Tabla de contenidos para January 2024 en Practical Wireless

Practical Wireless Rating Well made, good value for money. In general terms there are three basic types of HF commercial mobile whips available on the amateur market: 1. Single-band whips covering just one amateur band. 2. A whip with taps on a loading coil, selected by a ‘flying lead’. 3. A whip with motor driven coil or separate auto ATU for multiband use. Let us look at each one in turn and consider what each one offers. The AmPro range of single band mobile whips comes into category 1. They have the advantage that each single whip is relatively inexpensive and is easy to tune. Once tuned and locked into place, it should hold its resonant frequency. These types of mobile whips are lightweight and can be secured to a…

This has to be one of my favourite radio events of the year: The meeting of the British Vintage Wireless Society (BVWS) took place, once again, in Golborne, on 29 October 2023. The old TV sets normally to be found there were missing this time around. However, there were plenty of beautiful antique and classic radios to behold, as well as sundry accessories, tubes, books, magazines, and much more to delight the heart of the vintage enthusiast. Having a chat with some BVWS members and stallholders here is always an enlightening experience and shows just how much interest there is in classic gear and collecting. The highlight of my visit was coming across a 1922 copy of Popular Wireless Weekly, with an article by Oliver Lodge in it, entitled For…

Having a portable antenna that can be used on various bands, as well as having a small footprint, is going to be one of the most challenging type of antennas to design or construct. One of my favourite antennas that meets this criterion is the Asymmetrical Hatted Vertical Dipole. As the name suggests it is a dipole antenna that is loaded by means of a capacity hat. The drawing, Fig. 1 shows the more common designs of an AHVDA. The one we are going to look at is design D. The design of this antenna means that we can assemble it using off-the-shelf parts, which is good for various reasons such as ease of assembly as well as replacing any parts in future. The first thing you need to purchase…

Welcome to the January HF Highlights and a very Happy New Year to all readers. On 9 November some of Bonaire’s radio amateurs got together for a dinner at one of the restaurants in downtown Kralendijk, Fig. 1. Paul PJ4SON has recently become active, mainly on 28MHz SSB, and Ish PJ4ISH is a new licensee who hopes to be active soon. There were so many DXpeditions during the month under review, from mid-October to mid-November, that there’s only space to give each the briefest of mentions. The month on the air When last month’s HF Highlights was ‘put to bed’ on 11 October there were eight DXpeditions on the air simultaneously. Yuris YL2GM operating as ZD9W from Tristan da Cunha was on the air from 29 September to 22 October…

The receiving instrument on the first successful Atlantic cable of 1858 was a sensitive mirror galvanometer. This detected variations in a very small current received through the cable. The variations moved a finely balanced needle combined with a mirror, to deflect a ray of light onto a screen. From these deflections one operator read off the signals and called them to a second operator who wrote them down in longhand. Later, a slightly better system was described by George B Prescott, in his History, Theory, and Practice of the Electric Telegraph, 1864: “The operator, who watched the reflection of the deflected needle in the mirror, had a key, communicating with a local instrument (a register) in the office, which he pressed down or raised, as the needle was deflected; and…

As far as I am aware VHF/UHF repeaters universally employ vertical polarisation. Most people interested in 40/50/70MHz are interested in sporadic E and use horizontally polarised beam antennas. I remain unconvinced about that for sporadic E. I do not think polarisation is important at 50MHz except to extend range when terrestrial propagation is required and there vertical polarisation is an advantage but an inconvenience for fixed stations. I have however already noted and published the likely, short term, alignments of the ionosphere in the wake of the electric fields in ‘thunder cells’. However, that is not the purpose of this article. The purpose is to provide a convenient vertically polarised antenna for local and occasional sporadic E communications. A utility antenna. Of low effort, expense and of good performance lending…

New from Moonraker The RIGEXPERT SHACKMASTER POWER 500 (36A) power supply features: Space-saving design with touch screen display • Lowacoustic noise • Multifunctional Touch Display • -30°C to +70°C operating temperature • Intelligent protection system • Prioritising safety and security, it features an advanced Intelligent Protection System. So your device is shielded from overcurrent, overvoltage, and overheating, allowing you to work confidently, knowing your valuable equipment is well-guarded. The ShackMaster Power 500 is equipped with four Powerpole DC connectors, offering ample ports to effortlessly connect various devices without the need for adapters or complex configurations. Also features two USB Type-A ports and two USB Type-C ports, it empowers you to charge devices, connect peripherals, or power USB-compatible gadgets seamlessly, all while maintaining a clutter-free workspace. It includes a built-in USB…

The radio telescope at Arecibo, Puerto Rico, was at one point not only one of the most iconic telescopes in the world, for many decades (completed in 1963) it was also the world’s largest single dish spherical telescope and the most sensitive. During recent times it’s been superseded by the FAST (Five Hundred metre Aperture Spherical Telescope) instrument located at Guizhou Province, China. There is another similar device under construction in Australia and South Africa, the Square Kilometre Array (SKA), which will, as its title suggests, be the largest radio telescope when it finally becomes operational. The Arecibo observatory, Fig. 1, was opened towards the end of 1963. It employed a 1000ft spherical reflector. Incoming radio signals would be focused on a movable antenna gantry positioned about 550ft above the…

