SILVERTHORN RADIO CLUB
GB2HR GX2HR GX3SRA GX8CSA
Spurious Comments
By 2E0MDQ
Silverthorn has had a very eventful few months indeed. Foundation and Intermediate exams were held at Friday Hall back in June. I am pleased to report all that took part passed with flying colours. Dieudonne is due to be taking his Foundation course in the very near future. I have begun work on the advanced course and understand that we have had enquires from interested parties asking when we will be running this course. Tom M5AJK is hoping to start this course sometime in late September early October, more details will be added to the website as soon as the dates and numbers are confirmed.
The Practical Wireless 144MHz QRP contest took place in June, Leslie G0CIB and myself set up a station on Pole Hill. We didn't do badly considering the amount of time that we spent on the Hill around 4.5 hrs, using a 12v battery and 3w maximum power. The Halo antenna was getting out but didn't seem to perform as well as the ground plane vertical. Furthest contacts made, were down near Worthing and Brighton.
Check out the videos on the club website http://www.silverthornradioclub.org.uk/camps/PWQRP Contest
Club radio camp held in July at Lambourne end was a major success in every aspect, the weather was a major improvement on lasts years wash out and a fun time was had by all.
Something a bit different took place this year. Les G0CIB, Clive G8VZD & Tom M5AJK took part in a radio podcast interview with Martin Butler of the ICQ Amateur / Ham Radio podcast team which can be found on their website at http://icqpodcast.com/
Its Series Six, Episode Sixteen, entitled "Off Centre Fed Dipole".
Finally I would just like to welcome our newest member Ian G7PCQ, Ian is a seasoned amateur and is a much welcomed addition to the club. We hope you enjoy your time with us.
Michael 2E0MDQ
Chairman’s Band
BY G0PRK
A very successful four night club camp was held at Lambourne end in August. Several members made successful contacts using their own call signs.
There were also a few calls made using G2HR with which some good DX contacts took place to the Ukraine and a Brazilian island with the suffix ZX.
We also had an internet news report set up by Les.
From our new QTH at Friday Hall. Peter G4KSE and Michael 2E0MDQ tried to contact Tom M5AJK on the West coast of Wales, on consecutive club nights. Although Tom heard them, Michael and Peter could not hear Tom.
This goes to show how urgently we need to erect some good Antenna's at Friday hall.
So please contact Tom or Peter to see if YOU can help by joining the work party to erect these new antenna’s.
ROY G0PRK.
Secretary’s Comments
By G0DPT
A few weeks ago I bumped into a friend in the street I hadn't seen in a very long time. He asked me how things were, and in time the discussion turned to hobbies. He seemed surprised I was still interested in amateur radio; after all, in this modern era of communication by mobile 'phone to anyone and anywhere on the planet, what was the attraction?
I expect to someone with no connection with the hobby it might sound irrelevant in today's world; but the simple fact is amateur radio is alive and well, and has been quietly evolving with new technology. Amateur radio is also being integrated with other hobbies, often benefitting both at the same time. An obvious example is SOTA (Summits On The Air), where the miniaturisation of radio equipment, improvements in battery technology and lightweight beam antennas which collapse into a small bundle, enable the connection between hill walking and radio.
I have recently seen a recumbent tricycle pass me on the local roads fitted with a small 2M transceiver, and I know people who go fishing that always carry a portable transceiver with headphones, so they can listen to the HF bands.
New ways of communicating have never replaced amateur radio either, they have just become integrated; computers, satellites and television transmission were adopted relatively quickly by the amateur community.
As modern 'phones have evolved to do much more than their original purpose and are no longer hard wired into houses, the same has happened with amateur radio. Modern communication on the move is something most people take for granted, and it sits very nicely alongside amateur radio which has taken its own path, and is as relevant today as it has ever been.
Malcolm G0DPT
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My QRP Experiences...
By 2E0MDQ
After reading an article in Practical wireless I decided to see if I could run a quad loop around my shack walls as close to the ceiling as possible. I tried using some old cable TV coax which I believed was 75ohms. I had some clips and tried a couple to see if it would hold the cable without having to put to many holes in my walls. This method was not very good and I soon aborted it to try using some old mini-trunking which had a sticky back that I could stick to the wall instead. I cut small strips of this off and tried a couple on the wall, the first two worked and it seemed as though I had found a solution, I tried to get the plastic off the next few strips and just could not get it to come off without pulling all the stick off with it. After three attempts I decided I was just wasting my time and that it was probably an omen telling me I needed to go up in the loft.
