FSM User Guide for V1.1 PCB
Contents
1. How It Works 1111Leee eee Leeeee eee eene nennt 18 Power SUDDIY O ECION ounce id caca 18 LOG AMPIE SCCUO NEE 18 LED Bal Graph sec a rs des 19 Tone Generator SOCOM oopis EE E a T 20 AppendbcA FSM VET SCchemalle E 21 Appendix B1 PCB V1 1 Parts EISE eege ee ENEE 22 Appendix B2 Additional Parts List ino rore ocio cies uere Eege 23 Parts LIST Clm 23 Appendix C1 PCB VII TOD ET EE 24 Appendix C2 PCB V1 1 Bottom Side eerie Leere recreo eurn e ceu ener neun 25 Appendix D PCB V1 1 Copper Pattern not to scale 26 Appendix E Top Panel Drill Ditert 27 Appendix F Input Impedance E 28 Document History Issue Date Chamges 24 June 2007 A a Issue 1 Copyright Dave Adshead 2007 FSM User Guide Page 3 of 28 Field Strength Meter User Guide This section explains how to use your Field Strength Meter If you have not yet built the meter proceed to the Kit Assembly Instructions section If you have any questions or are unsure about what is meant by anything please email support debuginnovations com and we will be pleased to assist you Overview A field strength meter is a general purpose instrument that has many uses including measuring RF signals checking transmitters tuning antennas and measuring antenna radiation patterns This design is based on2. 9V supply decoupled by C6 There are 2 reasons for this e U4 can only supply 100mA A larger regulator could be used but it would need a heatsink e To keep high current swings on the LED supply from disturbing U1 which has a very large dynamic range Internally U2 contains 10 comparators and a voltage divider The outputs of the comparators are connected to the LEDs As the input passes each threshold the next comparator is turned on giving the familiar rising bar pattern Tone Generator Section i TPI C4 LI LSI 47mH PIEZO SOUNDER VCC U PIC12F675 yop GPO ANO CIN WICSEDAT GPI ANI CIN VREF ICSPCLE 4 GPYANYTOCKLINT COUT GPA MCLR VPP GP4 AN3TIG OSCI CLKOUT e Q1 VSS GPS TICKI OSCI CLKIN 4 E MPS44 R6 3K3 TT ege U3 is a general purpose microcontroller programmed to operate as a tone generator a sort of audio frequency VCO The program takes 2 analogue inputs e The signal strength output from U1 e AO to 5V control signal from the volume control potentiometer These signals are processed by the program so as to control a free running software oscillator whose output appears on pin 2 The signal strength determines the oscillator frequency whilst the volume control signal controls the mark space ratio of the output To generate a loud signal on the piezo sounder Q1 and L1 are pumped by the oscillator output L1 resonates with the capacitance of LS1 to produce a large voltage across LS1 approx 50 100V Q1 i
3. finish up flush with the top surface see photo right 90 in order to get a neat finish they must be stood off the board a precise distance and aligned accurately with the front panel slot In order to make this easier some jigs have been made which are available on loan from the club They are normal cases which have had the back removed n this way the LEDs can be fitted and aligned in the slot then soldered from the back of the case The procedure is as nd follows 1 E r Loosely fit LEDs D1 to D10 in their positions on the board Do not solder them at this stage Take care to insert the LEDs the correct way round the anode is the longest lead and should be inserted in the hole marked A nearest the edge of the board You will find that the LEDs are a tight fit especially if you try to push them down to board level Carefully slide the PCB into the special jig case The PCB goes in the last slot the one farthest away from the front panel Push all the LEDs into the slot and turn the case over so the LEDs are resting on the workbench If possible you can use a glass table to check the LEDs are all aligned before going any further Make sure all the LEDs are aligned when pressed together then solder them all You may wish to solder one leg of each LED then check the result before soldering the second leg Once you are happy with the appearance of the LEDs cut the excess lead length off and your board should fit
