Practical Wireless的June 2025目录

2025 is the 40th anniversary of the Christchurch Amateur Radio Society. This friendly club is located in the seaside village of Mudeford (part of Christchurch) in south east Dorset. To celebrate, the club will be operating the special event callsign GB4MUD from the club house during 1-28 June. At the club meeting on 5 June Duncan Layne G0AHK will be giving a talk on the history of the club which was originally founded as a company club, the Plessey-Christchurch ARS. Over the past year the club ran a successful series of construction evenings, led by Chris Wood G4CWS, teaching different construction techniques, soldering and fault-finding skills. Members built a number of projects, including simple test equipment which could then be used to fault-find their other projects. The club meets every…

This final instalment of switching between antennas and receivers concerns rolling your own distribution amplifier. In the August 2024 issue I wrote about using antenna switches. Last month I wrote about converting a professional distribution amplifier made for the audio-visual industry for amateur use. This month, I want to demonstrate how I rolled my own distribution amplifier, which is useful all the way to 500MHz. The circuit This distribution amplifier connects one antenna simultaneously to four receivers. The limit on the number of receivers that can be connected is that only five BNC connectors fit on the back panel of my enclosure – one for the input, and four outputs. The block diagram of the distribution amplifier is shown in Fig. 1 and I will explain each of the blocks.…

In this month’s On a Budget we are going to build a simple, yet excellent little CW transmitter, which can cover the entire CW portion of the 80m band and fits in an Altoids (or similar) mint tin. Figs 1, 2 and 3. First of all, let me say this is not my design, but that of Peter Parker VK3YE, that denizen of simple homebrew construction down-under. All I have done is build it and drawn a proper circuit diagram that you can easily follow (Peter merely holds up a hand-drawn circuit during the course of a video – not ideal for reproducing here!) There are only 17 active components, plus another seven for the Low Pass Filter (LPF), and the whole thing can easily be built by anyone in…

In August 2023 I reviewed the UMPP (Ultra Miniature Portable Paddle) from GM0EUL keys (website below) and was so pleased with it that I now have two! www.umpp-cw.com Recently, through an online chat in the G-QRP Club forum, I spotted that Peter GM0EUL had produced a new miniature CW key – this time a straight key and called the UMPP-ASK (for Activators’ Straight Key.) A quick email later and Peter agreed to send me one for review, which is the subject of this piece. Description Following his usual methodology of 3D printing, using high quality components, bearings and magnets, Peter has designed and produced yet another magnificent key that far out-performs its diminutive size. Measuring just 55mm long, 25mm wide and 35mm high, this straight key is slightly bigger than…

One of the more obvious uses of a NanoVNA is that of checking antenna matching. This is easily done using a Port 1 S11 Single Port Reflection measurement. When checking an antenna the most common functions that the VNA traces could be set to read are VSWR, LogMag (for Return Loss) Impedance, Resistance and the Smith Chart. Once these parameters are set and a suitable frequency span has been added the VNA needs a User Calibration set. As this test is a Single Port set-up then an SOL (Short, Open, Load) should be carried out. I know I have mentioned this previously but it is worth repeating, the frequency span needs to be given some consideration. The sweep points on devices such as the NanoVNA can be limited. Some models…

Many readers will be familiar with the concept of moonbounce or Earth-Moon-Earth (EME) communications. With the advent of digital modes such as JT65 and Q65 it has become relatively commonplace and even quite modest stations have been able to experience the thrill of making a contact with a station by bouncing signals off the moon. When I read a story from the Deep Space Exploration Society (DSES), Fig. 1, about a project to bounce signals off the planet Venus, I did a double take, wondering if this was a rather elaborate April Fools’ story. But no! You can read the full story, written by Paul Sobon NO0T at this link: https://tinyurl.com/4zzp3bc2 It’s worth summarising the story though – with grateful thanks to Paul Sobon and the DSES. In March 2009,…

