SILVERTHORN RADIO CLUB
GB2HR GX2HR GX3SRA GX8CSA
Spurious Comments
By M6MBM
March will be a busy time for the club, as we are moving venue to 56 Friday Hill, Intermediate exams are also planned for early this month.
I will be one of those hoping to soon have a 2E0XXX call sign and the chance to start working on the Full License.
National Mills day is almost on us again members are invited to show their support.
Guys, let’s ensure that we keep Spurious an interesting read by each of us writing an article on a regular basis. What we need is a report of your visit to a rally; your radio activity while at home or on holiday; special event stations you’re involved in; a description of your equipment;
It does not even have to be radio related if it is something you are passionate about and you will find easy to write many or even just a few paragraphs about. But whatever you send in please include some photographs.
Finally I would just like to say welcome to our newest student Nigel, who already is getting stuck in putting his electronic skills to good use diagnosing & mending the club HF rig. We hope that you enjoy your time here.
Michael M6MBM
Chairman’s Band
By G0PRK
Welcome to the March edition of Spurious 2013.
First big job of the year is the move to
56 Friday Hill. This is expected to happen during March. The licence to occupy is imminent.
We will need help with moving the kit, setting up the shack and sorting through our stores to sort out the wheat from the chaff, so as to ensure we take only good gear to the new QTH.
In addition there is work that is necessary to get the new building going.
The first task will be preparing the new site to enable us to rebuild a section of the Tom Oakman Centre as a temporary building at the rear of the site.
We will need lots of help with this as it’s not a job that can be done by two or three people alone.
So please We need folk to give generously of their time to help with this important project
Please contact Tom 07866636492. To find out how, where and when you can help
Come along everybody it's all hands to the pumps to move the club HQ to its new address.
ROY G0PRK.
Secretary’s Comments
By G0DPT
One of the topics raised at a recent club meeting was the influence of technology on portable operation. Having been interested in Amateur Radio since I was at school, it is one area I really have seen change before my eyes.
Talking to G2's and G3's back then, portable operation to the average amateur post-war up until the 1970s was a major undertaking, with provision of power supplies and generators for vastly heavy and fragile equipment that was temperamental at home much less on benches and large wooden tables in the open air!
In the mid 1980s, I thought how compact it was to be able to take a HF transceiver, ATU and long wire on a converted golf trolley with a car
battery, and be able to get a few hours of operating with equipment that fitted in the boot of a medium sized car.
Today with the introduction of the small pocket sized HF transceiver, it is possible to carry an entire shack in a fisherman's multi-pocket jacket, and there are a world of antennas designed for compact storage and rapid deployment, that enable a decent signal to be sent and received,
particularly so for VHF and above.
The speed at which technology is being introduced to the hobby is also increasing;
you no longer wonder what might be available in a decade, but only a few short years hence.
For many years the hobby evolved relatively
slowly and change was gradual.
Now the hobby is evolving quickly and we must not only embrace this change, but become part of the Amateur Radio movement that
shapes it.
Malcolm G0DPT
Bargains to be had!
Michael recommends.........
JAB Electronic Components for Radio Hams
http://www.jabdog.com/
We normally despatch items twice a week Mondays & Thursdays. We aim to complete all orders as soon as possible and in any case Within 14 days from receipt.
Rod recommends............
DIRECT ELECTRONICS
627 Romford Road
Manor Park E12
Tel: 020 8553 1174
RSGB Special Offers.
From their on-line catalogue
Some of the current special
Offers are web exclusives!
Buy today whilst these offers last!
When they are gone - they are gone! Or so I’m told!
Only available at www.rsgbshop.org
Basic fault finding in the field
By G0CIB
So there you are in the middle of nowhere, freezing to the bone, fingers turning blue, wet, hungry, teeth chatting and your trying to fault find on a communications system. STOP !
Let's just rewind a moment. How can anyone expect to function properly in such a situation without looking after themselves first?
None of that Ray Meers stuff surviving on twigs, nettles and bits of bark leaf. Why he does not got to Tesco's like normal people I will never know.
The first base should always be to a first class member of the “self preservation society” including of course protein, e numbers in fact anything resembling hot food. People can rough for a while, however after about three days they cease to be a useful cog in the wheels of society and end up as a total liability.
Anyway onwards with the purpose of this article “basic fault finding in the field”, what could cause faults and what type of faults could occur?
Causation of faults:
1. Human error: This covers a multitude of sins. The easiest and most common is not checking the equipment before even walking out of the gate. That’s right, check that it works!
Tug the coax & cables with a Marconi Mark, I finger tug test. If it comes apart fine, no problem, fix it properly. Better it goes wrong in the workshop than in the field. Check all the bits are there. It’s the easiest thing in the world when putting together a station to forget that vital small link or cable which as a result of missing it the whole station will not work.
Human error also includes the competence of the operator on the equipment being used, understanding what all the switches do. You all know the scenario, a single switch in the wrong position. Blank looks all round as to
why the equipment is not working. A real “Homer Simpson” moment. It does happen! Others things can come into the equation such as fatigue, lack of experience, lack of knowledge (who ever reads the manual), unfamiliarity, attitude and time constraints.
