SOUTH DORSET RADIO SOCIETY
CATSWHISKER NOVEMBER 2001
The newsletter of the South Dorset Radio Society
Posted 25/10/01
Editorial
Hello and welcome to yet another month in the busy life of all you radio amateurs!
At last months meeting the members present appointed a new treasurer, following the resignation of Emma Illsley. On behalf of you, the members, I would like to thank Emma for all the work she put in during the time she was treasurer. It can be a hard and unrewarding job at times.
Our new treasurer is John Rose M0BQO m0bqo@g3sds.org.uk
All future subscriptions etc. should be sent to John please.
Carol & Robert our chairman have just had a short holiday and I am pleased to report that Carol is making steady progress on the road to recovery.
All those that attended last months meeting were given an insight into how Tim Walford’s kits were developed and the whole teaching and learning aspect behind each one.
Looking forward: Bargains galore in store at our annual auction and tabletop sale on the 6th of November.
Christmas lunch: To be held at The Glenburn Hotel on the 16th of December 12:30 for 1pm. We have an invited guest who I know you will be delighted to meet.
Booking are still being taken………………………
If you have any ideas for speakers or club visits for next year, please contact any member of the committee and they will pass it on for discussion. I remember going to Dorchester Brewery with the SDRS some years ago!!! How about something like that ?
Neville M5NEV m5nev@g3sds.org.uk
NOVEMBER 6th
SOUTH DORSET RADIO SOCIETY - TABLE TOP SALE AND AUCTION
Doors open 7pm
Sale starts 7:30pm with the Auction starting at 8:00pm
Unbelievable Quality BARGANS and Useful Junk!
All a builders paradise !
Bring along your unwanted items for auction or to sell at one of our tables. If you have a quality item for the auction and want it circulated to other clubs please give me all the details ASAP.
Coffee & cakes available - Come early to avoid disappointment!
Grateful thanks to M B Freight for the printing of this newsletter.
At our last meeting we were entertained with a talk and demonstration by Tim Walford of Walford Electronics. It was a most enjoyable and interesting evening. I think I can speak for everyone there when I say that amongst the kits on show was something for everyone to have a go at when building their own radio equipment.Below I have added a list of the kits that Tim has to offer and a brief introduction from him as to their content and usefulness.
Our aim is to provide instructive, fun-to-build kits, which perform well for whatever you decide to spend. There are a wide range of designs offering reduced size, lower prices, increased performance with something for most levels of construction skill. The circuitry is what really matters in these kits - as it is the largest part of the price, they provide excellent value for money. The kits are complete and their simple mechanics can be easily enhanced if you wish. The range starts with the very simple Chedzoy and progresses to the 'flagship' Bristol.. You can:- Find a project by category - Simple, Intermediate, Advanced or Accessories. Look at the complete list of kits giving brief details.
Audio sig gen - Source of pure two fixed tones or variable frequency single tone.
Booster Linear - 20 Watt amp 20 - 160m, 10 dB receive amplifier.
Bristol - Multi-band SSB and CW 5W TCVR, to 10m by plug-in cards.
Chedzoy - Regenerative TRF RX, MW and 80m or BC near 4 MHz.
CW filter - Adjustable RX filter and keyed oscillator for phone TCVR.
Counters - Frequency readout, Versatile 3 digit or 5 digit.
Chinnock - RX Direct conversion RX for 20 and 80m.
Chinnock - TX 'Crytsal' controlled CW transmitter for 20 & 80m.
Kenton - Matching single band CW transmitter to go with Midney RX.
Langport - 5 Watt CW and SSB transceiver for 20 and 80m.
Lowpass filter - Any two bands 6 -160m selected by relay.
Meter kit Adds - AGC, S/Pout meter and TX matching bridge.
Midney - Simple single band superhet RX for any band to 20m.
Minehead - 5 Watt CW DC transceiver, any band 20 -160m.
Porlock - 5 Watt Transverter for 6m from 20m base rig.
Priddy - DC receiver for 20, 40 and 80m. Matching TX is Godney.
Signal generator - Simple signal source covering 400 KHz to 50 MHz.
Speech processor - Boosts average signal level under difficult conditions.
Taunton - Multi-band phone tranceiver by plug in cards, 15 - 160m.
Recent accessory additions include a Speech Processor and Audio signal generator. The speech processor helps improve readability under difficult conditions. The Audio siggen provides either a single variable frequency tone or the fixed two tones needed for setting up an SSB transmitter.
For more information phone: 01458 241224
Look Out - Will 101 Dead Cats Return?