So I took heed, taking the 11 metre length of coax up into the loft and used the clips to secure it to the rafters. This didn’t take that long as my loft space is just that, a space and working up there was fairly easy. The centre feed point for the quad loop was nearest the apex of the roof. The reason I mention this is because from what I can gather from some of the books I have read this is of some importance. As I was experimenting I decided to go with what I had done and attached about 10m of 50 ohm RG59 feeder to the quad loop outer shield using 30A plastic connector block, the excess I coiled up and cable tied it together to act as a choke balun at the rig end.
The formulas for quad loops are as follows;
(1005/frequency MHz) x 0.10 = length in feet
(306.4/frequency MHz) x 0.95 = length in metres
The 0.10 and 0.95 I believe are taking factors like free space and wire diameter into consideration.
The length of the wire I had cut was obtained from measuring the size of the shack 2.62m x 2.58m
Then using the metres formula I calculated which band the wire should be resonant on, if any. So after a few calculations I found that my wire would probably work on the 10m band
(306.4/28MHz) x 0.95 = 10.395m
I went back down into the shack it was getting late, it was 4.55pm and I kept trying until about 6.45pm. I connected up the antenna through the ATU and switched the PSU and then the rig on. Even though I knew I probably would not hear anything on top band 160m I still gave it a go. As I had predicted not much doing so I tuned to 80m, this time having some success on 3.750 MHz, I could make out voice through the noise but it wasn’t good enough to be really decipherable, however I was getting quite strong morse stations coming through and using an application called “CW Get” which can be found here at http://www.dxsoft.com/
I used this to decode a transmission sent by F9TMK a French station which I was receiving about 5/8.
The encounters were brief and tuning through the rest of the bands right down to 6m didn’t prove very eventful, I think maybe because conditions were so bad I could not rule this out even though the loop hadn’t been designed for these lower bands. I have read that it is best not to use an antenna on bands lower than the lowest band it was designed for. So I will have another go with it in the morning.
Its 9.03am and I started on 15m receiving strong morse stations on 21.008 MHz . At 9.20am I heard my first voice station UY5ZZ on 21.279 MHz a Ukrainian station. I was receiving him at 5/7. I listened on 20m and 40m hearing many more stations both voice and Morse. Then at around 9.55am I was listening on 7.055 MHz I heard a station speaking in English and I listened more closely as I tried to lock in on the signal. I had stumbled on a net which they said they had regularly on that frequency. I thought it may have been my quad but the stations were complaining of how bad conditions were and even they were having difficulty hearing each other through the noise. The stations I could actually hear were as follows; G7ESM, I think his name was Howard, I heard an Irish sounding guy but I couldn’t get his full call sign or name G0BI? He seemed as though he was driving the net, I could hear him well enough to confirm some of the call signs I got. I heard MW0CU? –Les but I could barely hear him and not for long as he kept going down into the noise M0CLU, and last and only just was G4UDO.
I was really very surprised that I had been able to
pick up English transmissions and I needed to check the call signs but straight away I knew that MW is the start of a Welsh call sign albeit he may not have been working from his QTH. It would be interesting to see where the other stations were based, as everything I seemed to be able to pick up came from the other direction, more into Kent and out into Europe as can be seen from the blue & red pins on the map below.
It started to make me think of the radiation pattern I was sending from the antennas I had used. I queried this with Leslie G0CIB and he helped to make it a little clearer, although I still needed to do more investigation as I felt it was a very important aspect that needed to be understood.
I was in the zone and decided that I would try and put the fan dipole idea to use. I had bought 10m of 2.5mm twin & earth from the club junk sale some weeks earlier. I stripped the PVC insulation using the earth wire to reveal the other two 10m cables inside. The rafters were approx 5m lengths which would give me a 10m inverted V dipole. (The shape of the roof) So using the formula for dipole length in metres I worked out which frequency this might work on.
Using the centre of the 40m band i.e. 7.1 MHz)
142.65 / 7.100 MHz = 20.09m = ½ wavelength.
Divide 20.09 by 2 = 10.04m each leg of dipole
Using the centre of the 20m band i.e. 14.175 MHz
142.65 / 14.175 MHz = 10.06m = ½ wavelength.
Divide 10.06 by 2 = 5.03m each leg of dipole.
So the inverted V dipole should work on 20m band and higher with the help of the antenna tuning unit (ATU). I still had a 10m length of 2.5mm wire and worked out that for the 12m band I needed a length of 5.720m which made two legs of 2.860m.
The last bit of cable was long enough to make a dipole also for 6m band which needed two legs cut at 1.399m
I decided to put these dipoles on the opposite roof face to the quad loop. Clipped to the rafters and at this stage I did not use an insulated block to connect all of the dipoles together as with the fan dipole configuration.
So I now have;
1 x ½ wave inverted V dipole cut for 20 metre band.
2 x ½ wave dipoles cut for 12 and 6 metre bands.