One of the first things that I do when visiting a new site is put the kettle on and make a large mug of coffee ! Firstly that checks the availability of the power supply and secondly it gives me time to slow down for ten minutes or so and assess the site properly, work out what I am going to do and not rush around. Time spent doing this prevents problems later.
2. Mechanical failure: These are self evident by inspection, however they do sometimes overlap with electrical faults. For example if a cable anchorage failed. This may have contributed in turn to electrical connections failing.
3. Electrical failure: This type of very common fault is to do with cables and there connections. I always carry a few spare in the kit bag. Spare fuses are tapped to the supply cords. You have simply not got the time, effort or inclination to carry loads of test equipment. Forget about oscilloscopes, time domain reflectometer and the such. The emphasis is very much on getting the station up and running as quickly as possible. The only piece of test equipment that I ever carry is located in my top pocket and is a small multimeter used for voltage and continuity tests. The major area of failure being headphones, handsets etc which are notorious for going wrong.
Types of fault:
1. Open circuit: These are normally indicated by something not happening when it should due to a broken conductor, or loose
connection. These type of faults can be found with either the use of a multimeter or the MK I eyeball !
2. Short circuit: These may be indicated by a burning smell detectable by the Mk II nose ! Fuses may be blown, circuit breakers may be tripped etc. Again having a good look may locate the area of the fault or if something needs replacing.
3. Earth fault: These are apparent by the circuit breaker tripping and are an indication of failure of insulation to earth or ingress of water. The key to this type of fault is to find out why the fault is occurring and not to take the circuit breaker out of line, which can cause even more damage or even injury ! Ingress of water is a problem but can be prevented. If there has been accidental ingress ensure that it is removed as soon as possible otherwise corrosion may develop, especially metal parts or cause contact problems in relays etc.
With fault finding nothing is worse than muddled thinking. There has to be a bit of logic behind it. For example going back to our station set up, if the power supply unit is not working then why on earth spend any time looking at other bits of kit? Does it matter if the power supply unit is a small battery pack or a large generator. No, the logic is the same. Get that part working first. Then work on the next box. Does it work, yes, then carry on. Has a fault re occurred? Oh, it must be something to do with the box or cable I just added. Can I substitute anything or take something out of line to show that is the part at fault? Can I get the station working without that box or cable and then carry on?
Once the transceiver appears to have power, lights on etc I tune the receiver to a known station. If I can receive it ok, then that gives me confidence that the receiver and antenna is working ok. I can then concentrate on the transmitter side. The question then is: does the transmitter load correctly into the dummy load?
In conclusion the key to fault finding in the field is all about trying to prevent faults occurring in the first place, proper maintenance of the equipment, attention to detail, checking it thoroughly before you go out the gate and understanding how the kit works. It is really all down to prior preparation and planning. And if it does go wrong understand the type of faults, why they occur and apply a logical approach to solving the problem. Eventually after time and experience you will be able to go directly to the fault and fix it straightway !
Leslie G0CIB
National Mills Weekend
By M5AJK
National Mills Weekend 2013 will be held on the weekend of 11th & 12th May this year.
The S.P.A.B. Mills section (Society for the Protection of Ancient Buildings) run this event every year on or around the second weekend in May, and Denby Dale Radio Society will again be co-ordinating this for amateur radio.
This event is not a contest, but an opportunity to set up a portable station in a novel location and contact similar stations around the country and beyond. Other Mills stations may be operating on any of the bands, so it will be a challenge on both HF and VHF to make those contacts.
As in recent years we hope to be able to set up at House Mill on Three Mills Island Bromley by Bow. House Mill is one of only three tidal mills in the country which adds interest to the event and gives us a little more to talk about on the air.
As the name suggests, there were once three mills on the island. The Clock Mill building still remains across the road from House Mill, but the third mill, a wind mill has long gone. House Mill was used to grind the grain for a distillery just across the canal from the mill. Unfortunately an incendiary landed on it during WWll and the distillery exploded due to the large quantity of gin stored there! The explosion also serious damaged House Mill such that it was put out of use and deteriorated over the decades.
In recent years the Miller’s House has been rebuilt using much of the old materials which were left in the rubble on the site. And now the mill is being refurbished though it will never have its twelve mill stones reinstated. It is hoped that the power of the water flowing beneath the mill will again be used but this time to produce electricity for 350 local homes.
If the mill is taking part in the SPAB National Mills Weekend again this year I hope that once again, Silverthorn will be running a station to promote awareness of the mill as well as amateur radio.
We have a QSL card which is based upon a post card which the mill had produced to publicise the reconstruction of the mill. It is only in monochrome and it would be an improvement if we could produce on in colour. So if there is a photographer amongst us who can take a decent
photograph of the mill, then that could form the basis of our new card.
Taking part in Mills on the Air is a great way to promote our hobby but it also helps to publicise the work done by SPAB in keeping alive our industrial heritage.