On the inside back page of the August 2001 Catswhisker, your editor asked," Do you know of someone who has invented something out of the ordinary? If so why not drop me a line’. That reminded me of the time when someone with a macabre sense of humour lent me a book titled ‘101 Uses for dead cats’. The idea was that if you got hold of them before rigor mortis sets in, you could shape them to make many useful things like a back scratcher or a soap holder for the bath etc.
I used the book title to head several articles that appeared in Catswhisker about things I had made from metal fencing panel brackets. These were a pcb holder, a ‘handy’ bracket and a soldering iron stand’. One that did not appear in print was a pan and tilt head for a tripod!
It is immaterial what you use. A chromium plated Edwardian dustbin lid would make an ideal base for a standard lamp, photographic light or microphone stand.
My current project is to convert a tiny hand held battery powered vacuum cleaner into a jet engine, but whatever turns you on!
So come on you lot, why not join my Dead Cats Society (current membership just me) and give your editor a break by sending him articles about your wonderful inventions.
There is a keystone to every arch; and a combination to every lock.
A Conundrum!
Our old TV had been giving trouble because of a faulty on / off switch. I decided on self help, but what to do for a switch. The old one was a double pole push type and I proposed to use a toggle switch.
I failed to buy one on a Saturday afternoon - so rang G0NEV but he could not find one at the shop. Ring the other club NEV call sign recently acquired by your editor - so I did and his shack produced a boxful from which a suitable one was selected and quickly fitted after boring a whacking great hole in a front panel.
It seems to work OK, BUT the conundrum is that a small resistor is soldered across the positive side of the switch - presumably intended as a surge limiter. But how does it work? When it is switched on it is shorted out, so what can it possibly do unless the original push switch operated to close the neutral line a fraction of a second before the live, thus briefly passing a limited current.
Can anyone tell me if I am right please, because if my conclusion is correct I could be letting myself in for more serious trouble substituting a standard toggle switch.
Anything can be made to work if you fiddle with it long enough.
73 de John G7BRU
A free service to members!
Yes, if you are on the Internet and want a personalised E-mail address, then drop Geoff Watts a line and he will give you an E-mail address with your own callsign.
All the committee members have their E-mail address’s as their callsigns.
Robert G0RYL is g0ryl@g3sds.org.uk
John M0BQO is m0bqo@g3sds.org.uk
Pat G1XJH is g1xjh@g3sds.org.uk
Richard M5RIC is m5ric@g3sds.org.uk
Neville M5NEV is m5nev@g3sds.org.uk
So you see it’s as easy as that, drop Geoff a line and he will do the rest.
That’s Geoff, G0EVW g0evw@g3sds.org.uk
Inventors Radiate Radio Through the
World
By the end of the 1800s, America and the world had been introduced to two revolutionary communications technologies-first Morse's telegraph and then Bell's telephone. What could be next? Scientists in Europe and the United States began working toward a wireless telegraph-moving toward technologies that would allow signal transmission without wire and instead use electromagnetic waves to link receivers and transmitters.
By the 1870s. British professor James Clerk Maxwell had mathematically proved that electric waves could be sent over distance. After Maxwell's studies, one German scientist set out to prove Maxwell's theories. In experiments that transmitted waves over a five foot distance, Heinrich Heine proved that waves travel in a straight line across space and that they can be reflected. Radio was born. As the 19th century concluded, an Italian physicist set out, continuing his colleagues work in radio's development.
Marconi's Wireless Telegraph Born in 1874 in Bologna, Italy, Gugliemo
Marconi is credited as radio's inventor, who developed what was then called
wireless telegraphy. In 1896, Marconi created what amounted to an antenna
to send and receive signals, and within a few years, he transmitted signals
across the English Channel and eventually across the Atlantic in 1901. Marconi
sent Morse signals over a record distance of 2,000 miles, but in spite of
his success, many in and outside the scientific community were quite skeptical
of Marconi's invention. How would the wireless telegraph impact life, they
wondered.
Marconi soon formed the American Marconi Company and equipped two American ships at sea to report live World Cup results to newspaper companies in New York. Radio's communication capacities were being felt, and in 1900, Marconi secured an American patent for his invention allowing multiple stations to transmit radio signals at different wavelengths.
Apparently, The Supreme Court ruled on June 21, 1943 in Marconi Wireless T. Co. of America v. U.S., 320 U.S. 1 that Marconi invented nothing that was not already covered in patents by Tesla, Lodge, and Stone. This contradicts the sources at the end of this article.
