VLF Kit Assembly Manual
Contents
1. Astronomy Association Very Low Frequency Receiver Kit Assembly Manual www ukraa com The UK Radio Astronomy Association Company Limited by Guarantee Reg No 6481611 Registered Charity No 1123866 Astronomy Association Acknowledgements Design Team The UKRAA VLF Receiver design is a combination of public domain material and original improvements by BAA members John Cook and Peter King The circuit board layout was undertaken by John Cook Contributors The following authors have contributed to the VLF Receiver Kit Assembly Manual Andrew Lutley Alan Melia Dr Laurence Newell Norman Pomfret Issue 1 2010 January 1 UKRAA Table of Contents Jeer er E 3 II D A EE 3 The UKRAA e E 3 leg re A BEEN e EE A EE 4 Printed ircult Board EE 5 SSS NORN disce to RTT 5 Pies installed Compnbg Is uu s ul Rub 6 total the AR OPER iae cuc nente lee tette tate dt a due te eet nance al 6 nsa E EE 8 Gee AS LECT uui beienee Beete KEE EE 9 T le E 12 Eeler 12 EE L HERE 13 E E 13 EE uuu au Ee 13 Some Further OVIEE uuu i iba po eoe tue ccn ocio te utu Up e e DN dni ux tne cu E RES E 14 Examples of Soldered TEE 15 SE LE 17 Eeer EE M E EET 18 EE ee 18 Append k nl Eer CT BEE 19 Appendix 2 Resistor Colour Codes iua ul EE EES 21 Appendix 3 VLF Receiver PCB Layout sssssss2. UKRAA Printed Circuit Board PCB The photographs below show revision 5 of the VLF Receiver circuit board Component Side Solder Side All components are inserted from this side Components are soldered on this side and soldered on the other side Assembly Sequence The assembly instructions will follow the sequence below full details are given in the later sections Inspect the components supplied and check against the list in the Appendix Install the Resistors and Capacitors Bags A and B Install the dual in line DIL sockets Bag D Install the Semiconductors Bag O Test the VLF Receiver Issue 1 2010 January 5 UKRAA The intention of the recommended assembly sequence is to install components in order of height above the board surface Resistors diodes and not electrolytic capacitors DILIC sockets Polarised header plugs and pin clusters for jumpers Electrolytic capacitors remember the polarity is important and the longer wire is the positive lead The variable resistors trimpots mount with the adjuster screws to the rear D 25 end of the board Install the regulators and transistors last and then test before installing the ICs Pre installed Components The surface mounted temperature sensor chip IC7 has been pre installed on the component side of the PCB Install the Resistors Remove the fixed resistors from Bag A 4Hu1 Fixed resistor
3. 3 UKRAA Assembly Instructions The following assembly instructions should be followed carefully The VLF Receiver is not a simple electronic assembly and is not regarded as a project suitable for a beginner If you follow the instructions carefully you should be successful in building a VLF Receiver that works If you are not careful you run the risk of having a problem that may be very difficult to locate and fix later If you are in doubt about your abilities you are advised to seek out a local electronic hobbyist or Radio Amateur with constructional experience It is recommended that you read these instructions right through before commencing on the construction of the kit You may need to prepare for some of the ideas suggested later in the text before you get too far into the construction It is appreciated that experienced constructors will have developed their own techniques but we suggest you think carefully before diverting from the sequence suggested Tools Required Wire cutters Needle nose pliers Soldering iron low voltage 24V iron preferred at least 15 25 watt small tip 25 to 40 watt is better Light duty resin core solder 22SWG or 0 8mm Sponge Magnifying glass Solder sucker or solder wick Kit Contents Printed Circuit Board PCB Bag A Resistors Bag B Capacitors Bag C Semiconductors Bag D Connectors sockets and miscellaneous hardware Issue 1 2010 January 4
