Amateur Radio July 2008
Delivery expected from 7 July 2008
Editorial
Here we are in July already – half the year has already passed. For me, there will be an all too brief small reduction in pressure at work before the start of the second half of the year.
WIA AGM
It was good to see so many people in Broken Hill for the WIA AGM in late May. It was a very long drive from Churchill, which was fortunately broken up in both directions by overnight stays with other amateurs.
On the trip to the AGM, Barry VK3BJM had offered a bed. It was great to catch up, even if only for a couple of hours on the Thursday evening before adopting horizontal polarisation. A brief chat over coffee in the morning allowed a quick look over the shack before hitting the road again.
In Broken Hill, there were lots of people to meet and many others with whom to renew contact. I even managed a little time to play some VHF radio – see the VHF/UHF column for an outline.
The return trip involved a “short” three-hour drive to Mildura, arriving early enough to drop into one winery to sample some of the produce. Then it was to the home of Geoff VK3ACZ and Marilyn VK3DMS for dinner and more discussion, enlivened by the presence of Christine VK5CTY, who was to spend a few days in Mildura. The next morning saw us back on the road for the trip home – fortunately an easy trip with few traffic hold ups resulted in only 8.5 hours travel time.
The atmosphere was excellent at all the WIA organised events. We have a photo essay in the centre pages showing some of the visual highlights.
Drawings in AR
Some time ago, I made a call for assistance in the production of drawings for production in AR.
Indications are that we have a volunteer to assist Bill VK3BR in the production of circuit diagrams, using one of the standard electronic design packages.
However, many of the drawings required do not work well unless prepared using a true CAD drafting package, for example TurboCAD, AutoCAD or similar packages. Most of the non-circuit diagrams are prepared using such a package. Are you a reader with skills in the use of such a package, who can prepare a drawing in your spare time on the odd occasion? If so, let me know and Bill will send you a sample task. Like so many of the jobs undertaken for the WIA, this too will be a volunteer task – giving you a chance to give a little back to our hobby.
Callbook and AR cover photos
Thanks to those that have sent photos for consideration for the 2009 Callbook cover and/or for AR. We do need a greater selection of photos to be available, so that we can prepare covers of sufficient quality. Digital images are best; at as high a resolution as you can produce. Feel free to send the images at lower size and resolution, but remember to let us know the file size of the original to assist us in assessing whether the image/s will be usable for the required task.
AR articles
Articles for consideration for publication in AR have been coming in slowly over the past couple of months – so much so that the technical editors have reduced the list for review to almost empty. Our thanks go to all who have contributed to date. We will soon be in need of new material – so please put fingers to keyboard and tell us all about the latest project in the shack, or even about the last club event. Remember that there are hints available on the WIA website – look under Members, AR magazine, Contributing material.
Did you venture out for the inaugural Winter VHF/UHF Field Day? If so, let us all know how it went for you and do not forget the photos.
By the time this magazine arrives in your mail box, it will be time for GippsTech2008. Once again, I look forward to catching up with so many amateur friends at the event. Of course, I will be on the look out to find someone to prepare a report for the August issue!
Cheers,
Peter VK3KAI
Cover
ALARA was well represented at the WIA AGM in Broken Hill. The backdrop to the group, photographed at the AGM Dinner, is a sculpture that recognises the sacrifice of those from Broken Hill and district in war, located in the foyer of the Broken Hill Entertainment Centre. L-R Lesley VK5HLS, Dot VK3DB, Jeanne VK5JQ, Susie VK5FSUE, Lia VK3LPH, Marilyn VK3DMS, Kathi VK6KTS, Jenny VK5FJAY, Meg VK5YG, and Christine VK5CTY. The inset shows Brenda Edmonds VK3KT with her certificate for the Ron Wilkinson Achievement Award.
Photos by Peter Freeman VK3KAI.
Table Of Contents
GENERAL
A state gathering of radio amateurs in the Czech Republic: Vlad Sezemsky VK2EKO and Margaret Sezemsky VK2PSM.
