Chelmsford Amateur Radio Society

Past Club Meetings:   July to September 2009

by Murray Niman, G6JYB & Clive Ward, G1EUC.

D-Star Range
                      D-Star Range of Rigs
"D-Star"?   What is this D-Star?

Murray explained it is the latest Amateur Radio communications mode.

Although relatively new, D-Star (a new Digital Voice/Data mode) is proving popular with over 50 systems licensed so far in the UK 2m/70cm bands, including a number replacing FM repeaters; and many new radios being sold with the mode built in.

Many of these new systems can be linked via the internet so it is possible for example to call a specific Radio Amateur elsewhere on the planet or see others moving on a map (as GPS can be integrated).

This new technology for Radio Amateurs has firm roots in Essex in the form of GB7ZP in Danbury and GB7SS at Hockley.

Clive, G1EUC provided a live demo on the night with a contact with Mike G4ZPE (Zipy).

UK Systems:

We were fortunate to have two D-Star experts to tell and show us this new communication mode.

Thanks to Chris, G0IPU for providing the 70cm Aerial and cable to the tripod in the field behind MASC.

CARS had its famous Raffle with at least 10 prizes.
With the agreement of HM Government and an Essex Charity we were able to give away a 11 and a 14Watt Economy Light Bulb manufactured by Osram to all who had booked in - FREE.

August Meeting - "Where do our Wavelengths come from?!
By Peter Chadwick, G3RZP.

Peter is a well known IARU Consultant, senior contributor in International circles and was ex-Marconi and a past CARS President of the RSGB (1993).

Peter Chadwick Meeting
Peter's presentation drew a good audience including some from local Amateur Radio Clubs.

Peter Chadwick Meeting Peter Chadwick Meeting
Row above Tony, G4YTG are Peter's visitors from 40 years ago.

Chairman John welcomed Barry Tew, G3WFF (red shirt, above), Jon Naunton, G8CYI from Tollesbury and Dave Ponting, (ex G8CVM) from Maldon.   The group used to meet with Peter 40 years ago, getting Fish & Chips in Willie McClintock’s, G3VPK (another CARS Past RSGB President) minivan after a CARS Meeting (which was in Arbour Lane, Chelmsford in those days).
Brian Miller, M1HHL, Chairman of the Radio Society in Hereford was also welcomed.

Peter Chadwick Meeting
Lottery purchased Digital Projector showing Peter's slides from a Dongle on the new CARS Lottery Computer.
Peter came to Chelmsford by train, hence he was using all CARS visual equipment.

In his talk Peter described how the Bands we take for granted today were not gifted to us by good fortune.   In the early days of telegraphy and wireless there were no standards, allocations or band-plans and chaos soon ensued.   This led to the formation of the Internal Telegraphy Union (ITU) in 1865 which later took on Wireless in 1896, later renaming itself to the International Telecommunication Union as we know it today.

The IARU which represents Amateurs at this level was formed in 1925 at the initiative of Hiram Maxim W1AW of ARRL and is based on reps and subs from its member National societies.   This was fortunately just in time ahead of the 1927 ITU Conference where RSGB could not get any input to the UK delegation.   Fortunately because of the IARU work Amateur Bands were allocated Internationally at:-

1715 – 2000kHz
3500 – 4000kHz
7000 – 7300kHz
14000 – 14400kHz
28000 – 30000kHz
56000 – 60000kHz

At the next conference in 1932 the ‘Amateur Service’ was formally recognised – the only hobby to have formal recognition in international law.   By 1938 IARU was able to field a strong presence of observers and able to limit military demands in Europe, we lost ~3.6MHz and 7.2-7.3MHz – though this proved academic as the new rules were due to come in on Sept 1st 1939

After the War the ITU became a UN agency and held its landmark conference in 1947 in Atlantic City.   The RSGB had to fight hard to prevent the Post Office reducing 40 and 80m and total loss of Top Band.   In the end 7.2-7.3 was lost as was 112MHz, which was replaced by 21MHz and a new worldwide 144-146MHz 2m band.

In more recent times, the threats have continued and increased but hard work by IARU volunteers has resulted in:-

WRC-79: 10, 18, 24MHZ HF Bands
WRC-03: Removal of Compulsory Morse
Restoration of 7.1-7.2MHz in Region-1
WRC07: 135kHz

The next conference in Feb-2012 will discuss IARU’s request for a band around 500kHz as well as new radar allocations which might threaten HF and VHF.

So far there has been no success in getting 5MHz onto the agenda or harmonising the 50MHz band.   Each ITU conference sets the agenda for its successor and it is notoriously difficult to win a slot in the horse-trading that occurs for the future Agenda Items.