4. The resistors have the values written on each plastic bag If in doubt the value of resistors is given by the colour coded bands see the section at the end if you are unfamiliar with resistor colour codes The resistors supplied are all five band 1 tolerance It is suggested that the variable resistors trimpots VR1 4 should be installed later after the small ceramic capacitors have been soldered in Resistor locations are marked on the component side of the PCB with the symbol R followed by a number R1 R2 etc Issue 1 2010 January 6 UKRAA The following table indicates the values of the resistors Identification Quantity Resistance R1 R2 R5 R6 R7 R8 R9 R10 R12 R16 R19 R20 19 10k R23 R24 R25 R26 R27 R28 R29 R3 R17 2 1M R4 1k R11 R18 R21 R22 4 100k R13 8 2k R14 R15 2 47k To prepare a resistor for insertion into the PCB bend the two leads so that they form a right angle to the resistor body the wire spacing allowed for insertion is 0 3in Bending resistor wires prior to insertion Do not bend the leads close to the body of any component because it may damage the lead anchorage To install place the leads of the resistor through the appropriate holes and press the resistor down against the component side of the PCB There is no required orientation for resistors either lead may be inserted in either hole Turn the board over while holding the resistor in position and bend the leads s
5. and return to visual inspection of the PCB If the current draw is correct remove the power and disconnect the DMM Ensure that VR4 is wound fully anti clockwise wind 15 turns to be sure there is no end stop Re connect the DMM to read the output level on P10 Place a short across the aerial terminals P1 Re connect the power leads direct to P2 and apply power The output level should read about 0 2 to 0 25 Volts on a PCB with a strap at R29 2 5 Volt range setting It the reading is higher or much lower there may be a problem Remove the power and repeat the preliminary tests before proceeding with detailed fault finding Proceed to the Tuning stage This becomes part of the testing because successful tuning indicates correct operation of the unit Soldering Guide Technique IMPORTANT DO NOT leave a soldering iron plugged in for a long time without using it NEVER leave a hot soldering iron unattended Issue 1 Clean the tip of the iron by wiping it on the damp sponge It should be tinned with a very thin coating of solder The sponge will remove excess and any slag Place a small amount of solder on the tip this should NOT form a big blob and is NOT for making the joint but will help to convey the heat of the iron to the joint Hold soldering iron firmly down against the copper track and against the side of the component lead so that the track and component lead are BOTH heated about two seconds 2010
6. component side of the board Since you pulled the legs out that way you should have a dome of solder on that side whereas the solder surface in the hole on the other side may be below the board surface A fairly large chisel bit is best for the following operation rather than a conical point Take some solder braid use good quality Multicore if you are right handed place the reel or the slack on the right of the PCB and hold the end in your left hand Place the last used part of the braid yes that bit filled with solder over the hole to be cleared fill the soldering iron bit with a blob of of new solder and place it on top of the braid and over the hole When you see the solder start to flow pull the braid away across the hole under the iron keeping the iron over the hole The solder should wick out of the hole and fill the braid as you move it away Stop pulling when no more solder enters the braid and quickly remove the iron When you remove the braid and iron you should now see a clear hole The secret is to use plenty of new solder to engulf the old solder in a pool that you then draw into the new wick The new wick appearing over the hole tends to keep it cooler as well If you work from the component side of the board there is less chance of damaging tracks if you do get things too hot If it doesn t work first time allow the hole to cool for a bit before trying again Be careful when using the hole again and inserting a component rememb
