Innehållsförteckning för March 2025 från Practical Wireless

On 1 January 2025, the business of power amplifier manufacturer RF-KIT was transferred to the newly founded company RF-POWER GmbH, based in Salzburg, Austria. “In order to meet the increasing demand for our power amplifier, production had to be expanded. Naturally, the tasks that my small company had to cope with also increased. That’s why I had been looking for competent support for some time,” says Reinhard Förtsch, head of RF-KIT, explaining the reason for the move. This necessary ‘man-power’ is now supplied by RF-POWER. The owner and managing director of RF-POWER GmbH is Wolfgang Klier, OE2VEL. He has been Managing Director of the Austrian company ViCOS GmbH, which manufactures professional electronics, since 2004. “We have been producing the RF2K-S power amplifier from RF-KIT since spring 2024. We will continue…

In December 2024, the latest batch of the hotly anticipated annual Klingenfuss radio publications came out. In the main, the 2025 offering from Germany comprises the following items, containing, according to the blurb, ‘secret’ HF signals and frequencies for SDR fun’ – well, not so ‘secret’ anymore, when using these: • The 2025 Shortwave Frequency Guide • The 2025/2026 Guide to Utility Radio Stations • The 2025 Super Frequency List on CD • The 2025 Frequency Database for the Perseus LF-MF-HF Software-Defined Receiver • The 1997-2025 Digital Data Decoder Screenshots on USB Stick (28,000+from 600+ stations). The Klingenfuss 2025 Shortwave Frequency Guide (SFG) The Klingenfuss 2025 Shortwave Frequency Guide is the 29th edition of this global HF frequency listing. It runs to 336 pages – the same length as the…

When visiting amateurs, the subject of how to earth equipment frequently arises. It is then time to look at how the station is wired up. Most often the transmitter is connected to an antenna tuner unit (ATU) and then to an antenna, but seldom is there a wire from the earth terminal on the set or antenna tuner going to an earth rod. I then explain that they must have two earths, one safety through the mains supply, which is the three pin mains supply plug, and then a separate RF earth. What is an RF earth? In general, it is a wire connected to the last piece of equipment going to an earth rod in the ground. If a station is on the ground floor, then all they require…

BBC coronations: Part XXIII In the previous column, we mentioned that the BBC used specially designed zoom lenses, manufactured by Watson & Son and Taylor, Taylor & Hobson Limited, (originally formed in 1886 by brothers William and Thomas Taylor), for television coverage of the Coronation on 2 June 1953. Another special innovation, relatively new to television in 1953, was the Dallmeyer 40in Double-Folded Telephoto Lens. Such a device was fitted to a camera positioned at the Victoria Memorial facing Buckingham Palace. Its horizontal angle (in conjunction with an image-orthicon pick-up tube) was as little as 1.75°, which enabled a very close view of members of the Royal Family during their appearances on the balcony. An angle of this order called for extreme care during broadcasts as any slight shake or…

The variable frequency oscillator described here may be used to control the two-band speech transmitter (January. 1965. P.W.) so that no crystals are needed. It enables the transmitter to be tuned to any frequency in the 1.8 or 3.5Mc/s amateur bands. The v.f.o. may be employed with other transmitters. The fundamental operating frequency is 1.75-2Mc/s but output may be taken at 3.5-3.8Mc/s if a different transmitter requires this. Fig. 1 shows the circuit and the VR150 regulates the anode and screen supply for the 6AG7. L1 the oscillator coil. is tuned by VC1 from 1.75-2Mc/s. There is good isolation between L1 and the anode circuit and L2 is tuned to about 1.9Mc/s and needs no further adjustment. A coaxial lead takes r.f. to the transmitter. Heater and h.t. currents are…

As I start to write this month’s column it is 7 December 2024 and storm Darragh is raging. My recently installed attic flower Pot antenna for air band is working well and I have been listening to Stansted airport and Essex radar on my R532 receiver while monitoring numerous aircraft, as displayed on Global ADSB exchange, performing missed approaches due to the gales. https://globe.adsbexchange.com I have already taken down my HF OCFD due to last week’s storm Bert, because as regular readers may remember, I cobbled together a couple of flimsy poles to mount it on and I have yet to improve them. So rather than have something break I have taken them down. As today was a good day to sit on the radio I temporarily strung 33ft of…

