Tabla de contenidos para July 2023 en Practical Wireless

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g4owy6@gmail.com Just imagine amateur radio being commemorated on a British commemorative postage stamp. Wouldn’t that be amazing? Sounds fanciful? Not really, unlike the UK where the Royal Mail demurs to issue a commemorative stamp depicting amateur radio’s historic links with radio communications (preferring instead to promote the likes of Star Trek and Thomas the Tank Engine), many other more enlightened countries have long since abandoned that mentality, gifting amateur radio worldwide exposure on a commemorative stamp each time it’s stuck on an envelope or put in a stamp album. Countries with Amateur Radio Stamps Here then, is a small listing of those countries who have dared to buck the UK trend and issued amateur radio related stamps: USA, Pitcairn Islands, Greece, Norfolk Islands, Bhutan, United Nations, Ecuador, Israel, Spain, Columbia,…

gw4vxe@icloud.com On the afternoon of 23 April, the FM portion of the 2m band was really buzzing with activity. A series of nets around the country, co-ordinated by Tim Hughes G5TM attracted a great deal of activity, resulted in a lot of fun and some surprising contacts into the bargain. Tim co-ordinated 17 different net frequencies, run by volunteer stations generally in good locations on high ground. With the net control stations well located, many stations with simple setups were able to call into at least one of the nets and many to more than one. A number of the net controllers were able to work each other. Tim kindly put together a summary of the event. A total of 465 stations were logged and there were 587 check-ins to…

m1mwd@gmx.com To start with, I have a question. Are you a Prepper? Ehh…never heard of it? No really? As you saw recently, I’m just back from the Orlando Hamcation – a square mile or two of radio equipped RVs and campers. And nearly every one of them is home to a Prepper. No not a weird pet, but people getting ready for the Apocalypse, the end of times, a zombie revolution, or just the chaos of a world with no internet. This last seems strange to my ears. Was not the technology of the internet (datagrams, IP addressing, and routers) designed specifically to work around local or even regional breakdowns in the communications infrastructure? But I digress. My Big Idea The thing all those RV people have in common is…

practicalwireless@warnersgroup.co.uk I like to keep an eye on operating trends via PSK Reporter and have noticed that FT4 activity has been enjoying increased popularity of late. I also not iced I hadn’t covered FT4 for a while, so now is an excellent opportunity to put that right! As you can guess from the name, FT4 is very similar to and has been derived from the hugely popular FT8 mode. FT4 was originally designed with contesting in mind and is optimised to support high QSO rates. The most obvious change is the 7.5-second Tx/Rx cycle instead of the 15 seconds required by FT8. However, there are more changes under the bonnet, including 4-tone continuous phase frequency shift keying (CPFSK) and an increased bandwidth requirement of 1.6 times. The net result is…

practicalwireless@warnersgroup.co.uk At one time or another every radio amateur aspires to buy a matching speaker for their radio transceiver or receiver. Just about every amateur radio manufacturer has produced matching speakers for almost all their individual radios. And where they haven’t, an audio manufacturer has neatly stepped in to take advantage of this gap in the market. Matching or ‘companion’ speakers were pretty basic from the 1940s to the 1990s, most consisting of a single four to six inch (100mm to 150mm speaker) sometimes round but quite often elliptical in shape in an otherwise empty wood or steel box with a perforated grill over the speaker. And they weren’t cheap either – the matching MS-4 speaker for the Drake R-4 and TR-4 series cost around US$100 back in the 1960s.…

MAKESHIFT PSU: Billy McFarland GM6DX describes how to repurpose a PC power supply for amateur radio use. THE UMPP-1 MORSE PADDLE BY GM0EUL MORSE KEYS: Daimon Tilley G4USI reviews a small paddle key that offers great performance at a sensible price. QUANSHENG UV-K5 REVIEW: Keith Rawlings G4MIU reviews a bargain 2m/70cm handheld from China. VALVE & VINTAGE: Michael Jones GW7BBY/GB2MOP discusses the issues involved in working with AC/DC sets, using the Eddystone 840A as an example. TRIGGER WARNING, IT’S TRIGONOMETRY: Godfrey Manning G4GLM shows why trig matters. BUILDING AN UNUN FOR AN EFHW: Mike Dunstan G8GYW explains how to build your own UNUN for an end-fed half-wave antenna. There are all your other regular columns too, including HF Highlights, World of VHF, Antennas, Book Reviews, Vintage TV & Radio, What…

