Transcript Document
Intermediate Course 23/08/2014 This week.. • Introduction to Intermediate Course • Safety • Soldering • Construction of Simple DC Circuit Introduction to Intermediate Course Week 1 Week 2 Week 3 Week 4 Club Night Week 5 Week 6 Week 7 Session 1 Session 2 Session 3 Session 4 Session 5 Session 6 Session 7 Session 8 Exam Exam & Revision 23/08/2014 30/08/2014 06/09/2014 13/09/2014 16/09/2014 20/09/2014 27/09/2014 04/10/2014 TBC Hour 1 (Theory) Intro, Safety, Soldering Technical Basics / Components pt 1 Technical Basics / Components pt2 Recievers Measurements Operating Practice EMC, Propagation Antennas and Feeders 30minutes revision Hour 2 (Practical Items) Simple DC Circuit Measure resistors Diode and Transistor Project VFO revision Exam Transmitters 13A plug / PL259 Introduction to Intermediate Course • 50 Watts of Power – but note there are exceptions! • Microwave Frequencies: 1.3GHz (23cms) - 250GHz • Unattended Operation • Fast Scan TV • Build your own Transmitters • Some remote control Introduction to Intermediate Course • Intermediate has more frequencies. • Note the exceptions on power limits, and geography • Some are ERP limited freqs • Not all are 50W • Provided in the exam, remember to use it. Safety • • • • • Soldering Use of hand tools Working at heights Electricity RF Safety • Soldering Keep soldering iron in stand to avoid contact with skin when not in use. Make sure soldering is done in well ventilated areas. Avoid breathing in fumes as they can cause breathing problems particularly to asthmatics. Eye protection MUST be worn to avoid solder splashing into your eyes. Safety • Use of hand tools. Work in tidy area, away from body to avoid injury. Handle tools with care. They can cut face or hands if used incorrectly. Secure any items if you are to saw, drill or file them. Items can spin when drilled or slip/move while being worked on which can cause injury. When using a drill ensure the chuck key is removed before using it, else it may fly off! Safety • Use of hand tools. Cont… When drilling protective eye wear MUST be worn to avoid swarf from hitting your eyes. Use a centre punch when drilling to help prevent the drill slipping when making the hole. Bench mounted drills are safer to use than hand drills due to them, allows you to keep Hands well away from danger area. Also gives more control. (Still need to wear eyewear And remove chuck). Safety • Working at heights When working from ladders you MUST have a ratio of 1:4. Example. Ladder in image is 1m away from the wall and 4m high. Make sure when using a ladder that it is; 1. Secured at the top or held by an adult at the bottom to avoid slipping 2. Do not over reach, you don’t want to fall off. 3. Hard hats should be worn when working at height or around others working at height 4. If you are going to need tools while working at height its best to wear a tool belt or another tool carrying device. Also prevents objects falling. Safety • Electricity Take note of overhead cables when using ladders and putting up antennas. Either can either cause arcing or come into contact with cables and will result in a dangerous shock Use the correct fuse. Remember Current = Power / Volts, where Volts is 230v. Example 120watt PSU – 120/230 = 0.5 Amps Residual Current Devices (RCD) gives you better protection then just using conventional fuses. RCDs will detect currents to earth of about 30mA where as a fuse will only blow at several amps And only when there is a short circuit. (Live to Neutral or Live to Earth) Remember if you are to work on equipment which has large or high voltage capacitors you need to discharge Them first, as they can store dangerous electric charges. Safety • RF The main health effect of exposure to electromagnetic radiation is heating of body tissue. Guidance on safe levels of RF radiation is available from government and international bodies (HPA – Health Protection Agency and ICNIRP- International Committee on Non-Ionising Radiation Protection) DO NOT look down a microwave frequency waveguide or to stand close to or in front of high-gain antennas as they may be in use. Your eyes are vulnerable to heating. The focus of the waveguide Of a microwave enhances the heating effect to a smaller area of the body. Soldering • What is soldering? Soldering is a method of joining metal wires and components using a hot soldering iron to melt the solder Solder contains flux which is to help the solder flow and to prevent a layer Of oxide forming on the areas being joined. Not all metals are easy to solder. Tin, copper, and brass solder well, where As aluminium and stainless steel require special techniques. This usually will Not be a problem when building circuits or soldering PL259s for example. You should always keep the soldering iron tip clean. This is to remove oxide. To prevent oxide and to help the heat conduction, the iron tip should be “tinned”. This is why you should tin wires before soldering them onto connections. Soldering When making solder joints they should be made reasonable quickly to avoid damage to components. Leaving the iron on the joint too long can cause “cold/dry” solder joints. • Construction of Simple DC Circuit Materials and Components • • • • • • • • Block of wood 10cm by 10cm Small bulb holder Bulb Resistor (R1) 2.2ohm – Red Red Gold Resistor (R2) 470ohm – Yellow Violet Brown Drawing pins x 5 AA battery holder Single Core wire (around 20cm) SEE PAGE 8 in your book. • Construction of Simple DC Circuit Layout Push into the board the pins In the layout shown. • Construction of Simple DC Circuit Solder R1 and R2 Place Bulb holder on board • Construction of Simple DC Circuit Layout Solder into place the four wires Notice the wire in the bottom right Is only solder to one pin. • Construction of Simple DC Circuit Layout Solder on the Positive (+) and Negative (-) wires from the battery holder • Construction of Simple DC Circuit Layout Put Batteries into holder and put Bulb into holder • Construction of Simple DC Circuit Layout Touch wire to pin to create the circuit • Construction of Simple DC Circuit Layout Make sure you put your name on the Board. G F A Also label up the board. E B Paul M0PFX X Y D - + C • Next Week Technical Basics and Components Part 1 Measuring Resistors..