4. in the real case This is because the green plastic of the LED is not exactly square It slopes from the base where it is nearly 5mm wide to the top surface where it is only 4 9mm wide The spacing between LEDs on the PCB is 4 92mm and the slot in the case is 49 2mm long This forces all the top faces together to give a seamless appearance when finished Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 16 of 28 Step 7 Testing amp Calibration After assembly the unit needs to be tested and calibrated before use as follows 1 With the PCB out of the box and on an insulating surface attach a battery and switch the unit on with VR2 Measure the voltage between TP1 and GND It should be approximately 5V If it is not there is a fault with the power supply on the board first check the battery is good then check D13 is fitted the correct way round If you see a very low voltage on TP1 check for a short between the 5V power and GND Next do some basic checks to get confidence that the unit is basically ok e Push a small wire into the centre pin of J1 Touching the wire should show a signal on the LEDs and make the tone change pitch If it does not check the voltage at TP2 if it changes when the wire is touched then the circuitry around U1 is working correctly and you have a problem with the LED driver U2 and or the tone generator U3 If the voltage on TP2 doesn t change when the wire is touched then you h
5. 2 Component Identification First check you have the correct PCB version V1 1 The version number is shown on the bottom side of the PCB both on the legend and etched in the copper PCB Version ma Y e Number ep 0600000000 e CODO CX 2 5900000000 oO LJ Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page of 28 Open the bags and check you have all the components on both parts lists see Appendix B1 amp B2 Resistors The SMD resistors are all clearly marked with a 3 letter code as follows Designator Value Marking Ro D b2 Variable Resistors You should have a preset and a potentiometer as follows Designator Value Type VR1 100K preset VR2 10K linear potentiometer with switch Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 8 of 28 Capacitors The SMD capacitors have no markings They can be distinguished by their packaging as follows Value Packaging 100pF Cardboard 470nF Clear plastic C2 C7 100nF Strip of 6 IMPORTANT To avoid mis identification do not remove more than one capacitor from its packaging at a time Unpack them one by one as they are soldered down The electrolytic capacitors are clearly marked They may not be identical to the photo and may have different voltage ratings as components from different manufacturers can look slightly different Designator Value C9 8 C10 100uF E e Pi r e e EE Ind
6. 9 3853 RAP 16 0075 RS 447 437 FN 107 6295 RAP 18 0094 FN 873 1209 RS 262 2220 FN 873 1225 RS 262 2062 RS 101 2385 FN 873 1195 RS 262 2214 FN 102 2403 RAP 35 0286 TOTALCOMPONENTS 4 U3 needs to be programmed before assembly The blank part number is given above Parts supplied in the kit are already programmed Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 23 of 28 Appendix B2 Additional Parts List PCB Double sided PCB V1 1 80mmx 56mm j PANEL2 End panel for bottom of box pain See PANELI LABEL Sticky label for box tf Parts List Key Designator A unique identifier for this part on the board e g R1 C1 Q1 etc This can be given as a range or list e g C1 C3 means C1 C2 and C3 Part Type The type or value of the component e g 10K 100nF Al S04 The shape of the area on the PCB for the component Often this translates to the package style e g the same value of resistor comes in several different sizes transistors come in standard cases e g TO 92 and you can often get the same IC in a DIP or a surface mount package Quantity required on the PCB A blank indicates that the component is accounted for somewhere else A quantity of zero indicates that there is a space on the PCB but the component is not fitted in the standard build Part Number Part numbers are for guidance only and all part numbers shown are suitable however part numbers ar
