Ragchew Summer 2018

SPECIAL EVENT STATION GB2WFB AT WORTHING FIRE BRIGADE’S OPEN DAY

“One of this year’s highlights was the Club BBQ at Goring Gap” – Alan G4GNX Plus JONATHAN G1EXG’S SHORT CIRCUIT CHAIRMAN’S CHATTER CORRESPONDENCE RALLIES

Summer 2018

Worthing & District Amateur Radio Club Established 1948 Website: www.wadarc.org.uk

E-mail: info@wadarc.org.uk President: Chris Smith G3UFS WADARC meets every Wednesday at 7.30pm for an 8pm start in the Lions Hall, 21 Roberts Road, Lancing BN15 8AR. All who have an interest in radio communications and associate subjects, whether a licensed amateur or not, are welcome. WADARC can also arrange training for the radio amateur Foundation, Intermediate and Advanced licences.

The WADARC Committee 2017 – 2018 Chairman Alan Baker G4GNX Vice-Chairman Leslie Sampson G3JSU Secretary Andy Braeman M6RFE Treasurer Roger Ferrand G7VBR Raymond Ellett M6IKO Norman Jacobs 2E0RKO Ian MacDonald M0IAD Alex Slee 2E0UMD These Committee and Members have volunteered to accept the following responsibilities: Membership Manager Ian MacDonald M0IAD Ragchew Editor Roger Hall G4TNT Website Andrew Cheeseman G1VUP / Alastair Weller M0OAL Special Events Stations Peter Head G4LKW Online Content Coordinator Alan Baker G4GNX Outside Events Coordinator, Facilities and Bookings Norman Jacobs 2E0RKO Training Coordinators Alastair Weller M0OAL / Andrew Cheeseman G1VUP Exam Secretary Alastair Weller M0OAL Press and Publicity Coordinator Les Sampson G3JSU Quartermasters Andy Braeman M6RFE / Raymond Ellett M6IKO Club Calendar Coordinator Alex Slee 2E0UMD Weekly News Email Phil Godbold G4UDU, Alan Baker G4GNX, Jonathan Hare G1EXG

WADARC Club Nets (all times are local) 07.30

Sunday

3.725MHz ± QRM SSB

19.30

Monday

145.425MHz (V34/S17)

11.00

Thursday

7.106MHz ± QRM SSB

CONTENTS

Editorial .................................................. 4 Chairman’s Chatter ................................ 6 GB2WFB by Edmund M0MNG ......................... 8 Marconi’s Predecessors by Ted G3EUE ......... 12 Short Circuits by Jonathan G1EXG .................... 15 Rallies ..................................................... 16

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EDITORIAL

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elcome once again to the latest edition of Ragchew. It’s a bit thin this time and that’s for the usual reason, there’s been a lack of material sent in. It might be because it’s summer and many members are away on holiday but for whatever reason, I didn’t have much to put in this issue.

I wouldn’t normally publish an issue with so little content but as this one is labelled Summer 2018, I really have to get it out while there are still a few weeks of Summer left.

In This Issue Ted G3EUE wrote in with an interesting look at Marconi’s predecessors and suggests Marconi was, in the words of Isaac Newton, “…standing

on the shoulders of giants”.

Jonathan G1EXG’s Short Circuit column this time is devoted to magnetic amplifiers, which are used as an effective way of controlling the power flowing in AC circuits. He explains how they work, what they do and how they are used.

Edmund M0MNG kindly sent in an article about his experiences at this year’s special event station GB2WFB at the Worthing Fire Brigade’s Open Day. It was a successful day, marred only by a bit of petty vandalism.

We don’t have any Presidential Ponderings this time but our esteemed Chairman does share his thoughts with us and then we finish this issue with a list of forthcoming rallies for the next couple of months.

Ragchew You might have noticed a small change to the way Ragchew looks on the Club’s website. I use a company called Issuu to provide the pageturning version of the journal. The annual subscription is just over a couple of hundred dollars a year but it hasn’t cost the Club anything because my company, PW Publishing Limited, has been paying for it.

