of copper tape on one edge of the PC board it should be taped to the silver part of the board where it will slide into the case bottom This tape will give you a better path to ground and will give the board a snug fit in the case Do not remove it F23 With the boards soldered together and the main board in the correct position place D4 the small green LED into the front panel but do not solder it The part has a flat side and so does the silkscreen for the part but it s a little hard to see so you can also check placement by the longer lead This longer lead is the positive side and should be placed in the hole opposite the flat side on the drawing the side closest to R6 Next slide the circuit board assembly forward in the case bottom until you can t push it forward any further with the buttons properly protruding through the front panel Now align the unsoldered D4 so that its green lens fits into the hole in the front panel It is finally time to solder this little bugger in place When you re done nip off the excess lead length on the back of the board just as you did with all the other parts That s about it Give the board one last good checkout before we apply power
49. soldering and placing the FM30 14 notched end as shown on the Parts Layout Diagram and PC board silk screen O 10 You can now place the microcontroller U1 in the socket you just in stalled It s the IC with a sticker on it to show the revision number of the software Be sure the notched end is placed correctly and press the chip into the socket then check for bent under or bent out pins Next we ll start installing the rest of the components starting at the corner of the board near J3 Place the board so that you can read the writing on it right side up O 11 Install C8 10nF or 0 01uF ceramic disc capacitor marked 103 Disc caps have no polarity and can be installed in either direction We ll always let you know when you have to be particular about how to install a compo nent O 12 Install C5 1nF or 0 001uF ceramic disc capacitor marked 102 O 13 Install D1 a 1N4000 series diode 1N4002 1N4008 Note the stripe or band on one end of the part and the stripe marked on the PC board silkscreen and Parts Layout Diagram This diode must be placed correctly to function properly Line the part up with the mark on the board and sol der it in place 14 Install L1 2 2uH inductor green body red red gold silver 15 Install C7 10nF or 0 01uF ceramic disc capacitor marked 103 16 Install C50 100pF ceramic disc capacitor marked 101 17 Install L3 2 2uH inductor green body red red gold silver 18 Install R45
50. sult an antenna handbook and design a suit able gain antenna See Appendix A concerning FCC field strength limitations An FM VHF TV receiving antenna could be modified for such a purpose Ham radio books and magazines are filled with antenna principles and ideas which can be adapted to your application Our TM100 Tru match FM antenna is an ideal mate to your transmitter It features proper impedance matching for optimum power transfer and range See our catalog for details ANTENNA ALTERNATIVES If your situation involves a single large building or multi level home where re ception from the FM30 antenna may tend to be uneven because of walls and other VHF path obstacles you might set up the FM30 s output in a carrier current configuration If you know how then do so safely If not you can show your FM30 and this book to a licensed radio engineer and negotiate with that person for a safe installation which will feed your signal through interior wiring of your home or building Do not attempt such an installation unless you know exactly what to do and not to do Also because such an installation is beyond the original purpose of this kit and the safety standards intended for all Ramsey kits and because we have not tested the FM30 in such an installa tion we cannot provide further details FM30 30 APPENDIX A FCC RULES AND INFORMATION The Rules of the FCC Federal Communications Commission and your kit built FM Stereo Transmit
51. tatic electricity or low frequency interference Whew a lot to absorb here Surprising how much great info can be gleaned FM30e 8 from a kit isn t it We covered a lot of aspects of electronics here in one simple project digital power RF and analog If you want more information on these subjects there are a lot of great electronics books and websites out there and here are some keywords to search for COMPARATOR VARACTOR DIODE PIN DIODE LOW PASS FILTER DIGITAL POT DAC Digital to Analog Converter JFET Q4 MULTIPLEX Have fun and happy learning Now on to the kit building Ramsey Staff FM30e 9 FM30 PARTS LIST FRONT PANEL SEMICONDUCTORS O 1 Small green LED D4 RESISTORS O 1 10k ohm trim pot for display contrast Orange top marked 103 R1 O 1 270 ohm resistor red violet brown R6 O 3 10k ohm resistors brown black orange R3 4 7 CAPACITORS O 1 10nF or 0 01uF ceramic disc capacitor marked 103 C4 O 1 0 10 ceramic disc capacitor marked 104 C6 MISCELLANEOUS O 3 Momentary buttons S2 3 4 O 1 2x8 line LCD display DS1 O 1 14 pin dual row connector for DS1 O 2 8 pin dual row connectors J2 5 MAIN BOARD SEMICONDUCTORS O 1 1N4000 series power diode any number from1N4002 to 1N4008 Black body grey stripe marked 1N4002 D1 1N4148 Small signal switching diodes Marked 4148 D3 2N3904 NPN transistors marked 3904 Q2 3 78L05 5V regulator in a TO 92 pac
52. ter An interim explanation of applicable FCC regulations supplied as a personal assistance to FM30 builders by Dan F Onley KAZRA It is the policy of Ramsey Electronics Inc that knowing and observing the lawful use of all kits is a first responsibility of our kit user builders We do not endorse any unlawful use of any of our kits and we try to give you as much common sense help about normal and lawful use as we can Further it is the policy of Ramsey Electronics Inc to cooperate with all applicable federal regulations in the design and marketing of our electronics kit products Finally we urge all of our overseas customers to observe the regulations of their own national telecommunications authorities In all instances compliance with FCC rules in the operation of what the FCC terms an intentional radiator is always the responsibility of the user of such an intentional radiator To order your copy of FCC rules part 15 call the US Government Superinten dent of Documents at 202 512 1800 or fax at 202 512 2250 To order the correct document ask for CFR Title 17 Parts 1 to 199 The cost is 24 00 Master Card and Visa are accepted In the United States this is how the FCC regards your transmitter kit Licensed FM broadcast stations and their listeners have ALL the rights Your use of a device such as the FM30 kit MAY have some limited privileges in lo cally unused band space but your non licensed use of the FM30 h