7. ANT Fit the capacitors one by one DO NOT remove C8 from the packaging until C1 has been fitted as there are no markings on the capacitors Fit capacitors C4 to C7 100nF 1206 There are 4 x 100nF capacitors on the bottom side of the board and 2 on the top side so you will have 2 x 100nF left at this stage Fit U3 Programmed PIC12F675 This is the most difficult device to solder on the board Take your time and check your work carefully after soldering Check for shorts with a multi meter and use solder wick to remove excess solder if necessary Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 14 of 28 Step 5 Top Side Assembly Except LEDs OU imm h4 imm 002 HS e Li s p T T T 2 e 6 FAT M 460006006000 a J2 eje Bon END O posite CWW S wn du pE Turn the board so it looks like the diagram above and fit the parts in the following order A fully assembled PCB is shown in Appendix C1 1 Fit capacitors C2 and C3 100nF 1206 2 Fit diodes D11 and D12 1N4148 Ensure they are fitted the correct way round 3 Fit diode D13 1N4001 Ensure it is fitted the correct way round 4 Fit test points TP1 Red TP2 White amp TPG Black TPG is marked GND on the PCB legend 5 Fit Q1 MPSA42 and U4 78L05 Be careful as these devices are very similar 6 Fit VR1 100K Preset 7 Fit U1 AD8307 and U2 LM3914 Ensure they are fitted the cor
8. DUM AM ec eee fy e LA PE e I 9 b ar ME Paaa y A LA AAA LY NE E OS k pas A A AA ILLERA AUR 4 a A Y I ET 7 Le ut ute te FER UK dra 4 B j u x L x RK AM ed T tet TERANA Sal LC Y died e ns e S M Ae Se E m PECET da de xn rbi B pas CA dR AAA AAA 43141 A z 4 wd Pee ee T 4044 3m 4x mto 45 Te ES LEG Wn M4 RAN ISA dd o ar M D Ae A ASAS dd CON CA St A a 4 4 R44 A ag Of sg Ek TUS i 5 Ni san UA mE A UN Nom AAA D LODS CEREREA atd edu dan 4 cen WK doe LATA 4 D4 444345 did AO R74 140417 di SES Geer 444 L4 i 4384 45341 KEES EEKE een 4534 dad TETAS EK VE AA 444 A44 Im onm e inv REEL p A A L k r A x gt eke ee ee Cee ee ee at LAA ARA AA K d FAA a de oe A AS Za AAA A EA 4 44 ar d 4 5 04 s 4 3 i ia E pam Sy La LAA AAA d LAMA TA AAA ANA Aya TARA IIA LA S OP P A AA NARA LAA 4 Pus dde i dad ida dd ET AAA TARA a NUEVE EFI Pads 19d 44 Hd A TIT ETY IA Pit te te LATA d Ze A tt nena vy pP EI AAA EA AMA AAA ka ER POESIA SE NADAL Ly dt E d 4444 4 ALAS d ani wegl das Jn E idad A CN X 9d d TU P M 2 VS iR i P VA Add AA AN AA eee Lo a pa AE AENA PAm i da da al da h ee ee Ev ah ER 4 244 d dd mr d KE OSC WEEN n hd he ATA AAA AA ae 2p TR m af d Oe T vk KEN 4 4 A TEF Y d e AN E Pd laa E HANA Ls AA ia f VJ LER P2 CT vorn d x 1 y Ed L
9. FSM User Guide Page 1 of 28 Field Strength Cambridge amp District Amateur Radio Club User Guide STRENGTH and Kit Assembly Instructions PCB V1 1 Important Always use or print this document in colour as there are references to the colours of components Errors may occur otherwise Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 2 of 28 Contents Slim 2 Bees elt 2 Field Strength Meter User G ide 1 acia calida 3 OVENI O N e AME a MI Eid mu IM E M 3 AO A A Mu ei 4 Operational TS a 4 Replacing the Batle Veere A A 4 FSM V1 1 Kit Assembly InStructiONS cooonnnccccnnncncccconncanconcnnnannconcnnnnnnconennnnnncorennnannrrrenanananns 5 Step 1 Unpacking Your IL eee detects id 5 Step 2 Component Jdentfcaton ccc cecccceecceceseeceeeeeceeeeeceeeeceeesseeessaeeessaeeeseaeeeseesesens 6 SE HOA T Variable IReSISIOIS c xaiisese rodeo nia a o eee T El ee 8 MAUI S ee a ida 8 DIES Maps m 9 Trans iO EE 9 Integrated Circus oi A ia 10 Ather Components ee Ee 11 Step 3 Preparing For PCB Assembly AA 12 Pr Tale OL TWO SIG CS E EE 12 Step Ee elle E le EE 13 Step 5 Top Side Assembly Except LEDS cocccoococcccocnocococnccconconconannnnonannnnnnnnnonnnnanos 14 Sle Os LED ASSemDIV ista dci atadas 15 Step 7 Testing Calibrator EE 16 Slepo Fila s nl ata aos 17 FSM V1 1 Circuit Operation