PW was using the platform for the small page-turning sample issues we put on our website and it’s been easy (and free) to piggyback Ragchew onto our subscription. That subscription has now run out and because I’ve now retired and closed the company, it won’t be renewed. That

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C means we’ve now reverted to the basic free service, which is why you’re going to see adverts on the web page. I don’t think they’re intrusive and I’d definitely rather have them there instead of having the Club pay about £200 a year just to get rid of them – what do you think?

Taking that thought a stage further, do you want a page-turning version? In the past, some members said they would be happy with just a plain PDF version and they never read the online one. Would you be happy to have just a PDF version that is either emailed to you as soon as it comes out or that could be downloaded from our website?

Here’s an even more radical question – do we still need to publish Ragchew? Years ago, it was the only way of keeping up to date with Club news, of finding out about future meetings, of reading reports about Club activities and it was how the Committee disseminated information.

Nowadays, the internet is used for almost all those things.

There are now at least five ways of communicating with members and Ragchew is by far the slowest, which is probably why members are using the reflector, our website and to a lesser extent our Facebook page and YouTube instead. For example, I used to get reports about outside events the Club had taken part in but that seems to have almost died out with just one or two people still bothering. Instead, the trend now seems to be for members to put a brief piece on the reflector or a video on YouTube. There’s nothing wrong with that and it gets the news out far more quickly than waiting for a quarterly publication but it does mean Ragchew is getting thinner year on year as the material dries up. That’s why I’m wondering if there’s now a case for scrapping Ragchew in its current form and beefing up the weekly newsletter, the website and the Facebook page instead. Perhaps the newsletter could become a sort of weekly Ragchew. What do you think?

Finally If you have anything you’d like to contribute to the next issue or if you have any thoughts you’d like to share on the future of Ragchew, please do get in touch with me at ragchew@wadarc.org.uk 73, Roger G4TNT

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CHAIRMAN’S CHATTER

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irst, an apology for not being able to take part in as many Club activities as I would have liked to but I have recently undergone some serious neck and spine surgery. I now seem to be recovering from it quite well but a full recovery will take a bit longer (if it ever happens).

Outdoor Events In the meantime, your committee and other members have been working hard to keep the Club running as smoothly as possible and as you may imagine, a lot of effort went into organising the outdoor events that took place during the summer.

We’ve been atop local hills, including Mills on the Air and DX chasing from Chantry and other lofty places. A lot lower down, we’ve set up stations at Worthing Fire Station and Shoreham Lighthouse, with a record number of QSOs during ILLW. One of our general meeting highlights was Alastair M0OAL the barbecue at Goring Gap, where Alastair M0OAL very ably cooked a selection of food for members and guests. As we’re unlikely to be able to meet at Derrick’s for our usual annual barbecue for the foreseeable future, we may well have further gatherings at Goring Gap, if we can find someone who’s willing to organise the barbecue and cook the food. If you think you can help, please do let me know – it would be nice if we could make this a regular event.

Some of our outdoor gear has been updated or will be soon. We’ve purchased new sides for the club gazebo and we’ll be acquiring some canvas bags to carry our tent poles as the existing cardboard boxes are worn out and out of warranty! If any of you can think of anything else that needs repairing, replacing or updating, please tell me or any member of the committee.

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Foxhunts have been popular with a total of three taking place this year.

Some of our members are getting very good at direction finding and the less able bodied have been able to follow their progress using handhelds from within Lions Hall. I think we now have the balance about right but if you would like a different format or perhaps more or fewer events, please let me know.

Repeaters Thanks to Alastair, Ian and Phil, our repeater GB3WO has recently been moved to a new (permanent) location at Worthing Town Hall. I hope that many of you who haven’t previously thought about using it will now do so and encourage others to take the opportunity to use one of our Club assets which is available 24/7.

Further servicing is being carried out on the actual repeater for GB7JH. We’re looking at replacing the computer for something newer and more reliable and then we’ll work on a suitable location to rehouse it all.

Lions Hall Lions Hall continues to suit our purposes although there has been some muttering amongst members about parking difficulties. Unfortunately, the Hall is in a residential street and on-street parking spaces are at a premium in the evenings. We’re looking at a couple of other premises with their own carparks but we don’t want to move very far from the current premises, so if we decide to move, we will be choosing carefully and you’ll all be kept informed.