7. corresponding to the first resistor identity on the bag label e g RI and after dressing the leads install in the appropriate holes Be careful correctly identifying such as R6 and R8 and R 16 and R18 Multi pin components can easily not to fitted snug to the board because to slip out slightly when the board is turned over for soldering If you do not use a jig see a later section for a description of a simple aid solder just one pin the inspect the top side of the board to see the component it fully home against the board surface The polarised header plugs are easy to mount slightly skewed but correct neat assembly will enhance your satisfaction with the finished unit If you use the foam aid to hold the components it is suggested you place a jumper on the unpolarised jumper pins or they just perforate the foam and are not held tight It is possible that some components maybe supplied due to ordering difficulties with slightly different lead spacing specification The lead spacing can be altered carefully with a pair of narrow nose pliers Try not to bend lead too close to the components body because it is possible to damage the component The most sensitive to this form of damage are the glass encapsulated diodes The wires should not be bent closer than about 2mm to the body of the component to prevent fracturing the the lead to glass seal Issue 1 2010 January 14 UKRAA Examples of Soldered Joints Making good soldered joints is vital
8. header amp links UKRAA Appendix 2 Resistor Colour Codes 5 Band Code 237KQ 1 2nd circle 3rd circle 4th circle 2nd figure 3rd figure number of zeros CR oM o 1 E CONSE CNN 2 EE omm om NH EE EE oE 1 2E ss 1st circle 1st figure 5th circle tolerance SR SS s ON GR cM CMs Em o Wall 8 8 8 e sr s x0 1 4 Band Code Resistor Colour Code Chart Issue 1 2010 January 21 05 s aay oom d 47KQ 5 UKRAA The following table indicates the values of the resistors Colour Code Identification Quantity Resistance First 4 colours R1 R2 R5 R6 R7 R8 RY R10 R12 R16 R19 R20 R23 R24 R25 R26 Brown Black Black Red R27 R28 R29 2 Brown Black Black Yellow es ane Pe ae ae Brown Orange Note that the colours are always read with the first colour nearest the edge of the component as shown above This is not easy to determine with the resistors supplied but they are all five band 1 tolerance so will all have a brown ring at one end Sometime it will be necessary to use the resistance range of your multi meter to gain confidence you have the right value Issue 1 2010 January 22 UKRAA Appendix 3 VLF Receiver PCB Layout F 2 Id 9 3104d 31HY N3 TE EI GS Lll Sd ooo 600z vvinin OJO oo CH OOOOOOOOOOOOO 2 Ou e E m o
9. header pins before strapping the foam over them Using this method you can insert several components and solder them in position secure in the knowledge that they will stay properly seated against the board Just be careful not to touch the elastic bands with the soldering iron or everything may fly apart Soldering Assembly Frame side view Issue 1 2010 January 17 UKRAA Cleaning the Circuit Board You may wish to remove any solder flux residues left after soldering There are products available for this purpose as liquids or aerosols Depending on the solder you have used it may also be possible to use water as the solvent alternatively cellulose thinners can be used for a faster effect Scrubbing with a stiff brush even an old toothbrush may be all that is required Correcting Mistakes If you have to remove a faulty or misplaced through hole component remember the PCB is worth more than the component Chop up the component usually through the body to leave as long a lead as possible and enable you to remove the leads individually This can be done usually without getting the board too hot for the through hole to be damaged However this often leaves you with a solder filled hole There are all kinds of solder suckers but these can be difficult to use particularly on ground plane holes and sometimes difficult to keep tinned and keep the joint hot enough The following technique can be successful if done carefully Work on the