It all started on a wet wintry evening: Kevin Mulcahy VK2CE
When one can’t see the forest for the trees: Felix Scerri VK4FUQ
Views from Broken Hill: Compiled by Peter Freeman VK3KAI
2008 WIA Grants scheme launched: Geoff Atkinson VK3AFA
So you want to give CW a try?: Brett Rees VK2TMG.
TECHNICAL
Triangle of six metre dipoles: Neville Chivers VK2YO
Now for something completely different. Part 1 - A high power class-E amplifier for 40 metres: Phil Wait VK2DKN
Repairing an Icom PS-30 power supply: Warren Stirling VK3XSW
A simple two element ‘Strip’ Yagi for fox hunting or other applications Felix Scerri: VK4FUQ.
An LF receiving converter with loop-stick antenna: Drew Diamond VK3XU
A state gathering of radio amateurs in the Czech Republic
Vlad Sezemsky VK2EKO and Margaret Sezemsky VK2PSM
This month we have a report from the Czech Republic about a state gathering of radio amateurs in the town of Holice. This is a regular meeting place for European amateurs, and for the first time last year, Australian was represented, by Vlad VK2EKO. Here is an article full of local colour, including the Mayor, and a reminder that amateur radio is truly an international passion.
Views from Broken Hill
Peter Freeman VK3KAI
Broken Hill took the WIA to its heart, and made sure that all those who travelled so far to attend the AGM were made most welcome. This was another mile-stone for the WIA, both in the ongoing progress reported at the business meeting, and in the enjoyable social and cultural activities that rounded out a very special weekend for all involved.
Turn to pages 28/29 for a photographic record of the people, places and events that highlighted the occasion. These excellent colour photos were taken by Christine Taylor VK5CTY, Peter Freeman VK3KAI (Amateur Radio Editor), Ewan McLeod VK4ERM and Robert Broomhead VK3KRB.
Now for something completely different. Part 1 - A high power class-E amplifier for 40 metres
Phil Wait VK2DKN
If you are into home-brew and the latest technology, you will be keen to construct the class-E amplifier described by Phil Wait VK2DKN. Turn to page 6 for this detailed article on how to exploit the high-efficiency performance of MOSFETs operating in the new Class-E mode. It is fully compatible with modern digital modulation techniques but not suitable for SSB or similar low-level modulation systems. Phil explains the operation of Class-E amplifiers and a detailed circuit is included. Plus guidance on construction methods – and a few words of warning!
An LF receiving converter with loop-stick antenna
Drew Diamond VK3XU
No better introduction to this article could be forthcoming than those of Drew himself, in his opening to the article itself –
Interest in exploring low frequency (LF) techniques has been re-kindled in this country by the likely approval for Australian Advanced amateur licensees to use 135.7 to 137.8 kHz (2,200 metres) for narrow-band modes.
Unfortunately, most households and/or neighbourhoods are now enveloped in an ‘electronic smog’ of spurious noise plus a galaxy of harmonics from a multitude of switch-mode power supplies and other appliances. Rather than use the main transmitting antenna for receiving, much better results should be obtained where a loop, either ‘frame’ style, or ferrite rod (loop-stick) is used. Such antennas possess a deep null in their response that usually permits the worst of these noise sources to be placed ‘in the null’, and so obtain a substantial improvement in signal to noise.
A significant reduction in noise may be had by making the converter self-contained and battery operated, with no electrical connection whatsoever with the AC mains (which conducts, and re-radiates noise into the shack environment). For a loop-stick antenna, a further decrease in mains-born noise pick-up is obtained where the antenna is located more than a one metre or so from mains operated devices.
Offered here is a simple, sensitive receiving converter that allows an ordinary HF receiver - one that tunes the 3 or 4 MHz bands - to be used as a 'tuneable IF'. Hence, where a signal on, for example, 137 kHz is tuned in, it will be ‘up-converted’ and appear on 3,137 (or 4,137) kHz.
Drew’s solution is, as always, well thought out, simple (relatively, for those with some similar experience) to construct and effective.
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Page Last Updated: Wednesday 9 July 2008 at 9:43 hours
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