Finally It’s time for a reminder that we will be holding a construction competition in the coming weeks. If you want to take part, it’s time to start constructing.

Also, another reminder that subscriptions are now due. If you haven’t paid yet, please contact Ian M0IAD or Roger G7VBR. Please note, unless you’re a fully paid-up member of WADARC, you can’t vote at the AGM, which is fast approaching!

73, Alan G4GNX

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FEATURE GB2WFB AT WORTHING FIRE BRIGADE Edmund M0MNG reports on GB2WFB, the special event station that WADARC members operated at the Worthing Fire Brigade’s Open Day.

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was the first to arrive on site at 0800 on Saturday 21st July for the annual Worthing Fire Station Open Day. Preparations were already well advanced as the gazebo and Carolina Windom antenna had been put up the evening before and a very bulky cable ran from the gazebo into the fire station for mains electricity.

This was a welcome change from 2017 when, bizarrely and unprecedentedly, we were told we had to take our power from an onsite generator. This was reputedly more reliable than the mains power had been the year before although none of us there could actually recall any mains problems in 2016. However, we did have a couple of power cuts in 2017, including when somebody accidentally unplugged us from the generator!

Setting Up As the setting up was so far advanced, I thought to myself, “Well all we need now is somebody to turn up with a transceiver, turn the power on and we can be on the air in a few minutes.” Unfortunately, life is rarely that simple!

Pete G4LKW, Pete 2E0FVL and Roger G7VBR arrived soon afterwards and Pete then recounted the tale of the antenna, which is always held aloft by the training tower at one end and a conveniently-located large conifer at the other. Pete always uses a catapult to fire a line into the tree and his first shot on the Friday evening had been really successful, both in terms of height and position.

Unfortunately, a knot came undone, which meant that he had to bring the

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C antenna down then start again from scratch. He did manage to get the antenna back up in the tree eventually but in a slightly less advantageous position than his first effort – and after only seven attempts!

Roger then noticed that one of the guy ropes holding down our gazebo was no longer attached to the peg in the ground. It looked as though the rope had been cut. Our immediate reaction was to wonder if one of the other vehicles setting up nearby had managed to damage it somehow.

However, Roger soon discovered it was no accident. The guy rope at the opposite corner of the gazebo had been cut as well and the perpetrator had even gone to the trouble of chopping it up into several little pieces and scattering those on the ground. It would have been impossible to tie them back together and repair the rope.

Fortunately, Pete had some spare guy rope in his van, so replacements were installed in a matter of minutes. Sometimes I wish my parents had made me go to Scouts; the skills they teach there would have served me well on days like these.

The odd and rather concerning thing was that there was no other damage to our gazebo and none of the other stalls appeared to have been targeted in any way. In theory, the school field where the event takes place is secured overnight. Thank goodness we hadn't left any transceivers or other expensive gear on site! Have any WADARC members upset anybody recently?

They say that things often come in threes and this time the third thing was when we found we had a lack of mains electricity. The six-way extension lead we use at this event has a built-in Residual Current Device (RCD). I am sure that I don't need to explain what an RCD is, how it works, or why using one at a public outdoor event is a very sensible safety measure!

The problem was that we could not latch the RCD into the on position, even with nothing plugged into the socket board. My first thought was that the RCD itself had failed, possibly due to age. I know we’ve used this same extension lead at many previous events.

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C Pete drove home to fetch an equivalent mains lead but in the meantime, Roger had the excellent idea of replacing the 13A fuse in the plug. This solved the problem, although I still have no idea what caused the original fuse to fail in the first place.

On the Air By 0930 I was beginning to wonder if somebody was trying to tell us something and if GB2WFB would even end up going on the air at all.

Happily, at 1000 we were able to launch straight onto 40m SSB and conditions were a lot better than I feared they might be. The vast majority of our contacts were interG. The contacts flowed on 40m during the first couple of hours but then over lunchtime and the early afternoon the going predictably became more difficult.