CDXC 2023 CONVENTION HEARS 3Y0J & 3B7M STORIES DIRECT FROM TEAM LEADERS: Saturday 13 May saw the CDXC (The UK DX Foundation) AGM take place at the Link Hotel in Loughborough, followed by an afternoon of presentations. The day started with a chance to catch up with old friends and make new acquaintances over a coffee while swapping stories of DX made and, in some cases, “the one that got away”. The formalities of the AGM followed and at the conclusion the topics of reaching DXCC Honor Roll and operating DXpeditions with a Rig in a Box approach were discussed. Both topics produced lively debate. The afternoon talks commenced with one of the most waited for DXpeditions in recent years 3Y0J. CDXC were the first UK group to have this…

dk8ok@gmx.net Small as it is, the IC-705 continues to represent the biggest innovation in the market for industrial amateur radio transceivers since its introduction in 2020. With this transceiver, Icom has consistently combined excellent receive and transmit data [1] with modern interfaces such as USB, WLAN and Bluetooth, while at the same time keeping its dimensions and weight low – even with a Li-ion battery attached! – in an exemplary manner. But it only delivers 10 watts? “If the transmitting power were generally limited to 30 watts”, wrote the British antenna expert (Antennas for all Locations, RSGB) L A Moxon G6XN, as early as 1982, “probably little would be lost, but much would be gained”. And at that time, the rise of digimodes, which were to see the light of…

practicalwireless@warnersgroup.co.uk As a teenage Short-Wave Listener, I had never heard of a voltage standing wave ratio (VSWR) meter. I don’t recall the amateurs I visited having such devices. Most of them seemed to tune their ex-Lancaster bomber or various other ex-war department and semi-lethal homebrew transmitters for maximum anode current flowing through the final power amplifier (PA) valve. The aim, to feed maximum RF to mainly random length wire antennas or open-wire doublets. Ex-government thermocouple ammeters were commonplace Others used lashup RF sense field strength meters, either in the shack or remote at the bottom of the garden. How far we’ve come from those heady days. While the hand drawing of a full circuit diagram of a transmitter with component values featured in my RAE exam and much practised in…

g4fai@btinternet.com In late 1944-early 1945, as the Allied armies closed in on the enemy homeland, American Office of Strategic Services (OSS) agents were sent into the heart of Germany, to obtain and send back military and other intelligence to assist the Allied advance. They were also to establish relationships with anti-Nazi elements, especially underground labour groups within the Reich, who had indicated to the OSS that they would help to shelter and aid agents dropped behind enemy lines. However, conditions were very different from those in the occupied countries, where resistance groups and individuals provided organised help in the form of safe houses, escape routes, parachute reception committees, and so on. Resistance within Germany was mainly passive and fragmented, motivated by political, religious, or personal reasons, resulting in private attitudes…

teleniuslowe@gmail.com Welcome to the July HF Highlights. The 28MHz beacon report for April was compiled by Neil Clarke G0CAS, who reported that DX paths continued to deteriorate throughout April. The exception was to South America, where LU4AA 28200 was heard every day and OA4B and YV5B, also on 28200, were heard on 28 days. In North America 4U1UN and W6WX 28200 were logged on only five and two days respectively although the W5 call area beacons were heard on 12 days. The VK6RBP 28200 beacon in Western Australia was heard on only five days in April, compared with 17 in March. From the Middle East, 4X6TU 28200 was heard on 27 days, 5B4CY 28219 on 29, and YM7TEN on 19 days. A few small isolated Sporadic E openings took place…

