February 2012
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
Meeting and Event Diary:
03 Feb 12
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M
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AGM and Construction Contest
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02 Mar 12
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M
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TBA
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E = External event, M = club meeting, R = Rally, T = Training course
Dear Reader
Recent Event News
6th January 2012 - Loops by Colin M0XED
Colin presented an illustrated talk about small transmitting loops, covering the basic principles, small loop equations, efficiency, radiation pattern, nulls, design considerations, performance comparison and the installation and operation of the WIMO Baby Loop for 40m - 10m.
Loops present an extremely low impedance if fed directly - typically in the region of 0.005 ohms so a matching facility is definitely required for a standard 50ohm feeder. This can be a simple tap away from the feed point or a coupling loop in the same plane as the main loop - the former causes a slight asymmetry in the radiation pattern.
One of the benefits of a loop is the presence of a very narrow null in the plane broadside to the loop (exactly the opposite to a dipole) whereas the wanted response is fairly broad. This allows strong interfering signals to be reduced in strength by careful positioning of the loop.
Colin also explained that as the current in the loop and the voltage across the tuning capacitor were both proportional to the resonant Q they could be extremely high. An example was quoted for a 100W output transmitter with a loop current of 31 amps and a capacitor voltage of around 3Kv. At these current levels the size and quality of the loop metal is extremely important. The WIMO loop is approximately 1m in diameter and made of 50mm diameter aluminium tubing. A small improvement in surface resistivity could be obtained using silver plated copper instead of aluminium but this would raise issues of weather proofing so the aluminium is a good compromise.
A side effect of the high Q is the resulting narrow bandwidth. A well made loop tuned to 1.84MHz should have a Q of between 800 and 1200 so the bandwidth would be between 2.3KHz and 1.53KHz respectively - fine for CW but not for SSB.
Colin uses a baby WIMO loop covering 7 - 30MHz with remote controlled motor tuning and mounted on a remotely controlled rotator. Best dx to date is Ulan Bator and the USA. The aerial costs about 1200 Euros from an Italian supplier and is ideal for locations lacking space for more conventional HF aerials.
A number of theoretical questions were raised and Colin has promised to do some more research and report back in a future newsletter.
Future Club Meetings and Events
3rd February 2012 AGM and Construction Contest
The next meeting will be our Annual General Meeting and Construction Contest where members have the opportunity to elect the officers and committee for 2102, have their say about past and future meetings and activities, decide what they can do to help the club and offer an entry in the construction contest for which an award is made to the winner.
Officers reports will be presented during the meeting for which an agenda has been provided at the end of this newsletter - please bring it with you to the meeting.
Club annual awards from last year's AGM should be returned by the February 2012 meeting please (M6RUF and M0XED).
Foundation Training Course
Our planned Foundation Course for Autumn 2011 had to be cancelled because the drop-out rate made the eventual numbers uneconomic. Although we have subsequently had some additional enquiries the total numbers are still less than ideal. If you know anyone that would like to take part please ask them to email or contact a committee member.
Miscellaneous
a) Science Museum & Imax cinema
If you have not been to this museum it is well worth a visit. The museum covers five floors so there is a vast amount to see with topics including the development of the space race, telecommunications, the history of the Earth and many many more. There is a restaurant and shop on site. Entry to the museum is free but there is a charge for entry to the cinema.
The Imax cinema is showing a series of 3D films including one about repairs to the Hubble Telescope and some breath taking colour shots of far galaxies.
b) Planets
A recent article in the Times discussed the findings of scientists that Earth is no longer considered to be unique in the universe. Over the last ten years some 700 earth like planets have been discovered which leads to the conclusion that there are probably billions spread across the universe. [Source: The Times 12 Jan 2012 - Ed]
Technical Snippetts
a) Coaxial cables: Users of coaxial cables will be aware that the low loss variety are often so stiff that they cannot be used for rotateable aerials. One possible solution to this problem is to consider RG8X which is a smaller and more flexible version of UR67.
However, it has one minor disadvantage in that it will not fit a standard BNC plug although a special version BNC plug is available.
UR67 (similar to RG213), 50ohms, 10.3mm OD, 0.66dB per 10m at 100MHz, 2.52dB per 10m at 1000MHz, not very flexible
RG8X coax cable, 50ohms, 0.24" OD, 4.5dB loss per 100' at 146MHz, max power 350W at 30MHz, 150W at 150MHz, requires a special BNC connector compared to RG58. Much more flexible than UR67.
b) Diagram Designer
This is a useful and free piece of Windows software by Meesoft for drawing a number of different types of diagram including electronic circuits. Completed diagrams can be copied to the clipboard where they are automatically converted to a Windows Metafile format which can be imported in a wordprocessor or desk top publisher as a scalable image.