10. ave a problem with the log amp U1 e Adjust VR2 to check the volume control works correctly The tone should be very loud If you get no tone check U3 R6 and Q1 are fitted correctly If you get a quiet tone check L1 with a multi meter it should have a resistance of about 120R e Adjusting VR1 should change the LED display and alter the pitch of the tone If it does not check VR1 and R2 If you wish to calibrate the unit inject a suitable signal into J1 from an RF signal generator e g a 10MHz sine wave DO NOT exceed 3V pk pk Adjust VR1 to get the LEDs to match the scale OdBm 1mW It is possible to choose a different intercept point and make a new scale but the gain is fixed at 10dB per LED Alternatively simply adjust VR1 until D1 just lights In this configuration D1 behaves as a power LED If you have a suitable signal source apply a signal to J1 and check the LED meter works correctly and all the LEDs can be lit DO NOT exceed 3V pk pk signal amplitude You may also want to check the frequency response the unit should work from 1MHz to 500MHz f your meter doesn t work you may find it useful to read the circuit operation section to help with fault finding Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 17 of 28 Step 8 Final Assembly Finally the unit can be put into its box as follows 1 Drop the top panel over the thread of J1 and the shaft of VR2 Make sure it is the corre
11. ct way round so the screw holes line up with the case Fit the nut and washer on J1 the washer goes on the visible side of the panel directly beneath the nut Do not tighten the nut at this stage Slide the PCB into the case being careful not to damage the LEDs as they feed into the front panel slot The PCB goes in the last slot the one farthest away from the front panel See photos Screw the top panel in place using 4 of the screws supplied You may find it better not to fully tighten the screws until step 4 is complete as the LEDs will be very difficult to move There is a small amount of play where J1 goes through the top panel Use this play to adjust the height of the LEDs to remove any alignment error with the front panel surface and tighten J1 s nut Check that VR2 turns freely in the top panel hole If it does not the simplest thing to do is enlarge the hole slightly as it will be covered by the knob Fit the knob to VR2 Take care to fix it with a suitable clearance from the panel and positioned so that the white line points correctly when operated Push the cap in place Connect a battery not supplied and slide it into the case The battery clip should go in first and end up touching VR2 when in place Peel the protective plastic from the bottom panel and screw it in place using the remaining 4 screws supplied with the unprotected side on the inside of the box Note that the panel is not symmetrical it only fits i
12. dimensions in mm Issue 1 Copyright Dave Adshead 2007 FSM User Guide Page 28 of 28 Appendix F Input Impedance 1E ET ER TEE Pa 54 03 1 As is apparent from the Smith chart the input is not matched to 500 The chart can be used as a guide for designing matched filters etc Some useful frequencies are given below More data is available on request from Dave Adshead Equiv Matching Freq MHz Real Imaginary C L L C R for 50R 143 65 12 01 75 14 14 75pF 83 25nH 38R s 430 75 8 35 11 75 4 34nH 31 45pF 42R s Issue 1 Copyright O Dave Adshead 2007