keith.g4miu@gmail.com I guess like many other amateurs, I tend to have devices or gadgets in some form or another that I wonder what I ever did without. For me one of these ‘gadgets’ is a Spectrum Analyser. A spectrum analyser is used to measure the magnitude of an input signal over frequency. There are various types of spectrum analyser, for example those used for audio or optical use. The TinySA-Ultra to be discussed here measures input in the RF spectrum. The spectrum analyser displays frequency on its horizontal axis and the amplitude of signals on the vertical axis. In many ways a spectrum analyser looks like an oscilloscope. However, these plot amplitude on the vertical axis but time on the horizontal axis. There are many applications where a radio amateur…

practicalwireless@warnersgroup.co.uk The date was 4 July 2005 and writer and broadcaster Paul Heiney, Figs 1 & 2 was a happy man. As the Newport, Rhode Island sky exploded into a dazzling display of celebratory fireworks he had just completed the OSTAR single-handed transatlantic yacht race from Plymouth, in a time of 35 days, 14 hours and 19 minutes. Of the 34 starters, no fewer than 16 failed to complete the challenging 3,000 mile voyage. Paul’s time was twice that of the victor but that didn’t matter. He had never been in the race to win it; only to execute a voyage well made. But Paul’s story starts a long way from the sea, in Sheffield where he was born in 1949. It may be that sea salt was already coursing…

practicalwireless@warnersgroup.co.uk Fixing holes for the drive are located with the paper template included with it. The S-meter is fitted to the right, Fig. 4. Holes are punched to take the controls under the chassis, as in Fig. 5. An aperture is cut in the chassis to take the flywheel and drive. Holes are positioned for aerial and earth sockets, etc., and under each section of the ganged capacitor: Each coil needs a ¼in. dia. hole and they will be placed as in Fig. 5. The chassis flanges are fixed to the panel with chromed bolts, the bottom of the chassis being 1/16in. higher than the bottom of the panel, to allow for the cabinet flange. Leads are soldered to the bottom tags of the variable capacitor, and passed down through…

For many radio enthusiasts and amateur radio operators, the Norbreck Castle Hotel Exhibition Centre Hamfest in April each year is a highlight of the annual show calendar. I am no exception, having visited this venue, on and off, for more than a decade now. The first NARSA rally was held in the year of my birth, at Belle Vue, Manchester, in 1962. I felt even more drawn to it this year, as the date was my name day, 23 April 2023; St. George’s Day. The venue was, once more, the splendidly faded glory of the Norbreck Castle Hotel Exhibition Centre by the Seaside in Blackpool. This was the 59th NARSA exhibit, and was run jointly by more than 50 Northern clubs around the themes of amateur radio and DXing, computers,…

This piece is about a CB radio I was given, a Midland (Alan) 78 Plus. Now don’t scoff please; a radio is a radio and 11m technology has come a long way since the eighties. This radio, now called a ‘Pro’, is a premium product costing around £80. As Fig. 1 shows, it doesn’t look much different to the CBs we had when (and sometimes slightly before) Mrs Thatcher did her sums and realised legalising CB would bring in a lot of VAT. CB Radios Today So have CBs changed? Well, yes and no. Power remains 4W and the channel knob still clunks round in sets of 40 channels 10kHz apart. (Or so I thought. More later.) UK legal modes are AM and FM, even SSB (but not on this…

Send your letters to: Practical Wireless Letters, Warners Group Publications plc West Street, Bourne, Lincs PE10 9PH E-mail: practicalwireless@warnersgroup.co.uk General Coverage Receiver Dear Don, If you’re thinking of replicating the General Coverage Receiver (May page 32 and this issue) – don’t! At least, not with AF117 four-lead transistors. Many of the RF transistors of that generation (with a fourth lead for the screened case) are self-poisoning and won’t work now even if new-old-stock in a still-sealed package. The AF117 seems more prone to failure than the OC170 and, sadly, Mullard brand are particularly troublesome. This was an unanticipated effect of filling the case with a passivating gel. Tin whiskers grew through the gel from the case until they reached and shorted to the transistor junction. If only one electrode is…