In the April HF Highlights we reported on the SV1GA/A operation from Mount Athos, which was cut short after only two days following allegations that the correct authorisation to allow amateur radio operation from the Holy Mountain, Fig. 1, had not been granted. However, on 4 April, the ARRL DXCC Desk issued a statement saying that it “has determined that the operation by a DXpedition team from Mount Athos meets the DXCC award program’s accreditation criteria. Contacts with the team, which operated in January 2025 using the call sign SV1GA/A, will therefore count toward DXCC. Additionally, due to actions taken by local authorities that resulted in the early termination of the operation, any future operations by this team from Mt Athos will require additional documentation for securing accreditation for DXCC…

I first went to the International DX Convention in Visalia in the early 80s and have been several times since, and indeed wrote up my experiences there for the June 2014 issue of PW. However, for a number of reasons that was the last time I attended so it was high time I returned. Back in 2014 I reported that there were some 40 international attendees, including ten from the UK. This time though, the overall numbers seemed to be well down on what I remember and international participation was well down – two of us from the UK, one from Kenya (5Z4VJ, G3AB), one from Switzerland and a couple from Sweden and Denmark. There seems to be some question as to whether the event will run again – the…

As radio amateurs we are commanded that “Radio Equipment is designed, constructed, maintained and used so that its use does not cause any Undue Interference to any wireless telegraphy”. An important part of this is to reduce as far as possible both in-band and out-of-band spurious emissions. Spurious emissions are the emission of radio waves other than those required to communicate. One contributor to in band spurious emissions is noise in the output of a VFO (Variable Frequency Oscillator) or some other frequency generator. Normally a lot of effort goes into making VFOs which are stable and are very clean. While there are plenty of articles about clean oscillators, it is fun to consider for a moment unclean oscillators some of which can lurch from one mode of oscillation to…

BBC coronations: Part XXVI The original plan for television coverage in Europe of the Coronation on 2 June 1953 was for the French television service, Radiodiffusion-Télévision Française (RTF) to provide a direct link from Cassel to Lille of the BBC 405-line signal. Meanwhile, the Dutch broadcaster, Nederlandse Televisie Stichting (NTS), in co-operation with the Institut National Belge de Radiodiffusion (INR, the Belgian French-language television service), and the Belgisch Nationaal Instituut voor Radio-Omroep (NIR, the Flemish-language service), arranged for the signal to be relayed across Belgium to Lopik in the Netherlands via relay points at Flobecq, Brussels, Antwerp and Breda. The conversion from the BBC 405-line standard to the European 625-line system was planned to be carried out at Breda. In the Netherlands, the signal was broadcast by the Lopik transmitter…

Tektronix 465 I have had this ‘scope for some time. Channel 1 worked perfectly but at first channel 2 did not work at all. After re-seating the attenuator blocks and some of the transistors channel 2 trace was restored but was jittery and showed a reduced amplitude and has been this way for a few years. Now was the time to fix it! A more minor fault was that the channel 1 Un-Calibrated light was not working. Given that channel 1 was working correctly and channel 2 worked after a fashion I thought that a power supply issue was unlikely. However, if you need to check these the test points are TP1510: +110V, TP1536: +55V, TP1548: +15V, TP1558: +5V, TP1568: -8V As with the 465B my first move was to…

SINAD: Tony Jones G7ETW explores the significance of SINAD (Signal In Noise And Distortion) measurements. HAMMING WITH MY PACEMAKER: Tom Morgan ZT1T offers reassurance to radio amateurs using pacemakers. REFURBISHING CRT EQUIPMENT: Geoff Theasby G8BMI offers advice on refurbishing old oscilloscopes and similar. VINTAGE TELEVISION & RADIO: Keith Hamer and Garry Smith offer yet more insights into the history of TV and radio, both at home and abroad. ANTENNA RESURRECTION: Tom Tierney G0JSV tackles the challenge of replacing aged antennas. KISS ANTENNAS: Ray Howes G4OWY recommends building antennas, but keeping it simple. There are all your other regular columns too, including HF Highlights, World of VHF, Antennas, The Face Behind the Call and Data Modes as well as your Letters, Rallies, the latest News and more. The publishers reserve the…