13. e listed in order of preference usually because of price Part numbers are prefixed by supplier as follows Prefix Supplier 1 Website Farnell Electronics http uk farnell com RS Components http rswww com Maplin Electronics http www maplin co uk Rapid Electronics http www rapidonline com DK Digi Key UK http dkc1 digikey com uk digihome html Issue 1 Copyright O Dave Adshead 2007 Page 24 of 28 FSM User Guide Appendix C1 PCB V1 1 Top Side E E 000 ge NARA E a SON EEN UIT A e mr n Bei GEAR GAN i REVERE ix e tart t E Y KA a Ur LAM SN NUN PER KL n A TIA A t e iia ra N EA o AENA D pe di 4 gt gt d DM e ir p NT ECKER Wess 1 AA A freche Ze CE GREEN KEE SE HES ARI IA Bas we s M ou TeL DA L ARA a TAEE E i de E La du di d du D ai f a z AA n Vi roa ds 4 Wwe TA e i NA d t T H E ki A RIA ed dtu P X VY AST ve eg ta ut EA or ee on ae sl l 3 o D y WIE B ech ve ER F Xe d Aa E S 9 P P a a w l db AW 4 Tis ee LAR AS COM de ie AE KS AA ARS L Ro b KI E 4 Alt A vs Fi 3 44 4x SERRE CA EK dy X eee daa i m C v R WW n 5 da AS A ae ex AA AEN S NA CL UE e L Te E a Re ay T f E tuis He a da das Ares S EU E REA Vi EK EN REPE ERE VE gt lt DR E a je T A nV a A RY RELY AN b i ge i a da hh dedi am os ui iuh im US MAT RASS SAA
14. ep instructions to assemble and test the kit It should be possible to complete the assembly in 2 3 hours It is not a difficult kit to build but there are some surface mount components which need careful soldering Therefore this kit is not recommended for novice constructors If you have any questions or are unsure about what is meant by anything please email support debuginnovations com and we will be pleased to assist you Step 1 Unpacking Your Kit Your kit should come in a sealed package as shown below These instructions are for PCB V1 1 Please check that your kit label says PCB V1 1 Field Strength Meter Kit A Cambridge amp District Amateur Radio Club Project Designed by Dave Adshead June 2007 PCB V1 1 S N 0001 Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 6 of 28 Field Strength Meter User Guide and Kit Assembly Instructions PCB V1 1 nt Always use or print thes document in colour as There are references to the colours of components Errors may occur otherwise Once opened you should have the following items Ensure you have all the items before proceeding 1 These instructions 2 The PCB 3 Abag containing the small components mainly SMD 4 A bag containing most of the through hole components 5 A bag containing an LM3914 chip 6 A bag containing the mechanical parts the box end panels label 7 A knob 8 cap 8 A BNC connector 9 A potentiometer Step
15. head 2007 FSM User Guide Page 12 of 28 Step 3 Preparing For PCB Assembly Before starting PCB assembly ensure you have the following ds A large clear well lit working area It is easy to lose SMD components by leaning on them blowing them or pinging them with tweezers etc Also having plenty of light makes SMD soldering a lot easier Use daylight if possible A fine tipped soldering iron and some thin solder By SMD standards 1206 packages are huge but they are still a lot harder to solder than through hole components A good pair of tweezers for handling the SMD parts A multi meter If you spot a suspect solder joint or break a track test it and repair it if necessary before moving on Use a PCB assembly jig if you have one Follow these basic tips for a good result 1 Make sure your PCB is clean If you have had your kit for a while the plated areas of the PCB may have started to tarnish This will make it harder to solder A simple way to remove the tarnish is to rub the board with a standard pencil eraser 2 Use only as much solder as necessary particularly with the SMD parts 3 Assemble the smallest components first working up to the larger parts 4 When soldering connections to the power plane some of the heat of the iron will be drawn away When soldering SMD parts it is easier to solder the other end first then do the power plane when you have both hands free 5 When soldering large metal