53. tself consists simply of the following Correct construction and adjustment 2 Carefully checking for an open frequency between 88 108 MHz in accor dance with FCC Rules Part 15 3 Setting up a suitable antenna 4 Connecting the audio source to the input jacks 5 Turning on the transmitter while you intend to be on the air and turning it off when you are finished The more home built your complete setup the more it is in conformity with the spirit of FCC Part 15 regulations You can greatly add to the versatility and professionalism of your transmitting station by adding an audio mixer and or processor Mixers allow you to smoothly blend from one audio source to another just like the commercial stations do Our STC1 Stereo Transmitter Companion provides audio proc essing in one easy package The STC1 allows you to sweeten the audio for more impact and punch Plus it has brick wall low pass filtering on the stereo inputs to prevent that bothersome swishing and squealing sound that is often found when using lower quality CD players as the audio source Check out our free catalog for all the details ANTENNA IDEAS A simple yet very effective antenna for the FM30 consists of a dipole set up either horizontally or vertically and connected to the transmitter output jack through a few feet of coaxial cable either RG 58 RG 59 or miniature RG 174 available at Radio Shack and other sources Correct dipole lengths for m
54. ucing mixing products of various frequencies Ok perhaps that is too much to bite off In layman s terms this low pass filter prevents high frequency audio signals like cymbals and chimes from getting garbled up during the creation of a stereo signal before transmission so it increases the audio quality of the final transmitted signal This signal is then piped off to U3 the BH1415F stereo modulator IC We wont get into that quite yet because we have another circuit of importance before this that you will find to be very helpful to you during day to day use Take a look at D9 D10 and R39 These are peak detectors that sample both the left and right channels and combine them together which is presented on pin 3 of U5 A The levels that these diodes detect are then compared against the constant voltage level seen on pin2 of U5 A Notice used the term compare U5 A is set up to be a comparator since it has no negative feedback Once the voltage on pin 3 surpasses that on pin 2 our reference the state of the output pin 1 of U5 A goes high 5V If the voltage on pin 3 goes below that on pin 2 the output goes low 0V The comparator is set up with these specific diodes and voltage reference so that audio peaks surpassing a very specific level flip the comparator state back and forth This change of state is then sent to the microcontroller U1 and the program in there counts how many times this happens in an interval of time and then computes
55. ve made some good progress so far and your board is starting to have a few parts on it Take a break if you need to and we ll start again in the area right below J8 assuming you re orienting the board so that you can read the silkscreen and it isn t upside down l Il go warm up my forgotten coffee and be right back Ok break s over Let s keep going 0 46 4T 48 49 50 51 52 53 54 55 56 5T 58 59 60 61 62 lead should be placed in the hole marked with the sign 63 64 65 66 Install L2 2 2uH inductor green body with red red gold silver bands Install C28 100pF ceramic disc capacitor marked 101 Install C29 yet another 10uF electrolytic cap Orientation Install C52 560pF ceramic disc capacitor marked 561 Install R46 4 7k ohm resistor yellow violet red Install R43 100 ohms brown black brown Install R19 56k ohms green blue orange Install C25 100pF ceramic disc capacitor marked 101 Install C23 560pF disc capacitor marked 561 Install R15 the last 56k ohm resistor green blue orange Install R14 27k ohm resistor red violet orange Install R33 10k ohms brown black orange Install R8 10k ohms brown black orange Install R38 22k ohms red red orange Install C36 0 10 ceramic disc capacitor marked 104 Install R16 3 3k ohm resistor orange orange red
56. y steps the 12V down to 5V for our logic and audio circuits At this point our voltages are very well regulated for lowest noise C10 works with VR2 for good regulation Now on to the audio input and control circuitry Audio is introduced into the FM30 at J8 left and 10 right For now we will only talk about the left channel as the right channel is a duplicate of the left Immediately after J8 you will notice L2 and C28 These parts are to prevent EMI produced from transmitting from getting into your FM30 and messing up the audio quality similar to what we talked about in the power supply above After this filter the audio goes into U4 A a simple rail to rail opamp R46 U2 A and R43 set the gain of the opamp You may wonder where the heck is U2 A don t see any pots in my kit Well U2 A is a digitally controlled pot Inside of the IC are a bunch of transistors switching in an out resistor arrays to make a digitally controlled variable resistance In turn this variable resistance controls the gain of U4 A thus U2 A is the volume and balance control We just happened to draw the IC like a pot in the schematic software to make more sense After this gain stage the audio moves on to U5 B another opamp FM30e 5 surrounded by a bunch of resistors and capacitors This arrangement of parts is a low pass filter This filter is designed to help reduce high frequency audio signals from mixing with the stereo pilot signal and prod
Download Pdf Manuals
Related Search