Tabla de contenidos para April 2024 en Practical Wireless

Something a little different this month. I’m writing this while awaiting my flight home from East Africa. This was my first time in this part of the world and it’s been fun – the weather is milder than West Africa, which I know well, and it’s always interesting to experience propagation from a different part of the world. I started in Uganda with Alan G3XAQ. Alan put up a Moxon antenna for 10m, made from wire and fishing poles, which worked well. As a second antenna, I put up an elevated quarter-wave vertical for 12m, with two wires by way of a ‘ground plane’. That too worked remarkably well. We operated only on CW but always had big pile-ups whenever the bands were open. Our equipment consisted on Alan’s Elecraft…

One of our long serving volunteers to the GB2CW Morse scheme, Martyn Vincent G3UKV, Fig. 1, has become a silent key. Martyn had been running GB2CW at 0900 on 3605kHz every Thursday morning for many years. He was also an RSGB Morse code Assessor, plus a very valued Vice Chairman of Telford and District Amateur Radio Society. He was responsible for the running of the famous Hamfest with great success. He will be sadly missed by all. Losing volunteers like Martyn is always very sad; a fact of life of course, but it is also very difficult to replace people like him. It is not very often that I bring news of a ‘new’ volunteer, but the fact is that we do need many more around the UK. It can…

The relatively new FT-710, a very competitively priced, high specification, full SDR radio, has gained great respect. Like all the similar radios from the big names, it has a spectrum scope/waterfall display. It’s tempting to treat these just as pretty pictures but in theory these can in most cases be used quantitatively to measure a range of received signal and noise level parameters. To analyse the FT-710, the figures below were obtained using an RF signal generator, the Elecraft XG3 Signal Source [1] giving several preset levels on each amateur band, including –73dBm, 50µV, S9 into 50Ω and –107dBm, 1µV. The microphone was unplugged, obviously. An external switched attenuator was also available to set levels in 1dB steps. The spectrum scope on the FT-710 is divided into ten divisions vertically,…

HF-100 REVIEW: Richard Constantine G3UGF reviews an unusual compact antenna from Taiwan. PORTABLE MILITARY RADIO COMMUNICATIONS OF WWII: Graham Caldwell completes his series of articles on WWII portable radio equipment, including their collecting potential. This issue will cover Imperial Japan and the Soviet Union. RADIO IN THE BRITISH ISLES IN DECEMBER: Chris Burger ZS6EZ says “DXFC ruined my life!” JUNK TO JOY: Billy McFarland GM6DX describes how to construct a simple ARDF antenna. A WSPR BEACON: Colin Campbell MM5AGM takes readers through the design and build of an Arduino-based WSPR beacon. AN EASY ARDUINO NANO VFO AND SIGNAL GENERATOR: Steve Macdonald G4AQB offers a simple-to-build project based on low-cost modules. There are all your other regular columns too, including HF Highlights, World of VHF, Antennas, Book Reviews, Vintage TV &…

It’s great to be able to report that another ‘145 Alive’ event has taken place, encouraging FM activity on the 2m band. This time it was organised by Mark M0XIC and John M0XJA and took place on 27 January. Mark and John put together a summary for the event, which reads: • 33 nets operated on the day• 18 nets were in England, 4 in Scotland, 4 in the Republic of Ireland, 3 in Wales and 4 in Northern Ireland.• An average number of contacts logged per net was 29.• The longest distance contact was 352km.• The total number of contacts recorded was 854. Carl Gorse 2E0HPI operated from Cringle Moor in the North Yorkshire National Park, Fig. 1. Carl used an IC-7100 running 50W to a Slim Jim antenna…

Following the Ofcom Licensing review, I’m going to look at some of the implications. This is far from an exhaustive review, but will focus on some practical implications of the changes, particularly in respect of what Ofcom term ‘Regional Secondary Locators’, which most amateurs would probably term callsign prefix (e.g. GM, MW, etc.). I have used xxx to anonymise the callsigns I’ve used as examples. Callsign prefixes The very clear message for all operators is that if you are going to log your contacts and upload them to one or more of the popular web-based systems, then you need to log and upload the actual callsign you used on the air with the correct account. For example, you cannot expect these systems to match a contact you made while on…