The temperature wasn't too bad in the morning but at lunchtime the light clouds cleared and the sun came out. The tent then became uncomfortably hot and humid to the extent that Roger removed the back wall to allow a breeze to flow through! This year is undoubtedly the hottest GB2WFB that I have ever experienced and I'm hoping for much cooler temperatures in future years!

From 1515 until the event closed at 1600, we moved to 17m and had a string of contacts all across continental Europe. I am sure that we benefited from Sporadic E with a relatively short skip distance.

One person mentioned on air that 10m was open as well but our frequency had been spotted on the DX Cluster by then and this

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C had generated a mini pile-up so we never had a chance to move to 10m before the event closed.

Visitors We also had three contacts through GB3WO – Andy G3UEQ/M, Sean 2E0XBT Contacts and Alex 2E0UMD/M. Sean and Alex came We had 48 QSOs altogether: to visit us, possibly encouraged by my 37 on 40m SSB positive descriptions of the event and the 8 on 17m SSB lovely homemade cakes! If you have never 3 on 70cms via GB3WO visited this event, then I encourage you to come along in 2019. You don't know what you're missing!

Thank you to everybody who popped in to see us. In addition to the amateurs already mentioned, we were pleased to welcome Brian G0SIU, Terry G0BRP, Rod G3YHM, Nigel G3YSW, Barry G4GPW along with Alan M6WHH. My sincere apologies if I have forgotten anybody.

Finally This year will be memorable partly for the obstacles facing us before we even went on the air but also for the colour of the grass at the event. There was barely a trace of green because the previous month or so had brought little or no rain and high temperatures every day. I have visited GB2WFB almost every year since I became licensed in 2009 and I had never seen the grass looking like this. At a distance you could have been forgiven for thinking you were looking at dust or dirt.

It was a very enjoyable event and if you’d like to see more about it, I’ve made a YouTube video that you can view at: https://www.youtube.com/watch?v=-ljc7q4-ffI 73, Edmund M0MNG

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G1EXG’S SHORT CIRCUITS This time Jonathan G1EXG takes a look at magnetic amplifiers and explains how they work, what they do and how they are used.

SHORT CIRCUIT NO. 19: MAGNETIC AMPLIFIERS

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agnetic amplifiers are a simple, rugged and effective way of controlling the power flowing in AC circuits. They were used in the early high-power AM modulated radio transmitters and are still used in high-power welding supplies as well as in switch mode power supplies. Generally, they are not well known so here I will describe in simple terms how they work.

Phase If you put an inductor in series with an AC powered load, it will create a phase difference or shift between the voltage and current in the series circuit and so change the power flowing into the load. If the inductor was a variable device you could, in principle, adjust it to vary the power flowing into the load.

Magnetic material such as ferrite have a high permeability which means that coils of wire wound around ferrite will have a much greater inductance than if they are empty or air cored. However, the permeability is sensitive to the strength of the static magnetic field it experiences in the coil or the vicinity of the material.

Try this simple experiment to test the magnetic field sensitivity of ferrite.

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C A medium or longwave radio will have a ferrite rod antenna inside the case. Tune slightly off from a station and bring a magnet near to the radio (a few centimetres or so). The magnetic field will either cause the tuning to shift 'onto' the station and the audio quality will improve or the field will detune the coil completely and you will lose the station.

Going back to our series circuit with the power controlling variable inductor, if the inductor is wound on a ferrite material, we can add a second set of winding coils to the inductor and use a DC current to create a magnetic field through the ferrite. This will change the permeability leading to a change in the inductance. In fact, the core permeability can change so much that it no longer functions at all and we say the core has become saturated. At this point the inductance rapidly reduces and the power flowing in the AC circuit will increase.

The circuit looks like a standard transformer layout but I hope you can see that it actually works differently. If an AC current is flowing in the inductor, the DC control current can set the point at which the core will saturate, which will abruptly increase the current. The length of these high current pulses can be varied by the DC control current and so gain control over the average power flowing in the AC circuit – this arrangement is called a magnetic amplifier.