Power supplies are an essential part of the shack’s equipment. Using one power supply to power a radio or several radios usually requires either a linear power supply or a switched mode power supply to be bought or made. In this case the choice of a linear power supply, albeit an easier design, was not considered for the shack due to the total component cost. The transformers alone would probably need to be specially wound and the total project cost would be prohibitive. The target was to build a 13.2V 20A power supply to power two rigs in the shack, with sufficient power to run one in transmit and the second in receive. Generally the maximum running RF power to the antenna is 50 watts, this equates to about 8A…

Yaesu has quietly added three new mobile VHF/UHF transceivers to its website. The FT-3185RASP, FT-3165RASP, and FTM-150RASP all focus on Yaesu’s Super-DX feature, which is designed to improve weak signal reception. While that feature isn’t new, Yaesu has added an Audio Digital Signal Processing Unit (ADS) that also activates when engaging Super-DX. ADS is designed to further improve weak signals. All three models include ADS as part of the improved Super-DX feature. Product highlights include: FT-3185RASP: 85W 144MHz FM Mobile Transceiver, fanless operation FT-3165RASP: 65W 144MHz FM Mobile Transceiver, includes a front speaker FTM-150RASP: 55/50W 144/430MHz FM Dual Band Mobile Transceiver, detachable front panel  http://www.yaesu.com SWR METERS: Moonraker have just taken delivery of a range of VSWR meters covering from 1.8-1300MHz. Prices start from £29.95. SWR meters are helpful when you’re…

There is a line in the very watchable film Ice Station Zebra when Patrick McGoohan says “Our British camera developed by our German scientists and your US film developed by your German scientists was in a Russian satellite developed by their German scientists”. The important thing there, of course, being all the German scientists involved. So, here we have a German made radio used by the French Secret Service based on a World War II British designed radio set. Indeed, this set is actually a development of a previous copy of the British set the Germans had earlier produced. The famous British set, the B2 as it was known, was the SOE mainstay in use during WW2 and was used throughout the occupied countries by SOE agents and resistance units.…

While reading the article Radio and Maps – Mapping Radio by Georg Wiessala in the October 2024 issue of PW, my attention was drawn to the picture of the MFJ-890 Beacon Monitor. This device displays the activity of HF beacons within the NCDXF/IARU International Beacon Project. To do this it synchronises with a time signal and then lights up small LEDs on a map as and when they become active on the chosen frequency. The user then listens to that frequency to see if beacons can be heard. In doing so they gain insight into the current HF propagation conditions. The whole device is just 6.75 x 5.25in, quite compact. This got me thinking. Instead of going looking for beacons that I may be able to hear why can’t I…

The UK Government’s recent controversial decision to return the Chagos islands in the Indian Ocean to Mauritius led inevitably to questions about Britain’s other dependencies around the world. David Lammy, in the House of Commons, hastily assured his fellow MPs:"/ “I want to reassure the House, and all members of the UK family worldwide, that this agreement does not signal any change in policy to Britain’s other Overseas Territories. British sovereignty of the Falkland Islands, Gibraltar and the Sovereign Base Areas is not up for negotiation. The situations are not comparable”. The sensitivity of the Falklands issue comes as no surprise as memories are still fresh of the way the Government of the day was caught entirely unprepared on 2 April 1982, when Argentina invaded and occupied the Falkland Islands, a…

Those regular readers out there will have seen my article in September 2023 called Makeshift PSU detailing the step-by-step guide of turning a PC PSU into a power supply for your transceiver. Recently a newly licensed amateur approached me discussing this article. They felt that they lacked the nerves and skills to open up a power supply and hard wire the transceiver’s power leads but they had some soldering ability and had access to stock PSU’s. This got me thinking of creating an adapter that allows you to plug and power your transceiver without opening up the PSU and dealing with high voltage components. I started searching online a found the ideal item that could be altered to allow you to simply plug into the PSU, giving an electrical connection…