10. jumpers on the OUT side of P11 and the XI side of the DC GAIN header pins A further jumper may be placed on the PROTECT side of header P5 Resistance Tests It is suggested that any general purpose Digital Multimeter DMM can be used for the following tests Issue 1 Measure the resistance between the wire clamping screws of P2 The initial reading should be at or above 10kOhm and should drift slowly upwards to around 90kOhm or higher as the large electrolytic capacitor charges up Ideally your positive probe should be on the screw nearest to IC5 to ensure the electrolytic capacitor charges with the correct polarity If the reading is below 5kOhm repeat the visual inspection looking for stray wires or solder splashes between pads 2010 January 12 UKRAA Power up Tests Assuming the results of the above tests are satisfactory insert the ICs taking care to orientate them correctly with regard to the indent on the socket Check carefully down the side of the IC sockets magnifying glass after insertion to ensure that all the IC pins have entered the socket and there are none bent up underneath the package Arrange a 15 Volt DC power source and connect to P2 but connecting the DMM in series with the positive lead to the positive terminal of P2 and select direct current measurement on the 200mA range on the DMM Apply power and check that the current draw is around 30mA If the reading is above 50mA or very low remove the power
11. labelled 103 and the 100nF labelled 104 You may need the magnifying glass to read these numbers Install the ceramic capacitors using the same technique as for the resistors It is easiest to install the shorter components first leaving the tall components until later in the sequence Issue 1 2010 January 8 UKRAA Thus fit the electrolytic capacitors last Once again it is suggested that one type and value is selected and all these are installed before moving on to a different value Only the electrolytic capacitors have a polarity that must be observed and the PCB will be marked with a to indicate the correct orientation Where there is no fixed orientation it is usual to choose an orientation for the capacitors that allows their value to be easily read when installed Now install the taller electrolytic capacitors observing the polarity marking on the board The longer of the two leads is the positive lead but there is also a grey band up the sleeve with a on the side nearest to the negative lead Miscellaneous Variable Resistors Variable resistor multi turn The components supplied do not have offset wires so unlike the one pictured can be installed in reverse This will affect the tuning direction of the adjustment screw If the adjusting screw is located so it is towards the rear of the board the 25way connector P4 it should be in the correct orientation Sockets It is suggested you next insta
12. o o O o D o o o OOOOOOOOOOOO O VLF Receiver Component Overlay UKRAA 23 2010 January Issue 1 it Diagram IrCul Appendix 4 VLF Receiver C 623 LM HS ONY 82a LIW PZ I NO NIY ALINN 303 ZHX3S ZHX2 1 abuey 6002 vin UOI5J9A AeAja23M ITA 9 8dq181S dno15 urouoJ1sv otpey id g vas 158 ag WHOIS wn a TTYTTTTTTTTTT S20 31T1081LN03 19S WNOIS vYIv 32012 NI THO Ted d AQ Zef d L s48fho Bioub 2 er TZ 5 90 ON SSA vaat im x op Er LI i3u raves tH NGHS SHJ SHI 88152 THI d m Lnogm H E r e 22 TH p 4195 H B Gei 673 b gor Crag se dt gt NI NIQ TTaO AflO ino Zec4 LAG 4 Tedd ino 2700 Ten Zeta Cage Te td 3311081805 ed OL LNO 23MOd tesa NI 33404 ASI Zeza Ted saiat 5 QC 3THYN3 d BT ABT Bed gq au nbaaj ACEL Cela D 2B NT a UKRAA 24 2010 January Issue 1 Appendix 5 Regulatory Compliance RoHS The Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment 2002 95 EC commonly referred to as the Restriction of Hazardous Substances Directive or RoHS was adopted in February 2003 by the European Union The RoHS directive took effect on 2006 July 1 and is re
13. January 13 UKRAA After the lead and the contact have heated apply the solder to the lead and copper track NOT directly to the iron until the solder melts and flows around the lead and into the contact Remove the iron This should leave a gently dished meniscus like water in a glass showing that the solder has wetted the joint and thus made good electrical contact A lumpy or crystalline look to the joint suggests that the joint is dry and will not make a reliable electrical contact In such case it should be carefully reheated with the iron and perhaps a very small about of solder until the required meniscus is formed The inability to form this meniscus easily suggests that the iron may not be hot enough or possibly is not tinned properly Do not apply so much solder that it runs across the PCB surface Allow the joint to cool and inspect the joint Trim the excess lead wire just above the solder joint If too much solder has been fed into the joint and it resembles a blob the excess may be removed with the solder wick or solder sucker The joint can then be inspected for correct wetting under a magnifying glass Some Further Advice It is recommended that you install the resistors first the easiest way is to take a bag which will contain the same value resistors you may wish to check the colour code against the table at the rear of the manual select one and identify on the PCB the position to