IARU via its three regional groupings are the originators of the Bandplans, maintain an Intruder Watch Service (IARU-MS) in Primary Bands (eg for iffy frequency use by HF broadcasters or Spanish Trawlers etc) and undertake training in Developing Countries.

IARU Consultants and reps do their best to also feed info into various key ITU, CEPT etc committees in order to influence policy and technical recommendations.

The talk underlined the fact that Radio Spectrum is a scarce and highly valuable economic resource.   Subject o many pressures.   Our frequencies need to be defended at National and International level and the IARU do this for amateurs worldwide.

So as Peter pointed out, the answer to the question, ‘Where do our wavelengths come from?’ or rather ‘Who defends our Wavelengths?’ is that it is IARU and its member Societies such as RSGB – and remember that ‘Without Wavelengths, there is no Amateur Radio’

After the talk Peter’s extensive knowledge was tapped by many questions from the audience on both IARU and other matters.

The IARU HQ Web Site is at:-

And the Region-1 site (Europe & Africa) is

Peter Chadwick Meeting
Raffle table with Geoff, G7KLV (left) & Peter Graves.

Report by CARS Member, Murray, G6JYB.

Peter Chadwick Meeting
CARS Vice Chairman, Martyn reading out a notice.

Thank you Peter for such an interesting and well presented evening.

July Meeting - "Constructors Competition for the M1FDE Shield"
Organised by Carl Thomson, G3PEM.

Anthony, M1FDE - Silent Key
Anthony, M1FDE with the PRR Radio.
On Tuesday 7th July the Chelmsford Amateur Radio Society (CARS) held its Annual Constructor's Competition.

This year a new trophy will be awarded, the M1FDE Shield.   This trophy has been created in memory of Anthony Martin, M1FDE who passed away last year at the age of 41.   Anthony was a pioneer of the Personal Role Radio (PRR) introduced into the British Army in 2002, for which he was responsible for the RF design. Prior to its use the infantry could only communicate with each other via hand signals and shouting.   The PRR is now seen regularly on TV news reports being used by UK and Allied forces in Iraq and Afghanistan.

He devoted much of his spare time to Amateur Radio Training.   He taught every Thursday evening at the Foundation, Intermediate and Advanced courses run by the Chelmsford Amateur Radio Society in Danbury Village Hall.   Over 5 years he helped more than a hundred new Amateurs get their licence.  

Anthony also served as a Committee Member of CARS and the Essex Repeater Group (ERG), ran the MB7ICM 6m Echolink node and helped establish and maintain the Chelmsford 2 metre Echolink node MB7IDA.

An enthusiastic constructor he always did well in the CARS Constructor's Competition winning several 1st prizes.
2000 3rd prize for automatic tester for audio leads
2001 2nd prize for 12 volt PSU
2002 entry for Electronic Thermostat
2003 1st prize for CTCSS Tone generator
2004 3rd prize for Digital Display Board
2005 1st prize for Packet TNC
2006 1st prize for Triplexer
2007 working in Dorset so unable to enter
2008 2nd prize for Remote Station Shutdown Unit

Anthony was keen to encourage home construction and he was always willing to help others with any problems they might encounter when making a project.

Carl will issue judging sheets for the audience to mark the projects entered.

There are very few Rules.

  • CARS Members only maybe awarded the M1FDE Trophy
  • Visitors are encouraged to demonstrate their handywork and maybe awarded the "Special Prize"
  • One can enter photographs or drawings if it is like a Power Station in size & difficult to bring.
  • It should be electrically safe.
  • It can be anything remotly connected with Radio (a house brick won it 20 years ago!)
  • CARS would like a small piece of paper with Name, Call-Sign & what the Entry is written on it.

CARS awards real money - £10 for First, £7 for Second, £5 for Third and £5 for a "Special Award".

Chairman John, G8DET introduced the Competition by showing the M1FDE Shield which will be presented at the AGM in October.

To start the photographs off Colin is seen here holding an "Electrical snake" in the form of a coiled extension lead used to supply a light at the recent NFD in Sandford Mill.   During the dark hours two Amateur Bands suffered considerable local interference which only cleared when this cable was removed from the mains supply in the morning.   Colin showed on a MFJ Aerial Analyser that it tuned those Bands and presented a 50 Ohm Load! - Moral - DO NOT USE COILED LEADS IN AN RF FIELD!

Constructors Competition
Colin, G0TRM with his "Interference Snake"
Photos by John, G8DET using Colin's camera.