In the first two parts of this series, I presented new publicly available bench test data on HF transceiver transmit noise (Part I) and compared these radios to their Sherwood receive performance, what they cost when entering the amateur market, and the overall satisfaction that hams say they have with them (Part II). In Part III, I put these results together for practical use by amateurs seeking to purchase a new HF transceiver in this list. Can we identify transceivers having low transmit noise, high level receive performance, at a lower market-entry price, and that are rated with higher satisfaction by ham operators? Yes, we can! The reader is left with subjectively evaluating the radio in terms of features, ergonomics, and other personal choice elements. I present the results of…

The early German blitzkrieg, employing close communication between tanks, infantry and ground attack aircraft, placed a new order of importance on allied radio development. Portable radio sets, issued as far down in the military echelons as the platoon, were thereafter continuously redesigned and improved. America was a latecomer to radio technology, having lagged behind Britain and Germany in radio research and development between the wars. In 1939 the US Army possessed only two suitable, yet inadequate, AM (amplitude modulated) radios at the small unit level. However, America caught up quickly and surpassed its rivals in radio innovation during the war thanks to its vast industrial and scientific resources. The pioneering use of FM tactical radios led to the SCR-300, the army’s first true walkie-talkie, which first saw combat service in…

The tinySA Spectrum Analyser and NanoVNA Vector Network Analyser are so affordable that many of us now own one, or both of these instruments. Brilliant as both these instruments are, they have some physical shortcomings, notably the use of PCB-mounted SMA connectors and the open ‘sandwich’ construction of my NanoVNA is not the best for outdoor or benchtop use. SMA vs BNC It may well seem intuitive having bought a NanoVNA or tinySA to utilise their SMA connectors, but there are good reasons for not doing so: • The standard connector used on most test equipment, certainly on mine, is the BNC so it makes sense to standardise on these.• SMAs are only specified for a limited number of connection cycles, about 100 for good SMAs, substantially less for cheap…

My local radio club in Taunton recently decided to hold a Build-A-Thon, with the aim of encouraging members to have a go at building from kits. While it was mainly aimed at those who had never built an electronic circuit before, a number of people who had not built for many years also participated. In order to provide some variety and yet simplicity, the Club decided to order several different kits from Kanga Products here in the UK at the more simple end of their range, including a CW keyer/training oscillator, an FM radio for the Broadcast bands, a dummy load and an SWR resistive bridge. Members were able to choose the kit of their choice and had a couple of hours to build them on a club night. I…

It seems odd to be writing this, because it was an article by the Reverend George Dobbs G3RJV in PW May 1983 that convinced me I could build my own amateur radio equipment. I have been doing so ever since and have enjoyed it very much. 40 years later I find myself as Chairman of the G-QRP Club and writing for PW. This particular project came about following feedback that there were few ‘starting from scratch’ project articles for newcomers to homebrew radio construction. I had to agree and when several people suggested revisiting the SCD, one of George’s classic projects, I did some research. The original SCD project was a crystal-controlled transceiver capable of being used on 80, 40 or 20m and was published in Short Wave Magazine between…

Send your letters to: Practical Wireless Letters, Warners Group Publications plc West Street, Bourne, Lincs PE10 9PH E-mail: practicalwireless@warnersgroup.co.uk Simple receivers Dear Don, Another excellent issue. The article by Daimon Tilley G4USI brought back memories from the past. I too played with the ZN414 and built small medium wave radio sets. Our local BBC home service on 276m came from the Postwick transmitter a few miles east of the city of Norwich so we had very good signals into the city. In the mid to late eighties our son built this minute MW radio as a school project (see photo); they were fortunate to have such a science teacher! This example used a ZN416E and was one of many at that time, no doubt these can still be found on…