AWA Newsletter # 92 September 2013 Affiliated Reflections: to the SARL How quickly this year Soon we will be looking at systems. It keeps you thinking seems to have flown by the end of another year and about what's going to happen again. It seems like just last the exciting beginnings of a next. Antique week we were talking about new year. However, we will not allow projects for the year and Wireless We will make all sorts of this to negatively influence what would be easily attain- Association of New Year resolutions, make our thought patterns and mo- able goals. Southern Africa a whole lot of promises to tivation, or lack of, but be sure I know that I for one spoke ourselves about what we that it will kept he grey mat- about the various little pro- would like to achieve again, ter under some duress and jects I wanted to get going and then watch them slowly make sure that it continues to Inside this issue: and how I was going to erode into nothing—again. function in the right way. As tackle them one by one. some would say, that we keep Maybe this just happens CW Net 2 firing on all cylinders. Well, three quarters with me and most others are SSB Activity 2 through the year and I able to complete all the pro- Definitely not the time to drop haven't even managed to jects they have started and down in to the depths of des- complete one of them. resolutions that have been pair and give up on life com- AM 2 put forward. Maybe its just pletely. After all, what is life I think I will give up trying me that cannot get around to without something to look to set dates to have things even starting to think about forward to ? Microphones 3-5 finished by and just tackle completing projects, but I (Continued) things one at a time until it Even if it is just to be able to seriously doubt it. is finished, and then go to talk with a bunch of like Presidents Corner 6-7 the next one. Who cares Anyway, it makes life inter- minded radio enthusiasts who how long it takes. esting to keep making prom- take pleasure in watching ises to yourself that you nev- valves glow in the dark Cyclic QSB 8-9 I realise of course, there are er know you will achieve. It many other things which must be part of our self de- Notices 10 take preference to my de- structive mode that many of Best 73 sires to finish some of the us have in built in to our projects in my shack. DE Andy ZS6ADY AWA Committee: WIKIPEDIA High Power Triodes: ∗ President—Richard High power triodes, in contrast to low power ZS6TF triodes, often have a linear construction, with a circular flat cathode, grid, and plate in a ∗ Technical Advisor—Rad line along the axis of the tube, to reduce inte- ZS6RAD relectrode capacitance and allow better heat ∗ removal. Tubes with plate power dissipation Secretary/PRO— over about 350 W must be actively cooled. Andy ZS6ADY The plate electrode, made of heavy copper, projects through the wall of the tube and is * Western Cape—John attached to a large external finned metal heat sink which is cooled by forced air or water. ZS1WJ The envelope of the tube is often made of more durable ceramic rather than glass, and all the materials have higher melting points Radial heat sink with thermal profile and swirling forced convection flow trajectories predicted using a CFD analysis to withstand higher heat levels produced. package Page 2 AWA Newsletter CW Net: One again, it has been a fairly mediocre month Unfortunately I have not had the opportunity to going for a number of years, with a band of of CW on the bands with one or two excep- get back in to the shack about the same times stalwarts who enjoy using straight keys and tions. again, but am certainly looking forward to the generally enjoy CW. opportunity to do so. The majority of times, the AWA CW net pro- I raise my hat to you guys. Thank you for keep- vides a lot of activity on the band. There are the As far as I am aware, the QRP group still meet ing the interest going and keeping me in tow. regulars who call in on a Saturday afternoon every morning on 80m on 3579 and then there DE ZS0AWA/CW and every now and then there will be a new call is the Cookie net every afternoon at 14:00 dur- sign of someone who was just passing through. ing the week. There is always DX to be found on the 20 and So if you feel like playing some CW at those 15 meter bands and sometimes even on 40m. times, there are people around on the bands to satisfy your needs. I was surprised the one evening to hear a FH8 station calling on CW and went back to him to The AWA net was started with the idea of be- get a 599 report. Thereafter I had a few good ing a slow speed net to encourage others to contacts with some Cape stations who were come along and first timers to get in to some booming in 589. CW, as well as enticing those who had let it slip for a couple of years and felt they could still do This was the exception to me during this time a decent bit of pounding the brass. of very low activity on the local bands and what a pleasure it was to be able to work Div 1 under Unfortunately, the net has not been that suc- such good conditions. cessful in its aims, but still has managed to keep SSB activity: There is still a general increase in interest for everyone to discuss or add their own National net at 08:30 on 7140, net controllers again with the SSB net on Saturday morn- comments. normally to look out for are ZS1WJ or ings. ZS1MJJ. Band conditions are usually very With our President, Richard ZS6TF, having favourable for their net. Who knows why the trends happen the way been away for his winter break, the topic they do, but during the winter months there idea has continued and though a bit difficult is generally a drop in numbers calling in to to think of reasonable topics for discussion, the net, but as summer approaches, it tends to has certainly proved worthwhile. pick up again and we are back to around 18 Band conditions continue to be fairly good, to 20 people calling in again from around 10 even down to the Western Cape at that time to 15 in the winter. of the day, but start to fade fairly quickly. Whatever it is, its always good to hear the The rest of the divisions seem to do quite old call signs coming back again and the well throughout the duration of the net. interest in the topics been shown. The Western Cape net is run on a Saturday There has been such a variation in topics morning before the National net and also has over the last year and most of them have a fairly good attendance from all those inter- Yaesu FT200 generated a good response with a lot of inter- ested parties in that part of the world. Look esting comments and ideas being thrown out out for them on 3625 or 7070 before the AM: The AM net still runs at its usual times on It would be nice to think that the AWA has Do come along and join us at around 06:00 Saturday morning and as the summer condi- definitely played a big part in encouraging on 3615 on a Saturday morning and make tions start to come in, the band opens a little many people to restore the old valve rigs your self known. earlier each Saturday morning. that are heard on the air today. This of course Give us a signal report and let us know how is the purpose of the AWA. The net is still well attended by the regular the AM is getting out. group of AM’ers and the standard of AM Often rigs are donated to the AWA which transmissions is as good as one could expect would otherwise have been destined to scrap it to be. The real old timers and original AM heaps and junk yards and these have been guys would be very pleased with what they restored to former glory and are used with hear. great pride by the restorers. As well they should be. And well they should be because the majori- ty of transmitters used are probably the same If you have an interest in restoring any old as those originally used when only AM was AM transmitters, but don't know where to available. Before the days of SSB that is. get hold of one, then contact one of the com- mittee members and they will be able to put The musical transmissions still tend to be a you in contact with someone who would draw card for the AM listener, and of course probably be able to assist. Many of them are quite a privilege we have here in SA. also keen collectors. Central Electronics 100V Page 3 AWA Newsletter Microphones (Continued from Issue 91) Speakers as microphones A loudspeaker, a transducer that turns an electrical signal into sound waves, is the functional opposite of a microphone.