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February 2010
In this issue:
Club News
Future Meetings and Events
AGM and Construction Contest
Members News
Computer Corner
Technical Snippetts
Noticeboard - Wanted & For Sale
News from other Clubs
AGM Agenda
05 Feb 10
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M
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Annual General Meeting
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28 Feb 10
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R
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Rainham Radio Rally
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07 Feb 10
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R
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25th Canvey Radio & Electronics Rally
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05 Mar 10
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M
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A History of Power Supplies part II.
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14 Feb 10
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R
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Harwell Radio and Computing Rally
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18 Apr 10
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R
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West London Radio & Electronics Show
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E = External event, M = club meeting, R = Rally
Recent Event News
8th January 2010 * - Club Discussion followed by "A History of Power Supplies" part II.
Due to the bad weather conditions this meeting was cancelled at the last minute which was just as well as the meeting room toilets and water pipes were frozen solid. We hope for better weather in February for the AGM.
The Club Discussion will take place at the February meeting before the AGM and the talk on Power Supplies has been rescheduled for the March meeting.
Future Club Meetings and Events
5th February 2010 - Annual General Meeting
This meeting will be divided into two parts - the Club Discussion held over from January followed by the formal AGM.
I wrote to members in January this year outlining the issues that the club faces. The Club Discussion will review these together with members' thoughts and ideas and outline what needs to done to address them. We have reached the point where doing nothing is no longer an option.
Victor G1PKS will be standing down from his post as Secretary at the AGM so a replacement will be required if we are to continue.
An agenda for this meeting, Officers reports and a very short survey inclusing an SAE will be posted to all club members with this newsletter. Please complete the survey and post it back to Victor by return so that we can assess the results prior to the AGM.
05 March 2010 - A History of Power Supplies part II
The much delayed second part will be presented at the March meeting. Previous attempts have been thwarted by pressure of time and bad weather so let's hope that this time we are successful.
14-16 May 2010 Dayton Hamfest
Since 1952 Hamvention® has been sponsored by Dayton Amateur Radio Association (DARA). For many years it has been the world's largest amateur radio gathering, attracting hams from throughout the globe. This year the theme is "Amateur Radio Clubs Worldwide: The Lifeline".
Activities include:
 Forums where you can meet and hear authorities on all facets of amateur radio.
 500 inside exhibit spaces where the exhibitors are showing their latest equipment and are available to answer questions about their products
 A HUGE 2500+ space Flea Market area! The largest of its kind!
A visit to this event is the opportunity of a lifetime.
Members News
Giorgio, our member in Italy, send his greetings and best wishes to all members together with his apologies for not being able to attend the AGM.
Technical Snippets
a) The benefits of CW over SSB in poor or low power conditions are very well known. The much narrower bandwidth of the CW transmission allows the receiver to use a smaller bandwidth and the operator's brain can concentrate on pulling the signal out of the noise and decoding it.
The latest data transmission modes, WSJT and WSPR and are pushing this principle even further. WSPR (weak signal propagation reporter), a computer based beacon mode, uses a transmission bandwidth of just 6Hz and one UK operator has achieved a range in excess of 1000Km on 500KHz with an ERP of around 1 milliwatt. His transmitter is capable of 10W plus output but the aerial efficiency is extremely poor with most of the transmitter output being dissipated in the earth loss resistance instead of being radiated. The downside of this mode is the high stability requirements for the transmitter frequency.
MAP65 implements a wideband, polarization-matching receiver for JT65 signals. It works together with Linrad (by SM5BSZ) and dual-polarization RF hardware to receive and decode all detectable JT65 signals in a 90 kHz passband, matching the linear polarization angle of each one and producing a band map of decoded callsigns sorted by frequency. Its principal application is EME (Earth - Moon - Earth or moon-bounce) on the VHF and UHF bands.
Software for these mode is available on the Internet for both Windows and Linux.
b) Your scribe has been constructing a three band valve transverter for use with his Heathkit SB-101 transceiver. So far, the 50MHz transmitter section is working and delivering some 20W of output power from a drive level of 20 mW on the 28-30MHz band and the receiver section is waiting for the RF stage to be completed. The application of 50+ year old technology has required some research on the Internet and a number of revisions to the circuitry resulting initially in very messy wiring which has now been tidied up. Once the first section has been completed, the layout will be copied for the other two sections (70 and 144MHz).
c) AMSAT Satellite AO-51
AMSAT-NA VP Operations, Drew KO4MA says AO-51 will be back in to it's normal configuration between January 4 - January 31.