The package comes with a series of predesigned templates. For more information see:
c) SB-101 Refurbishment
Your scribe has been busy refurbishing a Heathkit SB-101 HF band transceiver which was originally sold as a kit in the mid 60s. A lot of the work has been in correcting problems of ageing, mainly the solid carbon or carbon composition resistors which have mostly aged high, sometimes as much as 50%. A few capacitors have been replaced, some valveholders tightened up and the rig is now receiving and transmitting on all bands including a new band covering 1.8-2.0MHz which Heathkit never provided on the valved SB-Line.
The minimum discernable signal on receive is 0.1uV and the transmitter produces 100W on all bands except 10m where it is 90W. The original designers probably never thought that their products would last so long.
d) Thermionic Valves - Those readers interested in the manuafacture of valves might like to visit the following two excellent but very different web sites. The first is about the Mullard high volume manufacturing factory at Blackburn and the second is about Claude Paillard who makes small quantities of bright emitter valves and shows their use in a simple radio receiver.
e) An Interesting Web Site:
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:
Tronix-1 13V PSU £10
GEC SWR-9 SWR meter (new) £10. Contact Victor G1PKS on 020 8653 2946
Component Suppliers
Barend Hendriksen in Holland carry a wide range of interesting electronic components at reasonable prices and provide a good service with deliveries to the UK taking only a few days. They can be found at http://www.barendh.com/
73
G3OOU
Diary of External Events
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5 Feb - 27th Canvey Radio & Electronics Rally
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'The Paddocks', Long Road, Canvey Island, Essex SS8 0JA (southern end of A130). Free CP, OT 10.30, C, DF, TS. Dave, G4UVJ, 01268 697 978 (evenings).
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12 Feb - Harwell Radio & Electronics Rally
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Didcot Leisure Centre, Mereland Road, Didcot. Talk In V44 (S22), Opens 10:00/10.30, entry £2.50 (under 12 free). Contact Ann, G8NVI, 01235 816 379, ann.stevens@btinternet.com
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04 Mar - Cambridge & District Amateur Radio Club Rally
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Wood Green Animal Shelter, King's Bush Farm, A1198 London Road, Godmanchester, Cambs PE29 2NH. Opens 10:00, Entry £3, Talk In S22, Contact John, G0GKP, 01954 200 072, j.bonner@ntlworld.com.
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11 Mar - Bournemouth Radio Society 24th Annual Sale.
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Kinson Community Centre, Pelhams Park, Millhams Road, Kinson, Bournemouth BH10 7LH. Opens 09.30, admission £1.50, Contact John, G0HAT, 07719 700 771
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15 Apr - West London Radio & Electronics Fair
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Kempton Park Racecourse, Staines Road East, Sunbury on Thames, Middlesex, TW16 5AQ. Opens 7:30 for traders, 10:00 for visitors.
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15 Apr - Cambridgeshire Repeater Group Rally
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Foxton Village Hall, Hardman Road, Foxton, Cambridge CB22 6RN. Opens 10:00 for visitors, 7am for traders, entry £2, Talk In S22, Contact Lawrence, M0LCM, 01223 711 840, rally2012@cambridgerepeaters.net.
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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
07 Feb
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"Either Enigma or a simple Transceiver project".
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03 Apr
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"Titanic Evening"
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05 Jun
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"Marconi - History - Opening of the Worlds first Wireless Factory in New Street, Chelmsford 100 years ago"
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Coulsdon (CATS) 2nd Monday every month, 8pm at St Swithun's Church Hall, Grovelands Road, Purley. Contact: Steve Beal G3WZK on 01883 620730 or secretary(at)catsradio.org
13 Feb
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Contest Logging by G0KZT
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12 Mar
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WSPR by Walter Blanchard G3JKV
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Dorking & District Radio Society
Meetings at the Friends' Meeting House, Butterhill, South Street, Dorking RH4 2LE starting at 7.45pm.
28 Feb
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- Early TV Receivers - Stephen Niechcial.
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27 Mar
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Valve Audio Amplifiers - aspects of their design and performance - Keith Thrower.
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24 Apr
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Radio from VP8 - Roger Eeles - G0SWC / VP8DBR
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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
Tel: 01293 775278. Email:
Meeting on 3rd Thursday of each month, 7:30pm at RNIB Redhill College, Philanthrophic Road, Redhill.