14. er it is slightly smaller than original because there will be a thin film of solder over the inside If you do damage the pad on the component side it does not matter too much because the connection will be made on the solder side of the board and it can easily be patched if necessary Issue 1 2010 January 18 UKRAA Appendix 1 Component List Identification Bag A R1 R2 R5 R6 R7 R8 R9 R10 R12 R16 R19 R20 R23 R24 R25 R26 R27 R28 R29 R3 R17 R4 R11 R18 R21 R22 R13 R14 R15 VR1 VR2 VR3 Bag B C12 C4 C5 C3 C13 C1 C2 C8 C14 C15 C16 C18 C19 C7 C10 C6 C11 C9 C17 Issue 1 2010 January Qty 19 2 N N OO 19 Component 10k 1M 1k 100k 8 2k 47k 10k 10 turn variable resistor Int Ceramic disc 1n5 196 Polystyrene 10nF Ceramic disc 100nF Ceramic multilayer 1OuF 25V Electrolytic 100uF 25V Electrolytic 220uF 35V Electrolytic 4u7 63V Electrolytic UKRAA Bag C IC1 IC2 IC3 IC4 IC6 IC7 IC8 TI T2 D1 D2 D3 D4 Bag D IC1 IC2 IC3 IC4 IC5 P1 P7 P9 P10 P2 P3 P5 P6 2 P11 DC GAIN Issue 1 2010 January 20 TLO84 amplifier LM324N amplifier 24LC512 P EEPROM ICL7662 regulator 12V regulator 7812 LM73 Temperature Sensor pre installed 5V regulator 78L05 BC547 transistor BF244A JFET 1N914 diode 1N4004 diode 14 pin socket 8 pin socket 20 pin IC socket 2 way plug amp socket pairs 2 way terminal block 3 way
15. in through the slot in the shell whilst applying a gentle pull to the wire You may require a new crimp though with care they can be re soldered The interconnections are covered in the main manual F B 2 pin headers DE Ww oH Y Headers SE for shell 2 way terminal block m A selection of Hardware Identification Quantity IC1 IC2 2 14 pin socket IC3 IC4 2 8 pin socket IC5 1 20 pin IC socket P1 P7 P9 P10 4 2 way plug amp socket pairs P2 P3 2 2 way terminal block P5 P6 2 P11 DC GAIN 6 3 way header amp links P13 Issue 1 2010 January 11 UKRAA Testing Visual Inspection Start with a completed PCB with no ICs installed Check that the appearance of all soldered joints is satisfactory and there are no wires or pins that have been missed A correctly made joint should reveal the end of the though board wire or pin This must not be hidden inside a spherical blob of solder Check for a wetting meniscus on the sides of the through wire see diagram Check all electrolytic capacitors and diodes are inserted the right way round The grey band with a black denotes the negative lead The band on the diodes should match those shown on the layout diagram Check all the IC sockets are oriented correctly with the indicator slot in the correct orientation see the layout diagram Check the orientation of the transistors T1 and T2 and IC6 note the position of the flat on the moulding Place
16. lightly outward to hold the resistor in place and solder the leads to the circuit side You may find it convenient to insert all the resistors with the same value first and then move onto the next value This avoids errors due to a wrong resistor being installed and also avoids having to continually refer to the colour code charts in an Appendix which can be hard on the eyes once the resistors are removed from the bandolier tape Issue 1 2010 January 7 UKRAA Several resistors may be loaded at the same time and retained by splaying the leads slightly where they come though the PCB They can then all be soldered at the same time See the section below describing how to make a simple assembly frame It is suggested that you use the component list as a guide and cross off the resistor as you locate its correct position and mount it It may be useful to do the same on the layout diagram It then soon becomes clear which components you have yet to install and makes locating their position much easier Install the Capacitors Remove the Capacitors from Bag B Identification Quantity Capacitance Value C12 1 1nF Ceramic disc C4 C5 2 1n5 1 Polystyrene C3 C13 2 10nF Ceramic disc C1 C2 C8 C14 C15 C16 C18 C19 8 100nF Ceramic multilayer C7 C10 2 10uF 25V Electrolytic C6 C11 2 100uF 25V Electrolytic C9 1 220uF 35V Electrolytic C17 1 4u7 63V Electrolytic A selection of Capacitors The InF disc capacitors are labelled 102 the 10nF