(Source for case citation: Kelly D. Motichek )
Deforest and the Audion Tube
As early as age 13, Lee DeForest was busy inventing a miniature blast furnace and locomotive train. His father urged him to become a Congregationalist minister, but instead, DeForest headed to Yale, where he earned his PhD in physics in 1899. DeForest later established his reputation as an inventor for his development of radio technologies with the Audion tube.
Completed in 1906, the Audion tube impacted broadcast technologies that emerged throughout the century by allowing live radio broadcasting, improving radio signals' amplification and enhancing signal reception. During the Audion tube's development, DeForest founded the DeForest Wireless Telegraph Co. but encountered serious problems with business partners. The inventor formed a second company-the DeForest Radio Telephone Co. And in 1910, he broadcast a performance at the Metropolitan Opera live from New York City on radio. (click here to see an original ad for the DeForest Tube. 64k Image)
Like his earlier radio counterpart Marconi, DeForest faced an uphill battle to convince his critics that radio was indeed a credible invention. In 1912, DeForest was indicted for mail fraud for his promotion of the "worthless device" called the Audion tube. DeForest sold most of his patents to major corporations for continued development. Today, Lee DeForest remains known as the "father of radio."
Radio Takes Off With Armstrong's FM Waves Just like any other new technology, radio continued to grow with the ingenuity of individuals who refined initial inventions. Edwin Armstrong improved radio's reception and amplification. His regenerative circuit developed in 1912 improved radio amplification, working from DeForest's Audion tube. Armstong's invention improved amplification by up to 1,000 times.
Armstrong later eliminated unnecessary static that accompanies AM radio by inventing FM radio. Instead of varying the power or amplitude of radio waves, Armstrong's FM radio transmission varied the number of waves per second. After his 1933 invention, Armstrong worked hard to convince people of his latest invention's credibility. He eventually invested $300,000 of his own money in an FM radio station, and today, FM radio is the norm. Throughout his career, Armstrong worked closely with the Radio Corporation of America (RCA) and received the highly esteemed Franklin Medal for his work around the regenerative cicuit.
The Kenya Project
PART 3
Having visited several "developing world" countries over the years, I have been confronted with many well-intentioned projects from the developed world. Unfortunately, those projects of a mechanical nature had an abnormally high failure rate.
Typically, one-off projects installed by well-meaning private associations from the West were let down by the lack of routine maintenance training to the recipients. I came across many instances of water supply systems not working due to a broken mechanical (or electrical) water pump or a simple plumbing problem, which could have been fixed by any one of us with the normal tools found in a domestic toolbox. In many instances I was able to effect running repairs using an emergency electrical tool kit that I carry with me which cost a £1 at ‘Poundland’!
Learning from these experiences, I was determined that the solar energy project should run on the fail-safe principle, with the minimum amount of possible operator intervention and error. I had established from the manufacturers that solar panels, in almost every scenario, fail open circuit, so connecting panels in parallel was not a problem as such (only the loss of available power from the failed panel). However, I wanted a means of easily checking that each panel was performing (or otherwise). Initially, my plan was for each panel to have a voltmeter wired across its output. Voltage and amperage output is directly related, so any reduced voltage would also indicate an amperage problem.
Enter stage left, Neville Bridle M5NEV, introduced to be by Dave M1OBR. "Come up and see Neville with me, Iain - you should see his place, he's got half of Winfrith in his workshop!!" So I took the long haul journey from Exmouth to Weymouth (to me it's the UK's worst road) and, upon arriving at Neville's, realised that Dave's statement was true! I might as well have been visiting Jodrell Bank!! After a short inspection of his (copious) amateur station, Neville thrust a large control panel into my hands, consisting of a brushed satin finished panel equipped with voltage meters, leds and miniature switching gear. A work of art, with beautifully fixed wiring looms on the reverse.
We all stood in his workshop ecstatically admiring the workmanship - so this is where all our taxpayers' money goes! Good job I brought my Sierra - I needed all the room to get the panel in! Then the horrendous journey home on the UK's worst road. A few days later, enter stage right veteran amateur G0GHO, Wilf of Exmouth.
I knew from my membership of Exmouth Amateur Radio Society that Wilf was a keen "project" constructor so enlisted his help. I proudly introduced the Winfrith Panel to Wilf who silently stood aghast before its magnificence. He scrutinised it with three different pairs of specs like an inquisitive doctor before exclaiming "So this is where all our taxpayers' money goes !!" I briefly outlined my intentions to him and we set about scribbling schematics on near-to-hand scraps of paper. It felt a little like being in the presence of Alex Issigonis.