Patrick, M0XAP was first off to describe a Valve, AM Transmitter he had constructed.

Constructors Competition

He said he would have liked in hindsight to have built the VFO in a separate die-cast box.   The TX worked well - it was nice to see Valve equipment again. Patrick said Loading it to an Aerial was easy - the Loading coli was wound on a Chillie Pot ("Hot fire" commented one wag).

Tip, test plastic (not metal!) by putting it in the Microwave oven for 1 minute. - If it busts into flame it is no good for RF.   If it does not get warm - great for RF.   Don't forget to put a beaker of cold water in the Microwave to protect the Magnetron as well.

Kenneth Pallant, G0OSI was next to describe his home constructed 12 Volt 5Amp PSU.

Constructors Competition
Ken said that nearly all the bits were in his junk boxes except the case which was modified for the PSU - it had cooling holes drilled in the top to let the hot air out.   It proved stable & did not suffer from RF Feedback due possibly to its simplicity.

It was the first item he had ever presented to the Constructor's Competition.

Colin then showed the Meeting the Triplexer that the Late Anthony had produced for the 2006 Constructor's Competition with which he won First Prize.

Constructors Competition
Peter, 2E0ZBU (left) looking at Chairman John arranging the PowerPoint presentation with his Son, Richard, 2E0SBU looking on.

Peter introduced the project which was the construction and operation of a Magnetometer.

It was based on a pair of custom magnetic sensor chips produced for the Robot industry - to enable the robot to know where it is by measuring the strength and direction of the Earth's Magnetic Field.

Richard then descibed the construction of the unit which was build in two parts - one part put at the top of their garden to be away from any magnetic fields in the house.   A ZigBee (which uses Wi Fi frequencies) link connected the two parts.

Peter then showed graphs of results including a large transition one day - this was also recorded in other parts of the UK by existing Magnetic Field recording equipment so he said that gave them confidence their equipment was working well.

Constructors Competition
Photo of the Magnetometer - the ZigBee RX can be seen attached to the top right of the laptop display.
It is run by a 12Volt battery topped up by a 5Watt Solar Panel.

Colin concluded the Competion by demonstrating a Morse Display Board he had made for CARS events at Sandford Mill.

Constructors Competition
Colin described the Display Board which used modules from MFJ, a computer Keyboard and a Morse Key.

Earlier on in the day he had tried to print out the results on a Dot Matrix Printer but it blew-up the PSU.   Fortunately Geoff, G7KLV had the information regarding a spare Regulator so that was replaced with a fiddle!

The Morse Key was used by Colin to produce a series of notes which CARS Morse expert, Gwyn, G4FKH said was "rubbish" to the amusement of the meeting!

Next the Keyboard was used with similar results but the "Ending characters" were deemed "OK".

The Meeting was then given 15 Minutes to Judge the entries and to give their results to Carl by 9PM.

During the period of Judging Richard is seen here describing in more detail the Magnetometer.

Constructors Competition

After the Break the Raffle was drawn.

Constructors Competition
Richard, 2E0SBU reading out a Raffle winner's number with the basket being held by Chairman John.
Photo by Colin, G0TRM.

Carl totted up the score and anounced the winners.
Constructors Competition

Carl is standing behind the Magnetometer display which shows results.  

Constructors Competition
Cars President Harry, G5HF presenting the 3rd Prize to Colin (left) and Second Prize to Partick.

Constructors Competition
Cars President Harry, G5HF presenting the Special Prize to Kenneth.

Constructors Competition
Harry, G5HF presenting the First Prize to Richard, 2E0SBU.
Richard will also receive the M1FDE Shield at the AGM in October - Congratulations.

After the Prize-giving, Mark Sanderson, M0IEO presented his idea of commemorating the USAF, 100th Bomber Group's involvement with Thorpe Abbotts near Digglebugh (Norwich).

While on holiday ealier in the year he happened to stumble on this Museum and since has obtained permission to set up a Special Event Station by the Chairman of the Museum and by Ofcom.

Constructors Competition
Mark looking at the screen with a photograph of the Control Tower at Thorpe Abbotts.

This was restored in 1977 and granted a 99 year lease.   It is open on Wednesdays, Saturdays and Sundays during the Summer.

Mark has from 5pm on Friday, the 11th to Sunday evening, the 13th September as the period he wishes to operate from this site and invites the Diss Radio Amateur Radio Society to assist with the project as well as CARS Members.

Contact Mark at     "belinda.sanderson at"

Thanks to all who made the evening the success it was.

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©Copyright CARS 2009
Last revised:- 6th September to update the page.