In Use In the past power control circuits like these were used to control theatre lights on stage for example – kilowatt lights could be controlled using a

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C few amps in the control circuit so you can see why the circuit is called a magnetic amplifier. What I have outlined here shows the basic principles but more complicated circuits were usually used in practice. For example, two separate cores were often used, each with a control current winding but wired in reverse series. Any unwanted current flowing back into the low power control current circuit, from the high-power AC circuit, would then cancel each other.

You can have more than one set of control current windings, which means you can use magnetic amplifiers as summing inputs for complex applications and they were used in early analogue computers.

Modern Uses These days Mosfet and other semiconductor circuits have mostly replaced magnetic amplifiers. However, there are a few areas where they are still used. For example, semiconductor devices do not handle high radiation environments well (such as high neutron fluxes). Radiation can cause electrons to be released in the material, changing the conductivity and performance of transistors and chips as well as causing permanent damage.

Magnetic amplifiers use the magnetic field to control current so are not affected in the same way and they create rugged circuits that have found application in nuclear power stations and spacecraft.

73, Jonathan G1EXG

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CORRESPONDENCE LIFE BEFORE MARCONI Ted G3EUE has written in with thoughts on Marconi’s predecessors.

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n Dundee there stands an obelisk to the memory of Mr J A Lindsay who died in 1862. On one of the panels we are told he was, “A pioneer in electrical science; he foretold the application of electricity as an illuminant, a motive power to replace steam and a substitute for coal in heating. He devised an electric telegraph in 1832; suggested welding by electricity and produced a continuous electric light in 1835; proposed a submarine telegraph in 1843 and accomplished wireless telegraphy through water in 1853."

Clark Maxwell followed Lindsay and in a lecture before the Royal Society, he submitted that wireless telegraphy would be possible by means of electrical magnetic waves, the velocity of which, he concluded, was the same as light – a conclusion subsequently found to be correct.

In 1879 David Edward Hughes found that a microphone reproduced sound from a telephone when at some little distance from the coils through which current was passing.

In 1885 Sir William Preece sent signals between two insulated squares of wire 400 yards apart and later improved the distance to 4.5 miles between the parallel telegraph wires. In 1892 he communicated between the Welsh coast and the island of Flatholm, three and a half miles away.

By 1887 Hertz had made his discoveries and transmitted signals across a room by discharging electricity from a Leyden jar.

In 1895, at about the time as Hertz died, Sir Oliver Lodge demonstrated that wireless messages could be sent across the room by means of Hertzian waves, using as a detector the ‘coherer’ invented by a French electrician Branly.

Perhaps it should be remembered that Marconi commenced his own experiments around 1888, following reports of the work by Hertz.

73, Ted Jones G3EUE

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RALLIES SPRING 2018 AUGUST 12th – Flight Refuelling ARS Hamfest Cobham Sports and Social Club Ground, Merley, Wimborne, Dorset BH21 3DA 19th – The RATS (Rugby Amateur Radio Society) Rally Princethorpe College, Princethorpe, Rugby CV23 9PY 26th – Torbay ARS Annual Communications Fair The Racecourse, Newton Road, Newton Abbot, Devon TQ12 3AF 26th – Milton Keynes ARS 60th Anniversary Rally Irish Centre, Manor Field, Bletchley, Milton Keynes MK2 2HZ 27th – Huntingdonshire ARS Annual Rally

SEPTEMBER 2nd – Telford Hamfest Enginuity Centre, Coalbrookdale, Telford, TF8 7DQ. 8th – Caister Lifeboat Radio Rally Tan Lane, Caister on Sea NR30 5DJ. 15-16th – BATC Convention Midlands Air Museum 15th – FOG ON THE TYNE RALLY Whitehall Road Methodist Church Hall, Bensham, Gateshead NE8 4LH 16th – WESTON-SUPER-MARE RALLY 28-29th – NATIONAL HAMFEST Newark & Nottinghamshire Showground, Lincoln Road, Newark NG24 2NY 30th – Pencoed ARC Table Top Sale Pencoed Rugby Football Club, Felindre Road, Pencoed CF35 5PB 30th – Belgium Amateur Radio & Computer Rally LOUVEXPO, rue Michel Debauque/Arthur Delaby, La Louvière

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