16. it is accurate from approximately 1MHz to 500MHz but will continue to work up to around 900MHz This wideband response makes it very easy to use the meter for a wide range of measurements without adjustment If a narrower bandwidth is required a band pass filter can be used at the input However be aware that filters are designed to operate into a 50O input whereas the field strength meter has a variable input impedance which will require a matching network for good filter performance see Appendix F for more details The input is protected from excess voltage by a pair of diodes It is important not to overload the input with signals exceeding 3V pk pk 500 attenuators can be used directly on the input connector if required WARNING Never connect a transmitter output directly to the field strength meter input Replacing the Battery The unit is powered from a 9V PP3 battery To replace the battery 1 Remove the bottom panel by unscrewing the 4 retaining screws 2 Slide out the old battery unclip the clip and replace the battery Slide the new battery into the case The end with the battery clip should go in first 3 Replace the bottom panel using the 4 screws being careful not to over tighten the screws Note that the panel is not symmetrical it only fits in one orientation Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 5 of 28 FSM V1 1 Kit Assembly Instructions This section gives step by st
17. iu 4 1 dre atu tA gj 3 9 4 4 od A LA o ra CN rd 4 TP Kei dnm UN ou Big dt ch asi 133 T pals 1 d eh sa hated lat P 4 ALA AA Dr d fan tea i gy iura d iUa d gt M a aci r te AA i DS w ud 7 4 41 a M ADN i Ae nist d daks io 4 4 Act X 44 wood dads A TENA IMA EK cn tad RAS MIT 4 Ki 4145 Ae 4 F 2g ILE S KA ei t t Vi a4 ide LKE Fee diti tp PAS tn 44 uF ati KE Le w GG C AAA Auer Sate Mk e bla LA RIDERE SRANN A Pri eri IN et 4 oh ST ae Hu uo 1S 4 s CA E tal i WE I HET H MEL ME pm A Le gt w n e j es tee ei re ee Te oe Tt ner e e y fe n a e LA e pe E PETIT mA A de ET LE 14 ge k D Uh fA TAR a 14 Ae a S AC P LEVITRA LV SERIE Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 25 of 28 Appendix C2 PCB V1 1 Bottom Side 6 np HIM E o D De SSRTEDES ARTE I AEN E e D e e TET e d ee e 9 5 o Field Strength Meter V1 1 Copyright 007 Dave Adshead Bpesuspy a 99 SIS Ho Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 26 of 28 Appendix D PCB V1 1 Copper Pattern not to scale Top Side peeuspu q 9317007 O om WS Bottom Side Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 27 of 28 Appendix E Top Panel Drill Drawing o 6 8 12 5 All
18. n one orientation Peel the back off the panel label and carefully stick it on the front panel so that it is aligned with the LED display as shown in the finished product photo Check the unit still operates as expected Your Field Strength Meter is complete We hope you enjoyed building this project Issue 1 Copyright Dave Adshead 2007 FSM User Guide Page 18 of 28 FSM V1 1 Circuit Operation How It Works This section describes the circuit operation to help with troubleshooting and for general interest Appendix A shows the full schematic circuit diagram of the field strength meter Power Supply Section TP1 C10 ya Pu 100nF Batt The unit is powered from a 9V battery which is connected to J2 Power is switched on and off by the switch incorporated into the volume control VR2 D13 protects the circuit from an accidentally reversed battery Power flows through D13 into C9 UA is a step down regulator with a 5V output C8 decouples the input of U4 C10 provides bulk storage decoupling for the rest of the circuit TP1 is the 5V test point Log Amplifier Section VCC Intercept Adjust VR1 100K RI UK Ce cu E oooO 100nF L b Ul AD amp 307 REF 100 J1 1 Input 2 I IN4148 2 5 C2 x 100nF e 100nF R5 JI Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 19 of 28 The input signal comes in on J1 D11 and D12 protect U1 from excessive input voltages due to static build up