Understanding the KISS (Keep It Simple, Stupid) principle I was planning, Wilf came up with a simple system of testing the voltage output of each panel individually, the technical aspect of which I left him to work on over the ensuing few days whilst I put my energies into how best to control the combined output and store the sun's free energy.
I hope I'm not boring you. Part 4 next month. Iain, M1OOO
Next Society Meeting
Tuesday November 6th - Tabletop Sale & Auction at the Chickerell Church Hall.
If you have anything you wish to be included in the auction please contact Neville M5NEV as soon as possible.
We have some wonderful quality items so far plus some old radios & some interesting bits and pieces!
A small commission will be charged for auctioned items if sold.
November 11th 2001 - The South Yorkshire Repeater Group presents the 11th Great Northern Hamfest at the Metrodome Leisure Complex, Queens Road, Barnsley, South Yorkshire. Doors open at 10:00 Trade stands, specialist interest groups and a large Bring & Buy. Talk-in on 145.550MHz . Morse tests on demand. More information on 01226 716339 or 07787 546515
November 18th 2001 - The Midland Amateur Radio Society (MARS) 12th Radio and Computer Rally. Doors open at 10:00. Free parking, trade and club stands and refreshments. For more information call Peter G6DRN on 01214 431189.
November 24th 2001 - The Rochdale & District Amateur Radio Society are holding their traditional radio rally at St. Vincent de Paul Catholic Church Hall, Caldershaw Road, off the A680 Edenfield Road, approx two miles west of Rochdale, follow the orange arrows from M62, J20. Yes, this is a Saturday rally! Open from 1015/1030, there will be a talk in on S22, Bring & Buy, refreshments, etc. More information from John G7OAI on 01706 376204
November 25th 2001 - The Bishop Auckland Radio Amateurs Club (BARAC) 2001 Rally at Spennymoor Leisure Centre. This venue is ideally suited for both trader and disabled as it boasts good parking and access to large ground floor hall. There will be the usual radio, computer, electronics and Bring & Buy stall, as well as catering and bar facilities. Morse tests will be available on demand. As you can imagine, there will be lots to do for all the family, within the confines of the Leisure Centre for those of the family not interested in radio. Doors open 1100 (1030 for disabled visitors), admission is £1, under 14s free of charge with adult. Talk-in on S22. Mark G0GFG on 01388 745353
November 25/26th 2001 - The London Amateur Radio & Computer Show takes place at the Lee Valley Leisure Centre, Picketts Lock lane, Edmonton, London N9. There will be trade stands, Bring & Buy, Morse tests, free car park, catering, licensed bar, talk-in, special interest groups, disabled facilities, camp site, and family attractions (including cinema, swimming, golf and spa).
Doors open 0945/1000. More information on 01923 893929.
CHRISTMAS LUNCH 2001
To be held at The Glenburn Hotel on the 16th of December 12:30 for 1:00 pm.
Contact any member of the committee ASAP to book your place @ £15.95 per head.
February 10th 2002 - The Harwell Amateur Radio Society are holding a Radio & Computing Rally at the Didcot Leisure Centre. This venue includes a large spacious hall, disabled facilities (including lift), bar, refreshments and good parking. Located three miles from the A34 between
Oxford and Newbury (signposted from A34).
Doors open 1030 until 1530. More details from Alan G8NVI on 01235 816379 or visit http://hamradio.harwell.com/
IMPORTANT NOTICE - Are you with us?
The South Dorset Radio Society and the South Dorset Repeater Group 2000 are separate entities.
SDRS is the Radio Club. Its annual subscription is £10-50.
SDRG 2000 is the Repeater Group. Its annual subscription is £10.00
Some amateurs do not appear to realise this, and may have paid a subscription to renew their membership of one of them, inadvertently overlooking that the other may need to be paid.
If you are in any doubt about where your membership stands, please take advice from the respective treasurers - John Rose M0BQO of SDRS (tel 832057), or Rob Mott G0ECX of SDRG 2000 robmott@supanet.com to verify whether your name is on the relevant list.
Members of SDRS should have a Membership Ticket dated some time in year 2001/2002.
Thanks - John Rose, M0BQO, Treasurer SDRS - m0bqo@g3sds.org.uk
Catswhisker Editor - Neville Bridle, M5NEV, 134 High Street, Wyke Regis,
Weymouth DT4 9NT - 01305 772806 m5nev@g3sds.org.uk
DEADLINE FOR NEXT MONTH IS 13th NOVEMBER
Please ensure that I receive your contributions before that date, 73 de Neville, M5NEV m5nev@g3sds.org.uk
(Full details of the Society and it's committee can be found on the SDRS Information page)