Tabla de contenidos para November 2022 en Practical Wireless

As most of you will be aware, I applied for the use of GB90PW for the month of September, to celebrate the 90th anniversary of Practical Wireless, issue 1 having been the September 1932 issue. There was a slight hiccup with the licence as Ofcom nowadays don’t automatically allow special event calls with two numbers, but they kindly relented given that we have previously held GB70PW, GB75PW and GB80PW (and possibly others before those). The only stipulation was that all QSOs should be made from my location, which ruled out allowing others to operate the callsign from their shacks. This meant that for the most part (with some honourable exceptions mentioned below) I would have to do the operating myself. I set myself a target of 1000 QSOs. However, as…

This is another set donated to the British Vintage Wireless & Television Museum, Dulwich. Incorrectly identified there at first, I immediately knew what it was, as I suspect most of you will: it looks very clandestine. And my title? They were delivered, mainly by air, in 2lb Huntley & Palmer biscuit tins, in which the sets were then in a sealed cardboard box. It would have had a pair of lightweight headphones, 800Ω, and a Bakelite card carrying 30ft of aerial wire and an earth wire. They were supplied either with three batteries, or with two plus a universal mains supply. The need it was designed to fulfil was for a lightweight set that could be used in the field or on mains power. The set weighs 2lb 12oz with…

“I have an NoV for GB9HRH to celebrate the reign of HRH Queen Elizabeth II. I plan to operate 2, 20 & 40 from Merryton Low IO93AD from 10:00. Anyone wishing to pop along and take a turn would be very welcome. Otherwise, all calls are welcome. 73.” Thus, the germ of an idea for a Special Event Station was promulgated. The sudden death of the reigning monarch has caused a shock which was not anticipated, though inevitable. The death of Her Majesty Queen Elizabeth II brought home a realisation of what the UK had lost, for it is clear now that she personified and was the real ‘Jewel in the Crown’. So, an opportunity for radio amateurs to record a unique historic event came into being in a small way.…

Years ago at the SK6NP club I was shown a simple HF antenna, which works on all HF bands other than topband without any need for traps. The SK6NP antenna is 80m of wire in the form of a square whose sides are 20m long. It is a simple antenna, which requires a rather large garden. After enjoying the benefits of this antenna at the club I decided to make a half-size one for my garden in Sweden. The concept is shown in Fig. 1. All you need for this antenna is 50m of wire, some plastic pipes, some trees in suitable locations, rope, some hand tools and little effort. Sadly, I cannot claim to be the inventor of the antenna, the design for the original antenna came from a…

Regular readers of PW will know that I have been using a heavy-duty five-band Spiderbeam antenna since late 2013 – and with great success I should add. However, while I was away on a visit to the UK in mid-2022, the mast supporting the Spiderbeam fell over (see HF Highlights, PW, September 2022), requiring the antenna to be completely dismantled in order for the mast to be raised once again. When disassembled, the effect of nearly nine years’ exposure to the tropical sun on the fibreglass spreaders could clearly be seen, Fig. 1. The Spiderbeam works very well but it is rather a big antenna, requiring an open space greater than 10 x 10m in order to assemble it. As the garden had grown dramatically in those nine years, I…

Readers of this column who are also RSGB members may have read the two-part article in the July and August issues of RadCom by Dr Frank Howell K4FMH and Dr Scott McIntosh, in which the authors outline a new method of forecasting the solar cycle. While the traditional forecasting method by the Solar Cycle Prediction Panel has Cycle 25 peaking at 115 sunspots in July 2025 (i.e. a fairly weak cycle similar to that of Cycle 24), the new projection is for a much greater cycle peaking earlier, in mid-2024, with 190 (±20) sunspots. The monthly solar flux (SFI) is projected to be at 200 (±25) at solar maximum. I’m sure we all hope that the new forecast will be the more accurate of the two, but we will have…

A few months back, I wrote a little bit about analogue hotspots, using a Raspberry Pi based hotspot, such as the G7RPG Microhub, to connect to various analogue networks, including the UK’s Hubnet and the PAPA Repeater system in California. Jef ON8NT mentioned to me recently that there had been a release of the DVSwitch software, which does not require a Raspberry Pi but instead can be run on an Android device. I’ve not mentioned the DVswitch software before, but up until now, it has comprised a server component, which runs on a Raspberry Pi and connects to the different radio networks, including DMR, Fusion and D-STAR. A piece of client software, the DVSwitch app for Android runs on your mobile or network radio device and connects to your server,…

Logarithms (logs) have their uses. By means of log tables and slide rules, they simplify multiplication/division (wake up, Godfrey, it’s electronic calculators these days). They make something seem complicated, hence justifying maths teachers’ salaries (nothing changes there, then). They make the numbers easy when trying to accommodate the huge range of signal strengths arriving at our receivers (now you’re talking!). Those Decibels Let’s move on to decibels. Only, we haven’t actually moved. Decibels (dB) are just another manifestation of logs. Why keep it simple when you can have two words for the same thing? Practical Wireless 2021: May p60 Table 1 calibrated a signal strength measurement as S9 being a voltage level of 50μV equating to–73dBm. Now we’ve got three numbers for the same thing: S reading, voltage and something…