Silverthorn will only be at House Mill with the agreement of the mill and only on the Sunday as the Mill does not open on both days of the weekend. So we will have to maximise the time that we are on site.
The most important factor is the erection of the antennas in as short a time period as possible and planning how this is to be achieved is paramount. In each of the past two years we have not got this quite right, so we are hoping to do better this year. Our target is to be on the air by 10am.
Anyone who works 10 or more Mills on the Air stations during the weekend will be awarded a certificate if a minimum of £5.00 is sent as a donation to SPAB, together with your log, to Gerald G3SDY g3sdy@sky.com
The Netherlands are famous for their many windmills which were used to pump water from their dykes. They also join in with this weekend by bringing as many mills as they can to life with amateur radio. So why not put up a powerful Yagi and point it east then see what you can get on VHF?
Tom
M5AJK
The VFO Projects
By M6MBM
"The alternative VFO project was a real breath of fresh air. Everything about the build to me was just so much easier, so much so that I had it built and calibrated in a few sessions."
I had been searching for components for the original Intermediate course book project when I came across a link to the RSGB tutors page with an alternative VFO project. You can find it here at
http://www.rsgbdata.net/wp-site/booksextra/intermediate/an-alternative-intermediate-vfo.pdf
The opening paragraph had suggested that tutors had found problems with the project for one reason or the other, and that the "Alternative VFO Project" may be the way to go. So rather than waste time I decided that I would build both projects and have something to compare the original too. JABDOG Electronics prices for the additional kit were very reasonable, so I ordered both kits from JABDOG and received them within a couple of days.
In my opinion compared to the instructions for the original VFO project the alternative projects instructions were very clear and concise, a twelve page document with pictures to assist with the teaching process.
I must say this was such a joy to build, using the same sort of single sided copper clad PCB material and a similar assortment of components, I had the build completed in three sessions.
So with the build completed I connected up a 12v supply with the negative lead connected onto the PCB and the multi-meter connected in series to measure the current between the positive terminal on the PSU and the positive terminal on the PCB.
The instructions stated that I should be seeing around 45mA if all was well with the build. I was over the moon when It gave me a reading somewhere in the region of the desired figure.
This meant that I could now connect the PSU up correctly to the VFO and start checking to see if it was generating a signal
This time instead of 'ugly style' the method of construction used was 'Manhattan-style'. Copper side up for all ground connections, two strips of this material were cut and then stuck parallel to each other on top of the copper PCB. Once dry the strips were then divided into segments. This was achieved by cutting carefully through the top layer of copper thus creating an open circuit. These strips provided soldering points for non ground connections.
The as fitted drawing and the colour pictures made soldering the components a breeze.
As with the previous project I used the club HF rig to search for the VFO signal and it didn't take me long to tune into it. Double checking it was the VFO signal by placing my hand near to the VFO and moving it away causing the tone to change while I was doing so.
Then again as with the first project I had to calibrate the VFO to the 80m amateur band. I first had to find the frequency at each end of the VFO's range, basically with the trimmer fully open and then fully closed rotating the variable capacitor to obtain the minimum and maximum frequencies.
A note was made of these values.
The VFO was outside of the acceptable range 3.5MHz - 3.8MHz so I had to set the variable capacitor to its lowest range and set the trimmer until it came into spec and tested the range again. I had to do this a few times until it was satisfactory.
Finally I managed to get it into spec, and all without having to change the inductance with more or less coil windings or adding any more capacitors.
Happy days.
Michael M6MBM
Contests
A number of events are listed in the Diary page, but there are numerous competitions and non-competitive events throughout the year for anyone who wants to become more involved in their hobby. So have a look through the RADCOM pages or check on-line for coming events.
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.
March - Club moves to 54 Friday Hill
Future events in 2013
National Mills Weekend 11/12th May 2013
VHF National Field day 6/7th July 2013
Silverthorn Club Camp Jul 2013 Date to be determined
Jamboree on the Air 19/20th Oct 2013
Annual General Meeting 25th Oct 2013 8.00pm. Probably at New Venue
Local Rallies 2013
Don’t miss these rallies… Check details with the organiser before making the journey
3rd March - BRATS RAINHAM RADIO RALLY –
Rainham, Kent. Trevor, G6YLW, 07717 678 795, trev wig1.co.uk.
3rd MARCH - CAMBRIDGE & DISTRICT AMATEUR RADIO CLUB RALLY –
Godmanchester, Cambs. David M0ZEB, 01353 778093, rally2013@cdarc.co.uk. www.cdarc.co.uk
7th APRIL - CAMBRIDGESHIRE REPEATER GROUP RALLY –
Foxton, Cambridge. Lawrence, M0LCM, 01223 711840, rally2013 cambridgerepeaters.net
www.cambridgerepeaters.net
28 & 29 SEPTEMBER
NATIONAL HAMFEST - RSGB in association with the Lincoln Short Wave Club.
Newark and Notts Show ground, Newark. www.nationalhamfest.org.uk
12-14 OCTOBER RSGB CONVENTION –
Near Milton Keynes. www.rsgb.org/rsgbconvention