LATE BREAKING DX NEWS After several repeated unsuccessful attempts since 2018 to obtain the necessary permits to visit Marion Island and operate from there, Yuris YL2GM finally has got it! Yuris was due to operate from Marion Island as ZS8W between 21 April and 16 May. Prince Edward & Marion Islands is listed as #11 in Clublog’s DXCC Most Wanted List as of April 2025. Yuris was to be on Marion Island as radio engineer and member of SANAP station communication equipment maintenance team and stay there for the above-mentioned period of time, when this year’s annual supply replenishment and exchange of overwintering personnel of the SANAP station is taking place. https://www.lral.lv/zs8w/ THE SECRET GENUIS OF MODERN LIFE: Have you ever wondered about the origins of the smart doorbell? Although a…

Lincoln Short Wave Club members participated in the FT4 activity day at Fir Park Farm. We operated from the club’s NATO trailer, led by Les G1LQB, Marc M7DEU, Ian M7BKF and David M6OYN. Despite challenging conditions, we persevered for the full 24 hours. We used a simple setup, a vertical multi-band antenna and one of the members’ Yaesu 710 radio. We managed to make 311 contacts, and the weather was surprisingly pleasant. It was a great way to start the club’s 2025 SES calendar. We managed to come 4th in our group. Report from Marc M7DEU THE LATEST FROM RAOTA: The spring 2025 edition of our quarterly magazine (OTNews) has been sent to our printer for a proof, prior to distribution, and to John G7OXK who records an audio version…

I’ll begin with an apology. I’ve had to postpone my promised feature on SATSAGEN because I had an issue with my PC. There’s also a new feature that I’d like to include, so all being well, I’ll conclude SATSAGEN next month. This month, I encourage you to upgrade to the latest WSJT-X release. Plus, the new v11 release of VarAC is out, and we’ll look at the enhancements. WSJT-X Now that the latest WSJT-X 2.7.0 has been fully released and settled, I thought it might be interesting to see how well it’s being adopted. A good way to identify the take-up is to use the Stats page on PSKReporter. Towards the bottom of the Stats page, you’ll see an entry titled ‘Software in use’. This lists all the software used…

It has been a long time since I looked at any aspect of home construction. My local club recently started a project for members new to home construction. For many of the members it was a voyage of discovery. I thought it seemed a good idea to pick out some of the issues that members encountered and to provide some hints and tips for PW readers. Printed circuit boards Most commercial equipment uses printed circuit boards (PCBs). In its simplest form, a PCB is a sheet of epoxy or fibreglass board about 2 or 3mm thick with a thin layer of copper bonded to it. The usual approach is to etch, with an acid, gaps between the copper tracks which link the lead of one component to the next. The…

The popular Practical Wireless 144MHz QRP Contest is the ideal way for newcomers to the VHF bands and contesting to get a good feel for many aspects of amateur radio contests. It is an excellent way to experience the thrill of making contacts over many km on the 2m band. This year certificates will again be distributed by email. Power The power limit will again be 5 Watts at the transmitter so that participants with all types of UK licence can participate equally. Equipment The only equipment you’ll need is a low-power 2m transceiver and an antenna. While you can expect to make some contacts with a basic 2m FM handheld transceiver, most of the activity is likely to take place using single sideband (SSB). Most stations use horizontally polarised…

Norfolk ARC recently held two meetings locally in Norwich. Our club meets at the local City of Norwich (CNS) School and we were asked to take part in their Super Science Saturday. This involves several different aspects of the hobby, but one of the most popular with the youngsters is the display that Jim G3YLA usually mans. He demonstrates the use of Morse and gives a challenge to each youngster to look at the code and work out what their names are in Morse and then send it on the Morse key on the bench, a straight key obviously! If they are successful, Jim then presents them with a ‘Morse Code Certificate’ stating that they were able to send their name. This is always very popular with the youngsters. I…