17. ll the sockets Bag D Take care to install the IC sockets the right way round since the orientation mark on the socket will serve as a reference to the correct orientation for the insertion of the IC Issue 1 2010 January 9 UKRAA Semiconductors Remove the Semiconductors from Bag C Be careful with the orientation of IC6 the double line in the screen print signifies the metallic back Similarly ensure that the flats on IC8 and on T1 and T2 align with the screen print outline When installing diodes and transistors it is essential that the correct orientation be followed The diodes with their axial leads look very like resistors but the band on one end of the body indicates the negative cathode end and must align with the screen print on the PCB Where glass body diodes have been provided do not bend the leads whilst holding the diode body The lead should be held with a pair of fine nose pliers close to the body to prevent the stress of the bending fracturing the glass Identification Quantity IC 1 TL084 amplifier IC2 1 LM324N amplifier IC3 1 24LC512 P EEPROM IC4 1 ICL7662 regulator IC6 1 12V regulator 7812 IC7 LM73 Temperature Sensor pre installed IC8 1 5V regulator 78L05 TI 1 BC547 transistor T2 1 BF244A JFET D1 D2 D3 3 1N914 diode D4 1 1N4004 diode Note that IC5 the MAX186 Analogue to Digital Converter is an optional component which may be fitted if Radio Sky Pipe compatibility is required The i
18. mage below shows the orientation of the LM73 temperature sensor for your reference Pin 1 is underneath the T of the underlined legend T731 Orientation of LM73 Issue 1 2010 January 10 UKRAA Hardware Some of the header plugs on the board are polarised and the solid line on the screen print signifies the position of the raised polarising peg WARNING The earlier releases of the PCB have errors in the screen printing in that the positions of some of the polarising pegs are not marked This does not apply to revision 5 and later Two pairs of crimp terminals are provided for wiring the connector to the polarised white two pin header plugs Bare some insulated connecting wire and gently close the tangs on the wire with the pliers The bared wire length should be cropped so that the outer tangs grip the insulation whilst the ones nearest the socket grip in the wire The end of the wire should not protrude more than 1mm beyond the lower crimp or it will impede the insertion of the header pin Since it is unlikely you will have the correct crimp tool you should runa small amount of solder into the wire crimp to ensure a good connection The crimp socket is then inserted into the shell But you need to be careful to align the tongue with the slot in the moulded shell When aligned correctly push the crimp into the shell until the tongue engages and the wire cannot be pulled out A damaged wire may be replaced by gently pushing the tongue
19. mited by Guarantee Reg No 6481611 Registered UK Charity No 1123866 27 UKRAA
20. quired to be enforced and become law in each member state This directive restricts the use of six hazardous materials in the manufacture of various types of electronic and electrical equipment In speech RoHS is often spelled out or pronounced rosh The above paragraph was taken from the Wikipedia essay on ROHS The RoHS Directive restricts the use of the following six hazardous substances in electronic and electrical equipment products falling within the Directive 1 Lead 2 Mercury 3 Cadmium 4 Hexavalent chromium 5 Polybrominated biphenyls 6 Polybrominated diphenyl ethers UKRAA confirms that the suppliers of the components and materials used in the UKRAA VLF Receiver have stated that such components and materials are RoHS compliant and that reasonable steps have been taken to confirm these statements WEEE ROHS is closely linked with the Waste Electrical and Electronic Equipment Directive WEEE 2002 96 EC that sets collection recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic e waste The Waste Electrical and Electronic Equipment WEEE Directive is designed to ensure the efficient collection and recycling of electrical and electronic equipment at end of life If a customer purchases a new product from UKRAA which falls within the WEEE Directive to replace an existing one of similar function to the one that has been sold and in