1 x 11m quad loop cut for 10 metre band
I connected the quad and went back down into the shack, and connected the antenna up to the ATU and the rig. Switched on the PSU and the rig and hey presto, I tuned straight away to the 10m band the first thing I noticed was how quite the noise seemed compared to the previous day. I played around with the ATU to see if the signal could be improved and noticed that I could actually improve it. I didn’t hear much on 10m, not sure if this was because of the time of day or whether my quad loop was ineffective, so I tried a higher band 15m and almost immediately started to hear Morse stations coming though. It was getting late and I had my fill so decided to call it a day. I was already looking forward to Saturday.
Michael 2E0MDQ
The Future Of Our Hobby
By G8VZD
Whereas the rapid development of radio and communications has been really exciting, our hobby does appear to have lost its buzz, although the decline is not universal it would seem.
So what can we do to defend it and put the fun back in?
What are the obstacles and what does work?
The appeal of amateur radio.
I will list the obstacles next month, but let’s first think of where the fun is and what brought us into the hobby. I dislike false optimism, that denies the problems. But defeatism is always right, because if you believe you are doomed to fail, that efforts are futile then fail you will.
For me the intro to our hobby was through the enjoyment of listening to broadcast radio. A neighbour threw away an old valve set which had a number of shortwave bands.
I enjoyed hearing Voice of America and “strange” Arabian stations with high pitched weird music and chants - this was 1962 after all..
A friend listened to Radio Netherlands and had a book showing how to get the optimum aerial length. It also touched on dipoles versus long wire aerials and the effect of aerial height. This was simple stuff an eleven or twelve year old could understand.
From that I started receiving post from Canada, Australia and more obscure places giving radio schedules and bands. My small country town world had just got bigger and more exciting.
I found I could rig up a bedside light to read, by using a link from the radio dial lamp.
Much to my parents horror I later rigged up a mains bedside light using twisted bits of non-insulated wire from the ceiling light !
It was time for me to start learning about electrics and safety.
A Christmas Gift of a Magnet Tricity set, was swiftly followed by the building of Crystal radio sets. An interest in model railways helped. Older encyclopaedias and books showed how to build first a two pole and then three pole motor using 6 inch nails and a cotton reel. It also explained how to wind the coils.
I went on to build a crude sound by light system using a photo transistor receiver and the output of the loudspeaker extension socket to power an ordinary cycle lamp bulb. Music was transmitted across the loft.
The light receiver was soldered using hard solder and a plumbers soldering iron heated on the electric stove, or a home wound coil was held in place by putty, but it worked
Plans to use lenses and tubes to focus light and transmit over a distance never materialised. We were kids acting alone. Dads were, a maintenance bricklayer and a foundry mould maker, not engineers or scientists.
My study of Amateur Radio was guided by the RSGB Examination Manual, a hardback book Foundations Of Wireless and Electronics by Mr MG Scroggie BSc and Radio and TV Constructor magazine.
I was self-taught and could not put the books down. I quickly grasped the role of series and parallel tuned circuits in IF stages. Luckily studies aligned with GCE O Level.
I was a poor constructor but It Was Fun.
Other interests, home brewing and the usual problems of being a 17 year old badly lacking experience and confidence took over.
I could not afford a set to go on the air, but what a lucky thing I had chosen Amateur Radio as a hobby.
I had failed at A Level but continued with evening studies in City and Guilds and BTEC as a Radio and TV Technician and these eventually helped me find good employment. But more, it allowed me to enjoy the fun of seeing and understanding developments and sometimes being at the forefront.
Just think how communication developments have completely transformed our world. It is hard for young people to understand just how different things were before.
The effect is as great as that of the arrival of Rock and Roll, Birth Control, Space Travel, Model T Ford, the Hippy Age of Aquarius and the Summer of Love and Package Holidays with cheap flights. People were now open to new ideas and were more aware of the world.
In the past it was only the upper class who were able to afford to travel that had the wider view of the world. Working Class life was local and in rural areas some people never left the village.
Now-a-days young people can play Monopoly with friends on three continents and families are held together by Skype or Yahoo video calls.
In the past it was only the trawler men who had contact with their wives by a.m. radio on 160 metres while far away at sea
Even beyond that, now on Freeview people can easily listen to Al Jazeera, Russia Today and 5USA.
There is an application for Android Tablets and phones called Tune In Radio which allows me to enjoy WCCQ a Country Music Station from Chicago.
Somali, Turkish and Filipino people in my area watch TV in their own languages from their home countries inside their local community café.
Broadcast radio has widened in some ways too. The less than liberal Voice of Africa Radio 94 FM, and London Greek Radio LGR 103.3 stations are available on FM and I enjoy listening to Kismet Radio 1035 or to Club Asia 963/972 on medium wave.
I do miss the days of Family Favourites when we maintained contact with people in remote
places on British Forces Posts Overseas (BFPO) though.