South East Essex Amateur Radio Society (SEARS) ContactDave G4UVJ on: 01268 697978,
Meetings: 8pm 2nd Weds each month at: 31 Feeches Road,Southend on Sea SS2 6TE (temporary location which may change for each meeting - please see web site).
05 Feb
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Canvey Radio Rally .Paddocks, Canvey Island, SS8 0JA
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14 Mar
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Talk by Dave G4AJY "Frequency, Wavelength and Waveform."
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11 Apr
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Radio Practical operating and Rally report
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09 May
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Talk by Mike M6KEB on Aircraft servicing
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Surrey Radio Contact Club (SRCC)
1st. and 3rd. Mondays every Month (unless Bank Holidays) 7.30 for 7.45pm at Trinity School, Shirley Park, Croydon, CR9 7AT. Contact John Kennedy G3MCX on 020 8688 3322 or
06 Feb
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Club Talk
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05 Mar
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Spring surplus sale
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02 Apr
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AGM
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14 May
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Construction 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 or email info(at)scrs.org.uk Web: http://scrs.org.uk/
16 Feb
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`Heathkit Refurbishment and Home Construction Techniques" by Bob G3OOU
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15 Mar
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To be confirmed
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24 May
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AGM
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Wimbledon. 2nd and last Friday every month, 8pm at Martin Way Methodist Church, Buckleigh Avenue, Merton Park, SW19 9JZ
Contact: Andrew G4ADM on 020 8335 3434 or andrew.maish(at)ntlworld.com
27 Jan
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RF Phenomena: Demonstration and Talk by Andrew G4ADM
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10 Feb
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Update on Bletchley Park and the Computer Museum by Len
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24 Feb
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On the Air
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Please replace the (at) with @ in all email addresses shown in this newsletter.
Items For Sale
Sensible offers are invited to Bob G3OOU for the following items that are for sale from three radio shacks:
Description
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Price
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Description
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Price
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2 two-way data transfer switch box - useful painted project box
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£2
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1 bag of pre-packed ICs, 1 bag of RS Components prepacked, 1 bag of identified ICs and transistors
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£5
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3 way data transfer switch box - useful painted project box
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£2
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Original HRO receiver printed manual with an S Meter conversion article.
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£5
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2 x 15W soldering iron, mains powered
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£1
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A Future Electronics transistor tester FTC 401
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£5 the lot
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1 Box of various coax and general purpose sockets & plugs
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50p per connector
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Description
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Price
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Description
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Price
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Bosch mobile radio with fist mic - amateur band frequencies not yet established
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£20
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Raymart HF bands Wavemeter
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£4
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Nova mobile radio
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£10
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Mains Bench PSU with 12V output
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£10
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Icom IC-240, 144-146MHz, 1 & 10W FM, synthesised transceiver. Internal diode matrix channel programming panel.
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£30
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Crystal calibrator on a PCB with 1MHz HC6/U crystal and some TTL ICs
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£2
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FT290 + manual. 144MHz, 0.5W/2.5W, multimode transceiver
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£50
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Description
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Price
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Description
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Price
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Marconi TF2437 100MHz counter timer
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£50
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Box of assorted valves including one 6SA7
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£1 each
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Datong D70 battery powered Morse tutor
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£25
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Box of assorted variable capacitors
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£3 each
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Ex Army Morse key
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£5
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All items are bought as seen and sold on a first come first served basis.
Agenda for 2012 Annual General Meeting
Date: Friday 3rd February 2012 at 8.00pm
Venue: All Saints Parish Church, Beulah Hill, Upper Norwood, London,
SE19 3LG
Agenda:
1. Apologies for Absence
2. Minutes of 2011 AGM
3. Matters arising
4. Chairman's Report (G8NKM)
5. Secretary's Report (G3OOU)
6. Treasurer's Report (M0XED)
7. Election of Officers and Committee members for 2012
8. Appointment of an Auditor for 2012
9. Annual and Meeting Subscriptions following a rent increase
10. Club programme for 2012
a) Membership drive, publicity etc.
b) Meetings
c) Field events
d) Any other items
11. Any Other Business
a) Members discussion
12. Presentation of Annual and Construction Contest Awards
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CRYSTAL PALACE RADIO AND ELECTRONICS CLUB
Membership renewals are now due for 2012.
If you have not already done so, please send a cheque for £12.00 made out to
Crystal Palace Radio and Electronics Club to Colin Butcher M0XED with this form.
Name______________________________________Callsign_______
Address __________________________________________________
____________________________________Postcode_____________
Phone no_________________________
Email ____________________________
I will / will not * be attending the AGM on 3rd February 2012.
* Delete as appropriate