19. or being in close proximity to a transmitter C1 AC couples the signal to U1 The input impedance at different frequencies is shown in Appendix F U1 is a logarithmic amplifier It produces a DC output that is proportional to the log of the amplitude of the input signal in other words its output voltage represents the signal strength of the input signal Its internal operation is beyond the scope of this document The output is on pin 4 R5 and C3 prevent RF from entering the output of U1 in a high field strength environment C4 decouples the output The voltage on TP2 is proportional to the signal strength at J1 It is possible to use this signal directly for measurements however this is not an option provided by the standard kit R1 and C11 C5 produce a low noise 5V supply for U1 VR1 R2 feed a variable voltage into pin 5 which adjusts the intercept point VR is used to calibrate the scale of the unit LED Bar Graph Section U2 is a self contained bar graph IC It implements all the logic needed to drive 10 LEDs without the need for resistors The LED outputs are driven by current sources programmed to a specific current by the sum of R3 and R4 The ratio of R3 and R4 determines the scale of the bar graph The bar graph output is linear with respect to the input voltage the log part of the job has already been done by U1 Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 20 of 28 U2 is powered directly from the
20. parts turn up the iron temperature if possible and use a large bit then use molten solder to spread the heat more evenly Oh and remember not to touch the hot component for quite a while 6 Observe anti static precautions 7 Most importantly take your time A Tale Of Two Sides Conventional through hole PCBs have a so called Component Side and a Solder Side Most surface mount PCBs including this one have components on both sides Therefore the sides are referred to as the Top Side and the Bottom Side Generally speaking the top side corresponds to the component side and the bottom to the solder side The bottom side only has low profile components SMD resistors capacitors etc and the top side contains larger height components That way the PCB has a flat side making it is easier to handle We will first assemble the bottom side then the top side Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 13 of 28 Step 4 Bottom Side Assembly eo 2 1 ER e E EE EEEE e RORACOLA e eee ee T Field Strength Meter Ul 1 Copyright 2007 Dave Adshead Turn the board so it looks like the diagram above and fit the parts in the following order A fully assembled PCB is shown in Appendix C2 1 Fit resistors R1 22R R2 22K R3 1K0 R4 1K2 R5 2K2 and R6 3K3 Refer to the component identification section for the value markings Fit capacitors C1 100pF 1206 and C8 470nF 1206 IMPORT
21. rect way round The pins may need teasing inward as they are supplied splayed outwards DO NOT use IC sockets U1 must be soldered directly to the board for good high frequency performance and U2 must be soldered directly to the board for thermal reasons 8 Fit C9 C10 100uF and C11 10uF These are polarised components that need to be fitted the correct way round The long lead should be inserted through the hole marked on the PCB legend 9 Fit LS1 Piezo Sounder and L1 47mH Inductor L1 will not push down all the way to the board due to the solder at the top of the component legs near the body 10 Fit J1 BNC Connector Ensure that it is exactly level with the board Issue 1 Copyright O Dave Adshead 2007 indur FSM User Guide Page 15 of 28 11 12 Fit VR2 10K Potentiometer Remove the nut and washer and discard them Then prepare the shaft by sawing off approx 4mm in length this allows the knob to fit flush to the top panel Solder the component ensuring it is exactly level with the board Fit J2 Battery Clip First shorten the lead to remove some of the excess length the lead only has to reach just beyond the base of the unit The correct length is approx 80mm Solder the ends to the board using the 2 pads marked J2 Batt The positive red lead should go to the square pad and the negative black lead to the round pad Step 6 LED Assembly The LEDs go through the slot in the front panel and