It was a Friday morning in the electronics lab and Jeff was mulling over his plans for the weekend while making himself his usual early morning cup of tea when his apprentice Natalie approached him. “Morning Jeff”, she said, “I know we usually talk about electronics stuff on a Thursday lunchtime, but yesterday when we talked about capacitors, we didn’t have time to discuss how they work and that so I was wondering”. “If we can talk about them today”, Jeff cut in. “Yes, if we can”, Natalie replied. “OK, I suppose so”, said Jeff, “Let’s get it out of the way then”. Lunchtime arrived and Natalie wandered over to Jeff’s desk. “Right”, said Jeff, “Yesterday we looked at some of the physics behind electric fields and that and how…

Last month I started describing how I intended to plan my new antenna systems at my home QTH. With the retirement of my Scam 40 40ft pump-up mast I intended to replace it with a lighter and more manageable LMA-L 33ft Portable Mast, which I obtained from Moonraker. I also ordered a pair of TK-12 heavy duty mounting brackets and mast clamps for it. The LMA mast was to go back into the same position that was occupied by the Scam 40. This was against the house wall in a small corner where the garage attaches to the house. My first task was to clear an area of junk that had collected in the corner after the removal of the old mast. I then gave it a quick power wash…

Anumber of technical innovations were developed by BBC engineers especially for the 1953 Coronation. These included an improved version of the lip microphone, Fig. 1. This type of microphone was first developed for the 1937 Coronation so that commentators working in different languages, or on different networks, could be placed at intervals of no more than five feet apart without causing interference to each other. Other developments for the 1953 Coronation included: the derivative equaliser, which proved effective in compensating for certain types of electrical and optical distortion experienced with television cameras; a new method of camera synchronisation; the suppressed-frame process for recording television pictures on film; and the special equipment used for converting the television signals transmitted from this country to the different picture standards prevailing on the Continent.…

Send your letters to: Practical Wireless Letters, Warners Group Publications plc West Street, Bourne, Lincs PE10 9PH E-mail: practicalwireless@warnersgroup.co.uk Treacle tin dummy loads Dear Don, I guess making dummy loads into treacle tins was something done back in the day. I think mine (see photo) predate the ones in PW as the tins are marked 1lb and 2lb. Ian Jones G4MLW York More nostalgia Dear Don, I guess, not unlike a lot of other septuagenarians, I can never quite get enough of nostalgia in all its various shades. One shade of which is many things radio. But my constant regret in this regard, is waving goodbye to so much radio equipment that in the luxury of hindsight I wished I’d kept. But didn’t. There again, being pragmatic, it wouldn’t have…

My trusty Hermes Lite 2 transceiver serves me very well most of the time, but there are occasions when I could do with a little more than 5 watts of RF. Looking around the available options, I settled on the HARDROCK-50 PA. This is a very well-designed 50-watt, HF to 6m PA with automatic RF detection and simple manual/auto band switching that requires a drive power of up to 5 watts. The HARDROCK-50 is an ideal match for the Hermes Lite 2. The HARDROCK-50 is based on an original design by Jim Veatch WA2EUJ, first published in the August 2010 issue of QST magazine. Although the HARDROCK-50 is supplied as a kit, all the surface mount components were preinstalled. As a result, all I had to do was fit the…

Generally good weather, albeit with a rather cold northerly wind in part, greeted those who ventured out portable for the 15th Practical Wireless 70MHz Contest on Sunday 24 September 2023. The 23 entrants made a total of 400 contacts with 76 different stations in 15 different squares, Fig. 1. Low power section winner Wayne Dabrowski MW0LKX/P operated from IO82KL and won the low power section using a Yaesu FTdx10 transceiver and a 6-element PowAbeam antenna. Wayne showed the benefit of operating to the end of the contest by working OV3T in Denmark with just 10 minutes until the end of the contest, and was the only entrant to do so. Open section winner Gloucester Amateur Radio & Electronics Society G2HX/P were the winners of the high-power section. They used an…

There were two particular reasons I was keen to meet Martyn Baker G0GMB, the subject of this month’s feature. Firstly, I knew that he was an enthusiastic VHF DX-chaser and I was keen to learn more about his achievements despite the handicaps of a suburban location with limited antenna space and high local noise levels. And secondly, I knew that Martyn was one of the most familiar faces in the RSGB, with the important role of coordinating operations at the RSGB’s highly successful National Radio Centre at Bletchley Park. What, I wondered, was involved in bringing the magic of amateur radio to the thousands of visitors that GB3RS attracts each year? Martyn’s QTH is Stony Stratford, near Milton Keynes, famous in amateur radio terms as the birthplace of the world’s…

REVIEW SKYKING TXHF-6 – A VERY DIFFERENT DISCONE: Richard Constantine G3UGF says “You can never have too many antennas!” THE NEW SDRCONNECT SOFTWARE: A review by Georg Wiessala. PORTABLE MILITARY RADIO COMMUNICATIONS OF WWII: Graham Caldwell begins a series of articles on WWII portable military radio equipment, including their collecting potential. CONTROL THE CONTROLLER: Billy McFarland GM6DX has an Arduino-based project to control a Yaesu rotator from your PC. DATA MODES: Mike Richards G4WNC introduces the Hermes Lite 2 and explains how to get it up and running. TRANSMIT QUALITY AMONG MODERN TRANSCEIVERS, PART I: Frank Howell K4FMH starts a series looking at the transmit quality of the current range of commercial transceivers. There are all your other regular columns too, including HF Highlights, World of VHF, Antennas, Book Reviews,…