FM Repeater, V/U
Uplink: 145.920 MHz FM
Downlink: 435.300 MHz FM (570 mw)
9k6 BBS and Telemetry
Uplink: 1268.700 MHz FM
Downlink: 435.150 MHz FM (450 mw)
The Operations Team repolarised the magnet on AO-51 to again favor the northern hemisphere on January 9. There may be some rapid fading as the nutation dampers do their job over the next few weeks. The Operations Team appreciates all the reports and observations during this experiment. Telemetry collection continues, and anyone interested can access the telemetry data in the AO-51 archive. [Source - AMSAT]
d) Power Supplies
One of the topics that the Power Supply talk in March will cover is that of power factor correction.
The power factor of an AC electric power system is defined as the ratio of the real power flowing to the load to the apparent power and is a number between 0 and 1. Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power can be greater than the real power.
At one time, this was only thought critical in large industrial installations but with the massive increase in use of switching power supplies like "wall warts" and personal computers the problem is much more extensive.
Thankfully, there are a variety of passive or active electronic solutions. Passive correction involves removing the harmonic content that results from poor power factor units using some form of filter which can be bulky with high current operation. Active correction takes the form of specialised ICs and their associated components that can provide the required correction factor in typical consumer power supplies.
Power companies may charge large industrial site with a poor power factor so it is in their interests to correct the problem.
Computer Corner
I have been experiencing Windows 7 Professional (64 bit version) for the first time having just taken delivery of a new 64 bit computer. Most 32bit software installs and runs with no problems although the issue of permissions is much more critical than with previous versions of Windows.
The processor is an AMD Phenom II Quad Core with over 900 pins on the underside and a six inch high heatsink on top to keep it cool. Other ICs on the motherboard use heat-pipe technology for cooling. Clock speed is 2.8GHz, Front Side Bus runs at 1.066GHz and it has 4GB of memory and 1TB (1000GB) of hard drive space. RF interference from this new PC has yet to be evaluated but the ASUS motherboard has spread spectrum options (not yet tested) for the processor and memory in case some of the clock frequencies generate interference on critical frequencies.
The vast amount of processing power offered by current day processors is required for complex operating systems like Windows and Linux which can have fifty or more processes running in the background to support whatever application is currently being used. This new PC powers up in 16 - 20 seconds from a cold start to a stable Windows desktop.
Another benefit of modern processors and operating systems is virtualisation which allows you to create and run virtual operating systems under an existing operating system. Put more simply, while running Windows 7 you can create a separate environment in which you can install and run an earlier copy of Windows (back to Windows 98) or even MS-DOS. Microsoft provides Virtual PC 2007 in the form of a free download from their web site.
Miscellaneous
HF Contests:
29/31 Jan - CQ 160m Contest (CW)
20/21 Feb - ARRL Dx Contest (CW)
6/7 March - ARRL Dx Contest (Phone)
27/28 Mar - CQ WPX Contest (SSB)
29/30 May - CQ WPX Contest (CW)
The RSGB have advised that from 1800UTC on 22nd January 2010 the HF frequencies used to respond to the immediate needs of the Haiti Earthquake, 14.300MHz, 14.265MHz , 7.045MHz, 7.065MHz, 7.265MHz, 3.720MHz and 3.977MHz will return to normal use. [RSGB]
Meeting Rooms: I have been advised by the Parish Rooms manager that a much overdue program of renovation has commenced. The roof and exterior wall repairs have already been completed and a new floor laid in the main room. The remaining rooms and entrance hall will be completed in the coming weeks.
Notice Board - Wanted and For Sale
The Notice Board is for all club members to use so if you have one or more items that you wish to buy or sell then please send in the details. The current list of items may be viewed at: http://www.g3oou.co.uk/ in the "Notice Board - Wanted and For Sale" section.
Wanted:
SWL club member looking for a VHF multimode receiver covering at least 144-146MHz. Contact Victor on 020 8653 2946 or Bob on 01737 552170.