In some ways the war time and post war generation were better travelled than people today who only visit tourist spots.
The early analogue Sky allowed access to a program broadcasting images from the Space Shuttle and International Station called Space night, showing images over the different continents sometimes aligned to the music of that country.
The mobile phone and internet have enabled people in isolated places to trade more easily and fairly. The Trevor Baylis production of the wind up radio has brought outside contact to remote places and I am told that some Non Government Organisations have arrangements for repairing the wind up mechanism as well as the radio if ever it goes wrong.
So why is it then, that in an age of such excitement, our hobby sometimes lacks a buzz? And furthermore to quote
Nikolai Chernyshevsky “What Is To Be Done” to change things?
That is the next article!
Clive G8VZD
Four Element 2m Antenna
By G0CIB
During the Practical wireless QRP contest it was decided that the halo antenna should be replaced with something a bit better. The question then what was on the market, very lightweight, easy to put together and at a budget price?
In short I did not want it to be a backbreaker and would not have minded in the slightest if it got the odd dent in transit. So after looking on the internet and to be honest balking at some of the asking prices I came across a four element 2 meter antenna
(YGC-2C) from Moonraker via e bay at the total cost including postage & packing of just under thirty five pounds.
The antenna came packed in a long cardboard box with mast bracket and instructions. As with yagis the longest element is at the back and the shortest at the front. With this in mind it was assembled in less than five minutes very easily with minimal tools. After which it was checked with the instructions as is the usually practice ! The centre of the coax lead (not supplied) was connected to the adjustable capacitor terminal and the coax outer braid to the brass terminal. My own personnel preference was to cover the terminals with a large blob of electrical liquid tape to prevent ingress of water.
Ok so the big question is does it work ?
So after a trundle up the local high point i.e. pole hill in Chingford it was temporarily fixed to a five meter portable mast. Yes it did but the activity on 2m sideband has certainly declined since the eighties with just the odd rag chew heard. It will certainly do the job but I will have to wait till the next Practical wireless VHF QRP contest to put it through its paces properly.
Manufacturers specification:
Type : Yagi
Frequency TX 144- 146 MHz
Gain 7.0 dBd
Power 200W
VSWR : 1.5: 1 or better
Connection : direct
Boom length : 120 cm
Longest element : 92 cm
Mast size : 1-2 inch.
As supplied with mast bracket not shown:
Assembled
Terminal Box
Leslie G0CIB
Contests
144MHz UKAC VHF Contest 3rd Sept 1900-2130 UTC
RSGB SSB Field Day 7th-8th Sept 1300-1300 UTC
144MHz Trophy Contest7th-8th Sept 1400-1400 UTC
RSGB 80m Sprint Contest SSB 19-20.00 UTC 11th
September and 24th October
RSGB 21/28MHz Contest 6th Oct 7-1900 UTC
RSGB Club Calls Contest 1.8MHz 9th Nov 2000-2300 UTC
If anyone is interested in participating in any special events or contests please make this known at the Friday evening meetings
Why not organise a team. Operation from the Silverthorn shack is available at most times or go portable. The Club equipment is usually available if needed.
Is anyone up for one of the more unusual contests this year?
If so please contact me to see if we can get a team together.
Tom
M5AJK
Diary Dates
Club Events This list supersedes all previous ones. Please note these events are subject to change and other events will be added as they are organised.
Future events in 2013
Jamboree on the Air 19/20th Oct 2013
Annual General Meeting 25th Oct 2013 8.00pm.
Local Rallies 2013
Don’t miss these rallies… Check details with the organiser before making the journey
7 SEPTEMBER
UNIVERSITY OF GREENWICH ANNUAL CONFERENCE AND FORUM FOR THE UK AMATEUR HIGH ALTITUDE BALLOONING COMMUNITY-Talks, workshops and discussion. Tickets and info at http://ukhas.org.uk/general:ukhasconference2013.
27 & 28 SEPTEMBER
NATIONAL HAMFEST - RSGB in association with the Lincoln Short Wave Club.
Newark and Notts Showground, Newark. www.nationalhamfest.org.uk
11-13 OCTOBER RSGB CONVENTION – The full convention programme of lectures for all interests will be available on the website later in the year. Principal sponsor Martin Lynch & Sons. [www.rsgbevents.org/]
Near Milton Keynes. www.rsgb.org/rsgbconvention
10 NOVEMBER NEW DATE
WEST LONDON RADIO & ELECTRONICS SHOW (Kempton Rally) – Kempton Park Racecourse, Staines Road East, Sunbury on Thames, TW16 5AQ. TI, free CP, OT 9.50/10am. TS, FM, B&B, SIG, C, DF, WIN, LEC. Paul, M0CJX, 08451 650 351, info@radiofairs.co.uk. www.radiofairs.co.uk.