English Version - Malta Amateur Radio League
Contents
1. vn 2011 Tpejjipx Smoking is prohibited s at the Centre From the Editor Friends I welcome you to another issue of this magazine for April 2011 which is issue 62 of this series I also remind you that MARL is going to take part in the Spring Fair that is going to be held at San Anton Gardens on Saturday and Sunday 14 15 May 2011 You have further information on the frequencies that are being used in the Libyan issue if one wants to listen to what is happening We are still trying to be given an allocation on the frequency of 500 kHz to be able to communicate with radio amateurs from a number of countries that have given an allocation on it to their radio amateurs You have two photos of the dishes used by Joe 9H1VW and Mansueto 9H1GB during their tests on 10 GHz Note that Joe 9H1VW was screened by the Madliena hill Today you have the last information on electrical plugs that are used in different countries The voltage that one finds in the different countries as well as the frequency which nowadays is 50 Hz or 60 Hz are going to be in the next edition of the Magazine As you know a controversy has been going on for some time ever since cellular telephony masts have started appearing on roofs on whether radio frequency radiation causes harm to persons I am therefore going to start giving you some information on how you can take precautions to protect yours and others health Also don t forget that according to the l2. 4196 0 kHz NATO Net Primary Very Active 5368 0 kHz Libyan GMMRA ALE Network 5725 0 kHz UK Royal Navy 6688 0 kHz French Air Force Very Active 6690 0 kHz Several players over No Fly Zone 6712 0 kHz French Air Force 6733 0 kHz UK Royal Air Force 6761 0 kHz USAF Global Aerial Refueling Operations 6877 0 kHz USAF PsyOps from Commando Solo III 6884 0 kHz Libyan GMMRA ALE Network 9019 0 kHz UK Royal Air Force 9031 0 kHz UK Royal Air Force 9375 0 kHz Libyan GMMRA ALE Network 10125 0 kHz Libyan GMMRA ALE Network 10315 0 kHz German Air Force 10404 0 kHz Libyan GMMRA ALE Network 10405 0 kHz USAF PsyOps from Commando Solo III 12311 0 kHz French Air Force 14583 5 kHz French Navy 16160 0 kHz French Air Force 245 8500 MHz UFO 10 11 SATCOM 260 0750 MHz Sicral 1B SATCOM Lawrence 9 1A V 9 9M R 9 79AV Earthquakes Since lately we have felt a few earthquakes you have a number of internet links where you will find information on them and also other information http www phys um edu mt seismic University of Malta http www emsc csem org index php page home 2 European Mediterranean Seismogological Centre http openmap rm ingv it gmaps rec en Index htm Last earthquakes recorded bv INGV Network http Aside rm ingv it iside standard index jsp lang en THE ITALIAN SEISMIC BULLETIN http www gein noa gr services monthiv list html
3. in the IF chain will cause the phase of the signals to vary The computer programs implementing phase sensitive demodulation algorithms may find it difficult to handle these unwanted phase variations Fig 4 Typical screen shot of waterfall S meter readings will be meaningless for digital modes regardless whether AGC is used or not As explained the AGC feedback and the S meter indication is based on the average detected signals over the full audio passband and not the amplitude of individual narrow band digital signals Digital mode software designers have found another way to represent signal strengths by colour coding the waterfall displays fig 4 according to the amplitude of the different signals Conclusion General rules when working Digital Modes e AGC is neither necessary nor desirable and should be switched OFF e Saturation RF and AF may be avoided by appropriate use of the RF controls Robin 9H1ZZ Thanks to Robin 9H1ZZ for this article This space is blank due to the difference in text length between the Maltese and English versions 11 MARL Activities Membership Payment Whoever has still not paid his membership should do so if he wants to remain a MARL member The Financial Secretary is always ready to accept your membership fee whenever the MARL Centre is open or if you cannot come pay by cheque payable to MARL We remind you that the MARL Centre is open every Tuesday and Thursday between 6 00
4. only two pins they have the same dimensions like the others but the pins are hexagonal and not round but these plugs can be inserted in both wall plugs and also in wall plugs CEE 7 16 There are also plugs like Type J that are not very common that are rated at 16 Amps whose pins are square Equipment that takes more than 16 Amps must be permanently connected to the electrical system with branch circuit protection or by a high powered industrial connector This plug is used in these countries El Salvador Ethiopia Liechtenstein Madagascar Maldives Rwanda Switzerland Type K These are Danish three pin plugs Note that the earth pin is not exactly rounding These plugs are technically known as Danish 10 A 250 V unearthed which are the normal plugs in Denmark Danish wall sockets also accept type C and F equipment plugs Although equipment plugs Type E can also be inserted in these wall sockets they should not be used with earthed equipment A variation of this Danish plug known as DK 2 5a is for computer protection circuits from strong variations in supply voltage They can be inserted in Type K wall plugs but are designed in such a manner that normal Type K plugs cannot be inserted in the special computer type K sockets Previously Danish wall sockets used to have a switch so as not to allow the live connector to touch while the plug was being inserted or withdrawn Today sockets without switches are allowed but they are