For Sale:
Ken G3DJK has a PCI Firewire Card 1349A, Maplin Code A49HH (new and unused). Best offer secures. Contact Ken on 020 8679 2717
Sycom run by Robin G3NFV supplies a range of electronic components & new/second hand equipment. The web site can be found at: http://www.sycomcomp.co.uk/
JAB Electronic Components, PO Box 5774, Birmingham, B44 8PJ supply a wide range of electronic components and can be contacted on 0121-682-7045 or by email at: jabdog@blueyonder.co.uk
73
 G3OOU
Diary of External Events
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7 Feb - 25th Canvey Radio & Electronics Rally
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'The Paddocks', Long Road, Canvey Island, Essex SS8 0JA (southern end of A130). Opens 10.30, £2. Contact Dave, G4UVJ, on 01268 697978 (evenings) or visit website: www.southessex.ars.btinternet.co.uk
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14 Feb - Harwell Radio and Computing Rally
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Didcot Leisure Centre, Mereland Road, Didcot OX118AY. TI S22 (V44), free CP, £2 (u12 free), Opens 10:15/10:30, Special Interest Groups. Details on 01235 816379 or email ann.stevens@btinternet.com. Web site www.g3pia.org.uk
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28 Feb - Rainham Radio Rally
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Rainham School for Girls, Derwent Way, Rainham, Gillingham, Kent ME8 0BX. Trevor, G6YLW, 0771 7678 795 0771 7678 795
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18 Apr - West London Radio & Electronics Show
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Kempton Park Racecourse, Staines Road East, Sunbury on Thames, Middlesex TW16 5AQ. Talk in. Opens 9.50/10.00, Lecture stream. Details from Paul, M0CJX, 0845 165 0351, info@radiofairs.co.uk or visit the website at: www.radiofairs.co.uk
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14-16 May 2010 Dayton Hamfest
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Forums, exhibition space and a huge flea 2,500 space market, talk-in, live video and sound broadcasting over the Internet. More information from http://www.hamvention.org/index.php
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News from other Clubs
Club Secretaries - please send your meeting programs to Bob G3OOU. Our newsletter is now published during the third week of each month and closes for editorial input at the end of the second week. Due to differing publication dates and short lead times it is sometimes difficult to include other clubs' specific events although we will endeavour to do so if advised in time.
Chelmsford Amateur Rado Society (CARS)
Secretary Martyn Medcalf G1EFL Tel: 01245-469008. First Tuesday of each month at MASC, Beehive Lane, Great Baddow, Chelmsford, CM2 9RX. Essex. UK. Web: www.g0mwt.org.uk
02 Feb
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"The LFA (Loop-fed Array) Yagi" by Justin Johnson, G0KSC.
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24 Apr
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CARS "On the Air" - International Marconi Day at Sandford Mill, 10am to 5pm.
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Coulsdon (CATS) 2nd Monday every month, 8pm at St Swithun's Church Hall, Grovelands Road, Purley. Contact: Andy Jackson G8JAC, 020 8651 2727, G8JAC@btinternet.com
08 Feb
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`How to lose your SMD Virginity' by Terry, G4CDY
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08 Mar
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Video/film evening (provisional)
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12 Apr
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TBA
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Echelford Amateur Radio Society
Meets on 2nd and 4th Thursday of each month.
Phone for details.
Mitcham & District Amateur Radio Society
Secretary: Mike Knott G0WCR, 76 New Barnes Avenue, Mitcham, Surrey, CR4 1LF.
Tel: 020 8764 4716
Phone for details
Reigate Amateur Transmitting Society
Secretary: Tim Trew G8JXV
Meeting on 3rd Thursday of each month, 7:30pm at RNIB Redhill College, Philanthrophic Road, Redhill
Surrey Radio Contact Club (SRCC) 1st and 3rd Monday every month, 8pm at Trinity School, South Croydon. Contact: Ray Howells G4FFY on 020 8644 7589 or secretary@g3src.org.uk for more details.
01 Feb
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SMD Masterclass with Gareth G4XAT
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01 Mar
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Spring Surplus Equipment Sale
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12 Apr
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AGM
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10 May
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Project Constructing Project Evening
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Sutton & Cheam RS. 3rd Thursday every month, 8pm at Sutton United FC, The Borough Sports Ground, Gander Green Lane, Sutton. Contact John Puttock G0BWV on 020 8644 9945
18 Feb
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'An Introduction to Military Communications' by Mike O'Beirne G8MOB
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18 Mar
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'Operating Digital Modes on HF' by Evan Duffield MØTJU
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15 Apr
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'Kite & Balloon Supported Antennas' by Roger Stafford - G4ROJ
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20 May
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Annual General Meeting
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Wimbledon. 2nd and last Friday every month, 8pm at Martin Way Methodist Church, Buckleigh Avenue, Merton Park, SW19 9JZ
Contact Jim Bell, M0CON on 020 8874 7456
26 Feb
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Amateur TV by John Stockley G8MNY
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26 Mar
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Commercial Satellite Communications by Peter Beardow G1SHV
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09 Apr
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Surplus Equipment Sale
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14 May
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Direction Finding Hunt
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28 May
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Vintage Rig Evening
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