Chelmsford Amateur Radio Society
G0MWT, GX0MWT, GB5HF & M2T

Past Club Meetings: July to September 2006


September Meeting, 2006. RSGB Editor, Alex Kearns, M3LSZ.

Alex Kearns was invited to attend CARS to inform us of how he is getting on with his new job as Editor of RadCom.

Alex Kearns M3LSZ

Alex Kearns took up the editorship of RadCom just over a year ago. He had previously been editor of European Semiconductor Magazine and before that had written for EN The Magazine for Entrepreneurs.

In the last year he introduced a number of significant changes to the magazine. In this talk, Alex provided a brief history of RadCom from its early days as the Bulletin and spoke about some of the personalities that have been involved in the magazine and finally outline his vision for moving RadCom forward.

Alex Kearns, M3LSZ
Photograph by John, G8DET.

Alex said "Amateur radio is arguably at a turning point with new technology, notably software defined radio, set to change the hobby forever. As editor of RadCom, my job is to ensure that RadCom keeps up with these pioneering changes while at the same time ensuring that we don't neglect amateur radio's rich and varied history."

Then Alex played a nice RSGB Video which explained to workings of getting RadCom into print.

Looking at the RSGB Video
Photograph by John, G8DET.

After showing the Video, Alex was asked to present 3 Chelmsford Awards. This Award is to promote CARS and the proceeds will go the the Essex Air Ambulance, a service supported mainly by donations.

Martyn explaining his Award made using Echolink Martyn receiving his Award
Martyn explaining how he acheived the Award using only Echolink & right, receiving the Award. Photographs by John, G8DET.

Colin receiving his Award Colin showing the Special Event QSL Cards which made up his Award
Colin receiving his Award & showing the Special Event QSL Cards which made up his Award. Photographs by John, G8DET.

Award Group

Award Group - Brian, G3CVI; Martyn, M0VAM; Alex & Colin, G0TRM.
Photograph by Trevor, M5AKA.

After the Presentation there was a lively but constructive interchange between CARS Members & Alex. We hope to see some of our suggestions in later issues of RadCom.

Thank you Alex for coming a presenting a very interesting evening.

Thank you also to Colin for doing the sound & buying the Raffle prizes & Denis for manning the Raffle Stand.



August Meeting:-
Table Top Sale
Organised by Colin, G0TRM

At this year's Tabletop sale approaching 100 Members and visitors enjoyed viewing, and in some cases buying a whole range of new and not so new electronic and other radio related items. We had visitors from far afield, some traveling a good distance to attend. A few faces present on the night, were also seen at the Colchester Rally a day or two before.

As usual, the event was widely advertised both in the local press and on local radio. Readers of Radcom, P W and S W M and other radio magazines had all the necessary information clearly displayed. Many leaflets were produced for display in local libraries, bookshops and public notice boards. Many thanks to the large number of Club Members who came along to sell or to buy or maybe to chat, contributing to a great atmosphere. Thanks too, to those who donated for sale, some very fine items to be sold for Club funds.

Thanks to Geoff KLV for his part in raising a good sum by selling in quantity, many items given freely by Fred, G2HNF. Thank you Fred.

CARS Minute Secretary Jim, 2E0JPS also made an excellent contribution by selling a number of donated items of equipment. Event Secretary Martyn, G1EFL was pleased with the success he obtained selling the Club related merchandise.

Our thanks to Steve, G4ZUL for organizing as a solo effort, the excellent raffle, with the results helping to boost the Club coffers.

Once again, the evening, both socially and financially was deemed a success. Finally, my thanks to all who played any part in helping to make it a very worthwhile event, My thanks to all who contributed to the evening.

Report by Colin, G0TRM

Many thanks to David Barber, G8OQW for demonstrating the home station's FT9000.

Editorial Comment. A number of Members have said how much they enjoyed the Social aspects of the Table Top Meeting (besides spending money!).

We will run the Table Top Sale again next year - look out for it in our 2007 Programme.



July Meeting - Software Controlled Radios & the new BR68 by Murray Niman, G6JYB

The meeting started with Geoff, G3EDM explaining that he had been working Australia for the past 60 years & therefore had made a number of friends in VK land. A while ago he had been contacted as a Vice President of CARS for contacts for a forthcomining event, namely the 100th year ago Marconi made contact between Tasmainia & the mainland.
Geoff was able to supply information & to provide contacts in the UK.

Geoff showed the meeting the finished product - two nicely presented booklets.

Geoff, G3EDM
Geoff, G3EDM with the Australian Marconi booklets


Software Defined Radio - the Future is Digital!

Murray-G6JYB
Murray, G6JYB

Software Defined Radio ( essentially Digital Direct Conversion ) is part of an exciting future that promises to sweeps away large amounts of traditional analogue RF and IF circuitry, permits an amazing flexible variety of traditional and new radio modes, offers new possibilities for experimenters and cheap homebrew - and even offers more points for contesters!

Murray-G6JYB
Murray, G6JYB with his opening slide

Murray explained with the aid of simple diagrams how Software Radio works - better than in RadCom!

Murray-G6JYB
Murray, showing the Laptop display with a strong signal to the right (not tuned in)

Judge the size of the Sotware Radio by the USB Plug on the right of the PCB (below).

Surprisingly, the USB Socket is only to pick up 5volts in a tidy, lead-less manner. However some of the components on the PCB are to filter the noise this power supply provides!.

Software Radio

The Front End Tuned circiut and RF Amplifier was replaced by a simple Band Pass Filter to eliminate the receive twice frequency. The Mixer has been replaced by a 4 pulse sampling chip which by definition did not suffer from non-linerality. At a stroke this had removed all of the many wound coil tuned circuits.

PC Display
As seen on the PC

Murray-G6JYB
Photograph shows a scan of 2.3GHz using special software

Background Note: This first talk concentrated on SDR Receivers. However for anyone who has done the Advanced course or heard GB3VHF, Direct Digital Synthesis and amazing new Transmitters have also arrived.

Thank you Murray for a very interesting talk.

Post Meeting Note. Chris Chapman, G0IPU wrote a detailed Report of the SDR Meeting. If you would like a copy, see below. It is only 18KBytes in PDF Format.

Click on the link below. Having looked at it, click on your Browser's BACK button (top left) to come back to this Web Page.
If you don't you may clear your Browser!

Detailed Report by Chris, G0IPU.


After a good Raffle, Murray explained the new BR68 just issued by Ofcom.

Murray-G6JYB
Photograph of the BR68 start sequence

He highlighted some of the changes including the re-introduction of the /A Call-sign for working from an Alternative location.

This will be dealt with in detail, elsewhere.




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ęCopyright CARS 2006
Last revised:- 17th August to add the PDF write-up for Murray's talk in July.