5. p m and t 8 00 p m and Sunday between l 10 00 u and 12 00 Spring Show I remind MARL members that as in past years MARL is going to take part in the Spring Show at the San Anton Gardens on Saturday and Sunday 14 15 May 2011 While I encourage everyone to participate whoever wants to participate should inform the Secretary as soon as possible and advise him about your availability so that the Secretary can coordinate all the work Health and Safety Since as you know lately a lot of writings have appeared on newspapers on cell phones antennas and reasons of health and safety we are going to start giving you some information on precautions that everyone should take for his station to be according to international standards Thus everyone will be certain that he will not be exceeding international limits and the authorities will be able to certify that he is really working within international limits Therefore be attentive for information that we will give you later on Yahoo Group Be attentive and become members in the yahoo group to be fully informed with the latest activities that we intend to hold Do not forget that we may have activities which may not be able to appear on this magazine because it may have already been issued and therefore the notice will be sent on the yahoo group Send an e mail to Ivan 9H1PI ivan privitera at gmail com to become members in the group We remind you that whoever wants to can download th
6. Institute of Geodynamics National Observatory of Athens http www orfeus eu org Observatory and Recearch Facilities for European Seismology http earthquake usgs gov US Geological Survey http mednet rm ingv it Mediterranean Network http www iris edu hq Incorporated Research Institutions for Seismologv Lawrence 9 1A V OM R 9 79AV Internet webpages These are a few internet web pages that I have no doubt vou will find interesting because thev are connected with our hobbv http my integritynet com au purdic Electronic Projects http www morsex com building atoz htm Electronic Construction from A to Z http www tech systems labs com freesoftware htm Free Software http n4trb com AmateurRadio RCA_Ham_Tips rca_ham_tips htm RCA Ham tips http n4trb com AmateurRadio GE_HamNews ge_ham_news htm GE Ham News Lawrence 9HIAV 9H9OMHR H79AV Electrical plugs and sockets Today I am going to continue giving you more information on the different electrical plugs that you find in different countries around the world This plug has the earth pin offset to one side and the pins are not in a Straight line as one can see on the wall plug These are known as three pin Swiss plugs and were developed in Switzerland as plugs that must be used in Switzerland and are known as SEV 1011 Swiss 10 A 250 V The wall plug also accepts plugs J and C In Switzerland they also have other plugs that have
7. M SSB and slow CW e AGC should be set to F for fast while tuning and when working high speed CW or FSK e AGC should be switched OFF when working FM Since I work mostly Digital Modes I realised I needed to do more research on AGC in order to optimise my settings and be able to pull out the weak DX signals better The results of my detailed study were a bit surprising to me so I feel I could usefully share these findings with our members who might find them helpful Background In general there are three chains of amplification in receivers fig 1 RF radio frequency IF intermediate frequency and AF audio frequency RF Gain AF Gain Intermediate Frequency IF Fig 1 Three chains of amplification RF chain The sensitivity of the receiver varies according to frequency band Consequently pre amps and attenuators may be switched in out of circuit when bands are changed It is extremely important to avoid saturating the RF stages with strong out of band local broadcast stations so there are also RF band pass filters introduced automatically according to the band selected For the user it is common to allow control of the pre amps and attenuators and of course on the front panel there is always the variable RF gain control for finer adjustments The critical issue here is that the RF chain should amplify all in band signals linearly IF chain This is fixed frequency amplification where most of the re
8. ards have a dynamic range of around 100dB so there is no need for AGC However care is needed to ensure that the signal level never exceeds the maximum specified for the sound card Amongst other undesirable effects overloading the input a d converter will result in non linearity which shows up as inter modulation products multiple sidebands COMPUTER Monitor Screen Display Receiver Sound Card A D converter Digital Processing Unit Keyboard AF output Fig 3 Connection for processing digital modes by computer If AGC is active it is based on the detected signal averaged over the audio bandwidth of the detector In most ham transceivers this is normally about 2500Hz However recent developments include DSP digital signal processing in the IF chain to adjust the frequency response for different situations which may result in narrower variable IF bandwidths 10 Many digital modes have bandwidths of just a few Hz so there could be a number of different signals present within the audio passband Several digital modes may even be superimposed With the AGC operating all the signals in the passband will be affected So if there are a few or even just one very strong signals the AGC will lower the overall gain and any weaker signals within the passband may disappear Some digital modes rely on phase modulation As already mentioned when considering FM frequency modulation continuously altering the feedback
9. ceiver s gain is obtained as well as providing narrow band selectivity For various reasons the chain may be implemented as several stages each with different fixed frequencies In modern transceivers the user is given some control for selectivity and interference suppression The AGC circuitry varies the gain of the IF chain depending on the AGC settings AF chain Usually the AF gain is set by the user so that the audio output is at a convenient level for listening However the characteristics of the other amplification chains are critical when searching for weak signals in the presence of noise The AGC works to bring the detected signals and noise to an appropriate level for the input to the audio amplifier Further tailoring of the AF chain s characteristics assists in enhancing the wanted signals As noted already the AGC acts on the IF amplifier chain as indicated in Fig 2 Signals are detected at the output of the IF chain and feedback applied varying the gain of the amplifiers to bring the signals to a preset level These parameters cannot be altered directly by the user IF Signal Amplifier Chain Detector Set AGC response time Fig 2 AGC feedback diagram The AGC circuitry features fast attack slow release In practice it is usual for the AGC circuit to respond in less than 0 1 second and the user chooses a release time up to several seconds Depending on the characteristics of the received signals the AGC relea