21. ssssssssssssssssssasssaas 23 Appendix 4 VLF Receiver Circuit Diagfrarm unii eai iti bi a p aao HR RR DR SR SA RR RR NR 24 Appendix 5 Repulatory Camplia iee uu od l cl Gui ad eaa Ces a ads 25 LE 26 Revision TE e KS DENT el Ed OT Ee 2T Issue 1 2010 January 2 UKRAA Introduction UKRAA The UK Radio Astronomy Association UKRAA is a non profit making charitable company limited by guarantee It was established by the Radio Astronomy Group of the British Astronomical Association BAA to facilitate the production and sale of radio astronomy products Any suggestions or recommendations for improvement of this Manual would be appreciated See the Contacts page for further details The UKRAA VLF Receiver The UKRAA VLF Receiver is designed to record Sudden lonospheric Disturbances SIDs induced by solar flares It does this by monitoring transmissions from Earth based beacons which are affected by changes in the ionosphere giving an indirect indication of events on the Sun The main motivation for this work is to correlate these radio observations of solar activity with those from optical observers and to follow the cycles of sunspots as they appear on the Sun The VLF Receiver User Manual explains how the unit may be connected to a variety of data loggers and to the UKRAA Starbase networked observatory Please visit www ukraa com for more information on how to share your observations with others Issue 1 2010 January
22. tends to dispose of the existing one then the customer can request that we take back the existing product and deal with the costs and logistics of recycling it Any customer wishing to take advantage of this facility should contact us Provided that the existing product comes within the scope of the WEEE Directive we will make arrangements for its return or collection and will deal with its disposal Issue 1 2010 January 25 UKRAA Contacts The UK Radio Astronomy Association Springfield Rookery Hill Ashtead Park Ashtead Surrey KT21 1HY A Company limited by Guarantee Registered in England No 6481611 Registered Charity in England and Wales No 1123866 E mail info ukraa com Website www ukraa com Fax 0870 132 3728 Telephone 01372 279066 Starbase Information Website www starbase org BAA Radio Astronomy Group Website www britastro org radio Issue 1 2010 January 26 UKRAA Revision History Revision Date Author Status Draft A 2009 08 08 A J Melia Internal draft for peer review Draft B 2009 08 09 LM Newell Incorporated reviewer s comments Draft C 2009 08 11 LM Newell Incorporated reviewer s comments Draft D 2009 08 20 L M Newell Internal draft for peer review Issue 1 2010 01 12 LM Newell Incorporated reviewer s comments Outstanding Work Update component list for release 005 of the PCB Issue 1 2010 January Radio Astronomy Association Li
23. to the correct operation of this unit The pictures below provide a guide to help you inspect your work and correctly assess the solder quality The joint should look like this The solder IS flowing between the component leg ond the copper pod i e wetting the joint Issue 1 2010 January 15 UKRAA A good soldered joint A bad joint looks like this The solder isn t wetting the copper pad and component leg i e it s a dry joint Copper cladding i e etched track Fibre glass laminate PCB Component ieg leg Issue 1 2010 January 16 UKRAA Simple Assembly Frame The insertion of wire ended components is fairly straight forward in that they can be retained in position whilst turning the board for soldering by splaying the excess leads out Other components like headers and sockets with more solid connections are more difficult Professional assemblers use a frame which allows all the components to be inserted and held on position against the PCB by a foam block whilst the frame is rotated to offer up the solder side of the board A very simple version of this may be easily made with some foam a piece of thick cardboard or hardboard and a couple of elastic bands The only caution is that the pins of the headers may get hot during soldering and some foam may melt at quite low temperatures The easy way to avoid problems like this is to insert the jumper on the component side of the
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