22. s a high voltage transistor C7 shown in the power supply section decouples U3 Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 21 of 28 Appendix A FSM V1 1 Schematic LS1 PIEZO SOUNDER EN C x L1 47mH e 2 C4 PIC12F675 1 U3 S Si 3 oZ 9 s Oz L El M 5 z SJ E 8 SS y ao s i AZ m i d EGE T 2 SB p i l EK E ri i E 9 S Boc Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Appendix B1 PCB V1 1 Parts List Part Type Footprint 22R 1206 22K 1206 1206 1206 1206 1206 PRESET Vishay 148 Series SW 1206 1206 1206 CAP RAD 2 5P 6 5D IND RAD 3 5P 7 5D LED SQ 5MM DIODE 0 3 DIODE 0 4 TO 92 DIP 8 DIP 18 SO 8 TO 92 BNC LP R A PCB Mount PP3 battery clip 1mm scope loop test point red 1mm scope loop test point white 1mm scope loop test point black Piezo sounder Page 22 of 28 Qty Part Number l dl od FN 923 6686 RS 223 2041 FN 924 1027 RS 223 2439 FN 924 0942 RS 223 2265 FN 923 6821 RS 223 2271 FN 924 0969 RS 223 2300 FN 924 0977 RS 223 2338 RAP 67 0245 FN 122 7542 RS 484 9180 FN 855 7250 FN 360 6077 RS 264 4056 FN 644 316 RS 464 6852 FN 128 8280 RAP 11 0245 FN 945 1188 FN 107 7047 RAP 56 1855 RS 229 2576 FN 114 2620 FN 956 5124 RAP 47 3130 FN 956 4993 FN 101 7719 AA FN 948 6500 FN 975 9026 DK MC78LO5BP APMSCT ND FN 95
23. the Shefford Amateur Radio club design which in turn is based on the AD8307 data sheet The major addition is an audio output The new circuit and PCB were designed by Dave Adshead for the Cambridge amp District Amateur Radio Club The cases for the kits are supplied pre cut many thanks to Alan Hunter The major parts are shown below i Y MET 1 IE p On Off and a wi Volume Control l BNC Input Connector OM H i rp a pA a i LB oen i 1048m C amp pArc P 1 Cambridge amp District ue 20 dBm Amateur Radio Club 10 LED poa Bar Graph 40 dBm Display FIELD 50dBm STRENGTH METER Speaker Grille Issue 1 Copyright Dave Adshead 2007 FSM User Guide Page 4 of 28 Basic Operation Basic operation is simplicity itself Simply attach a suitable antenna to the BNC input switch on the unit and adjust for volume fully anti clockwise mutes the tone The LED display shows the relative signal strength on a logarithmic scale whilst the tone rises and falls in pitch on the same scale The tone is useful for making remote measurements such as adjusting a transmitter The tone is also useful for more sensitive applications since the pitch change can easily be heard in steps much less than the 10dB LED increments WARNING The tone is loud enough to damage your hearing Do not put the speaker near to your ear Operational Tips The un
24. uctors There is only one inductor Designator Value Issue 1 Copyright O Dave Adshead 2007 FSM User Guide Page 9 of 28 Diodes amp LEDs You should have 10 green LEDs and 3 diodes The diodes are marked with the part number around their body 5mm Square Green LEDs D11 amp D12 1N4148 UI Transistors There is only one transistor It is clearly marked with the part number Be careful not to confuse it with U4 which looks the same MPSA42 Issue 1 Copyright Dave Adshead 2007 FSM User Guide Page 10 of 28 Integrated Circuits You should have 4 ICs They are all marked with the part number ADB8307A 0536 735717 1 j E m M pee EN U2 LM3914 3 JU PIC12F675 Programmed U4 78L05 There are no IC sockets U1 must be soldered directly to the board for good high frequency performance U2 must be soldered directly to the board for thermal reasons U3 is mounted on the bottom side of the board and must be soldered directly to the board to maintain clearance from the box Issue 1 Copyright Dave Adshead 2007 FSM User Guide Page 11 of 28 Other Components These are the remaining components for the PCB J1 BNC LP R A PCB Mount 2 J Battery clip Test Points ABT 430 RC Piezo Sounder In addition you should have the parts shown in Appendix B2 Additional Parts all of which should be easily identifiable Issue 1 Copyright O Dave Ads
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