10. e Magazine from www 9hImrl org newsletter htm Lawrence SHIA V OM R 9 79AV 12
11. e first one is smaller and has a round hole in the middle and two 8 shaped holes above and below These accept both Type L equipment plugs as well as Type C Euro plugs The second socket is similar to Type F but has a hole in the centre It accepts equipment plugs Type E F C and L of 10 Amp rating but also twice the size of a normal Type L socket Sometimes these sockets also have extra holes to accept Type L 16 plugs This plug is used in the following countries Chile Cuba El Salvador Ethiopia Italy Libya Maldives Syria Tunisia Uruguay Tip M These plugs are used in South Africa have three round pins like Type D but larger They are technically known as BS 546 South African 15 A 250 V and are the plugs used in South Africa e 9 e This plug is used in the following countries Hong Kong Mozambique South Africa Swaziland Lawrence 9 1A V 9HIMHR H79AV SHIVW 9HIGB AGC Automatic Gain Control Which settings to use Thanks to Robin 9H1ZZ for the following interesting Article on AGC The AGC controls in most communications receivers are readily accessible for the operator Ham transceivers allow for this also but rarely does the user s manual provide much guidance on the choice of settings or on the impact of using inappropriate values I have looked at some Kenwood ICOM and Yaesu manuals and extracted the following consolidated advice e AGC should be set to S for slow when working A
12. icense conditions the authorities have a right to come and inspect our stations measure the signal strengths and see what they consider suitable to protect health and that regulations are observed Here I appeal to everyone not to use the yahoo group to alarm the people uselessly or create misunderstandings between the Committee and the members because that is what happens when one just writes without thinking on this group Fools rush in where Angels fear to tread As always I hope that you find the information in the magazine useful to you and if you have some article please leave it in my QSL box or you can send it to me on my e mail Lawrence 9HIAV 9H9OMHR H79AV Spring Show I remind MARL members that as in past years MARL is going to take part in the Spring Show at the San Anton Gardens on Saturday and Sunday 14 15 May 2011 Whoever wants to participate should inform the Secretary as soon as possible and advise him about your availability so that the Secretary can coordinate all the work This is an opportunity for one to participate to continue showing our hobby to the public as well as for together with the family to be able to see and enjoy the show which was always good and beautiful and at the same time will be able to enjoy his her hobby Lawrence 9HIAV 9H9OMHR H79AV Frequencies in the Libyan issue These are the latest frequencies that are being used in the Libyan issue 4169 0 kHz NATO Net Some voice and Link 11
13. required to have a cavity to prevent the pins from touching However their shape rarely allows the pins to touch However sockets in new installations in Denmark are required to have an earth connection Old installations do not have this requirement but must be protected by RCD GFCI HFI in Danish From 2008 French sockets type E were allowed to be installed in Denmark but not Type E This plug is used in the following countries Bangladesh Denmark Faeroe Islands Greenland Guinea Madagascar Maldives St Vincent Senegal Tunisia Type L These plugs are Italian and have three pins in a straight line with the centre pin connected to earth These plugs are not polarized and can be inserted in either direction and are the type of plugs one finds installed in Italy They are technically known as CEI 23 16 VII There are two models rated at 10 Amps and 16 Amps differing in both contacts diameter and spacing In older installations an adapter may be required The 10 Amp plug is similar to CEE 7 16 but has an earth pin and thus wall sockets CEI 23 16 VII accept Euro plugs The 16 Amp plugs have thicker pins which are a little further apart The 16 Amp plugs are sometimes called northern European or Industrial but this is not correct While it is possible to insert plugs Type D and E in L wall sockets you can damage the wall plug and they may become stuck There are also two other Type L plugs that are much used in Italy Th
14. se will be more or less effective The summary at the beginning of this article shows at which settings the transceiver manufacturers believe their equipment works best Effects of AGC S meter Although the user cannot vary the gain the amount of feedback the AGC applies is presented to the operator as an indication on the S meter So the stronger the incoming signal the more 9 feedback is applied and the higher the S meter reading This also explains why the S meter changes when the RF gain control is varied since the AGC attempts to keep the detected signal level constant Notice also that if the AGC is switched OFF there is no feedback and the S meter reading no longer represents the received signal strength FM Now it is a fact that varying the feedback will not only alter the gain but also influence the phase shift through the amplifier chain So normally as the detected signal changes in amplitude AGC will be applied varying both the gain and the inherent phase shift continuously This could cause potential problems to FM discriminators so for FM signals the AGC is automatically disabled Digital Modes Modern transceivers have a rear panel connector specifically for users to access the detected signals prior to the AF amplification chain Digital modes use this facility The detected output is digitized directly using the computer s sound card for audio frequency processing by computer as shown in Fig 3 Sound c
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