Later on in the column, you’ll read a lot about meteor scatter, including some information which certainly made me stop and think and I’ve been enjoying operating meteor scatter since the mid-1980s! But lest you think that very complicated equipment is needed to find out about meteor scatter, I connected my 2m receiver, linked to my PC running the WSJT-X software to my V-2000 vertical during the Geminids meteor shower in December and was very surprised just how many stations I logged! I’ve included a map, Fig. 1, of the stations I logged. I did the same in the Quadrantids shower in January too, although the results were not quite so good. Perhaps I missed the peak of the shower. Remembering Gaston Bertels ON4WF Jef Vanraepenbusch ON8NT writes, “From 25…

Back in the very early days of the ‘Imperial Scheme’ of antennas spanning the industrialised globe, the inverted-L design he used was repeatedly claimed by Marconi to be directional. This comes as a surprise to any amateur enthusiast who has ever used the same design of antenna. Now, John Rowlands MW1CFN who wrote the history of ‘Carnarvon’, one of Marconi’s transoceanic VLF stations, has teamed-up with Fred Chumaceiro to produce the first-ever NEC-5 computer model of the first iteration of the 1.1km-long antenna that operated, at the time, at around 21kHz from the windswept north Wales mountain slope of Cefn Du. The two researchers learned of each other when texts they had written – Chumaceiro about Curaçao receiver ‘Daniel’ – appeared in a recent IEEE newsletter. Remarkably, Chumaceiro’s work included…

If there is one thing we all need from time to time, it’s a cheap PSU. I’ve been playing with some ex-PC power supplies, but they’re due to leave me in a few days. Before they go, I’ll share what I learned. The first ATX Fig. 1 was the start, a ‘converted’ ATX switch mode computer power supply I was given. This can provide 30A at 12V, which is impressive. With such computer-use SMPUs, RF optimisation was not a design consideration. Perhaps I was lucky, but I had no issues on HF. That said, I’ve mainly used this to power a range of Chinese 2m/70cm mobiles, a CB I was mending and a Bluetooth class D audio amp. It’s been good as gold. The second ATX For £5 I bought…

Breaking news as we go to press is that another operation from Bouvet Island has become a good possibility, thanks to a large financial donation by the Northern California DX Foundation. Scheduled for February next year, the large and highly experienced team, led by Kenneth LA7GIA, plans to operate as 3Y0K from ‘the most remote uninhabited place on earth’ for three weeks. More information closer to the time and on their website: 3y0k.com Atlas of QSL Cards Last year I was asked by Martti Laine OH2BH if I could help with the production of a book being written by a friend of his, Laura Piipari. At the time I was in the throws of moving back to the UK after nearly two decades living abroad and I didn’t want to…

A Rotatable Quad Dear Don, Not so much a letter but to say I made this rotatable quad from two 4-way conduit boxes and 8 lengths of cut 20mm conduit and short length of wood (simple and cheap as chips) and hung it off my 80m dipole wire antenna. I am surprised at the gain on 10m. Also easy to rotate. The design is from All About Cubical Quad Antennas by William Orr W6SAI. 73 Doug G4VZR Coaley, Glos. (Editor’s comment: This takes me back to my own first ‘gain’ antenna Doug, also a quad from that book (albeit a different one) and also for 10m. I couldn’t believe how much difference it made compared to my previous dipole. And it cost a magnificent total of 2/6 (12½p) using garden…

SDRplay nRSP-ST SOFTWARE-DEFINED RECEIVER REVIEWED: Georg Wiessala checks out this new product from SDRplay. USING MMANA-GAL TO DESIGN AN END-FED CFR DIPOLE: John McDonald G8PJC shows how to design your own Controlled Feeder Radiation antenna. 4m BAND QUAD WITH TWIN FEEDER - A UNIVERSAL VHF ANTENNA: Jonathan Hare G1EXG offers another innovative antenna design. RESTORING AN ICOM 290A: Tony Jones G7ETW gets a real ‘oldie’ working again. HAMMER IT WITH MSHV: Billy McFarland GM6DX explains how to set up the MSHV software to increase your QSO rate during a DXpedition or similar. There are all your other regular columns too, including HF Highlights, World of VHF, Data Modes, Antennas, What Next, The Morse Mode and Amateur Radio on a Budget as well as your Letters, the latest News and more.…