Looking back to September 2021, this day seemed a long way off. In my mind I had an overall plan of how things would look; when I’d finally got the new station up and running, but the details of how exactly I’d achieve it were not yet complete. In some ways I made the detailed plan up as I went along, section by section. Strangely, and it is hard to explain, sitting in the completed shack feels like a bit if an anti-climax. After months of digging through soil and bricks, burying conduit in the ground, cutting through concrete pathways and diamond drilling through walls, sitting in front of a desk with working radio equipment feels a bit ‘oh, okay, everything works. That’s good’. In our old house the shack…

There is no question that the superhet receiver offers far superior performance figures to those of the t.r.f. However, the constant reminder that one does not get something for nothing is very evident in this statement. With the superior performance comes additional and often complex circuitry, together with the need for a fair array of test equipment with which to tune and align the finished receiver for peak performance. Very few serious amateurs or s.w.l’s these days would dream of using a t.r.f. in fact the majority would probably laugh at the idea. Yet in the past these receivers were extremely popular and one reads of simple circuits giving truly amazing results. The writer wished to use “double” valves for a particular application, but not having had a great deal…

Upgraded Anytone AT-5555 Plus V3 10m Mobile Transceiver The Anytone AT-5555 PLUS now has the new the RX noise reduction option (NRC). With a completely new designed PCB board the Anytone AT-5555 PLUS is one of the most modern and up-to-date 10m radios on the market. Updates and new (menu) functions are: • VOX • CTCSS/DCS codes • RX compander • Noise gate • RX noise reduction (extra PCB inside the radio) • Program cable connector on the backside of the radio (program cable is optional) • Extra ventilation holes on the top and bottom cover Available from stock at Moonraker for £169.95 plus p+p. GB22YOTA From Jamie Williams M0SDV: This year we are hoping to get the callsign GB22YOTA, pending Ofcom approval, and I would like to invite you…

I was recently approached by the RSGB to give a talk for their Tonight@8 series of online lectures. The brief was to cover conversational data modes. The talk went ahead as planned on the evening of 5 September and seems to have been well received. However, as part of the research for the talk, I pulled some statistics from the PSK Reporter website. Unsurprisingly, this showed that a frighteningly large proportion of data modes contacts occur using fixed format messaging systems such as FT8, FT4 and WSPR. These modes have little or no opportunity for any conversation as they pass the bare minimum of contact information in a fixed format. Depending on when you look at the stats, you will normally find that greater than 99.5% of all reported data…

Well, yes, some can. Many of us have been affected by the new Ofcom regulation of moving antennas away from neighbours by at least 4m. I have had to do just that. Living in a bungalow, and not having enough space for a tower and beam, verticals are really my only option. My homebrew (Mk.1) vertical was a roach pole of approximately 6m with a 9:1 UNUN and earthed with some 22mm copper pipe into the banks of the stream at the bottom of our garden. It was fine on the upper bands, and okay(ish) on the 40m band (or so I thought). I felt, though, that if I had to move it, then I may as well try to get the best out of a replacement. When I initially…

An experimental lightweight 12V DC powered rotator is described. Many of the parts can be created on a standard 3D printer, providing ease of replacement or modification. I created this little rotator so I could rotate a small 1296MHz beam on top of a 15m telescopic fibreglass mast but I have also used it to rotate other antennas such as lightweight dipoles (10, 6 and 4m band – see header photo) and VHF HB9CV antennas. The rotator might also prove to be useful to remotely position ferrite rod receive antennas for LF and VLF reception. Specifications • turn time 12V (360º): ~10 sec • turn time 6V (360º): ~20 sec • mass of rotator: 500g • fits 22mm mast (two clamps) and 40mm mast(side fixed, see text) • Note: this…

7-9 October THE RSGB CONVENTION: https://tinyurl.com/34e7m8ya 14-15 October THE NATIONAL HAMFEST 2022: George Stephenson Pavilion, Newark & Nottingham Showground, Lincoln Rd, Winthorpe, Newark, Notts. RG24 2NY (Local and international traders; B&B | Books | CBS | Clubs | CR | FM | RSGB | SIG). Tickets can now be purchased online. http://nationalhamfest.org.uk 14-16 October JAMBOREE ON THE AIR / INTERNET (JOTA/JOTI) 2022: Ready for an amazing digital and radio Jamboree? JOTA-JOTI 2022 promises to be the best ever, with an improved digital & offline experience for participants around the world. With so many opportunities to learn, play and connect with others, the Scouts are here to help guide your experience in a new way […] https://tinyurl.com/28kf4n6y https://tinyurl.com/332cyyvj https://tinyurl.com/tarw8hny 16 October HORNSEA ARC RALLY: Driffield Show Ground, Driffield, East Yorkshire YO25…