Tabla de contenidos para August 2025 en Practical Wireless

If you are new to amateur radio, or perhaps you used to be active many years ago and have just come back, then you may not want to immediately purchase a new transceiver but make use of an old or second-hand radio. Here I give a first-hand account of the ‘life and times’ of my trusty IC-706 - an old but much loved and relied upon transceiver that is still going. The IC-706 MkII G is a muti-mode, multi-band radio and despite being about 25 years old is still very popular. I brought mine new around 1999 and have used it constantly. It’s great for the radio room at home, out in a car or even for backpack portable [1]. It measures only 17 x 6 x 20 cm and…

The sun was very active once again in May and June. On 13 May it released an X1.2 flare from sunspot region 4087, shown in Fig. 1. The flare was associated with a coronal mass ejection (CME) and caused an HF radio blackout on the daylight side of the world, including Europe and the Middle East. This was followed by a weaker M-class flare shortly after but then, at 0825UTC on 14 May, the sun emitted an X2.7 flare, the largest so far this year. In the early hours of 25 May there was another X-class flare, an X1.1. Another sunspot region, numbered 4100, released yet another flare (at M8.2 not quite X-class, though not far short) on 31 May – with a duration of three hours. This flare led…

Many of us realise that the appearance of homebrew electronic devices such as radios needs to be improved. According to the technical possibilities of the ‘makers’ different solutions were reached – and published for the benefit of other fellow amateurs. During the 2015-2024 era five papers describing methods for panel marking were published in PW. Background When our newly developed and assembled, tested radio, instrument, electronic device is ready, we place it into a case. In the ‘good old days’ we crafted the enclosures (boxes, cases) ourselves by cutting, drilling, bending aluminium sheets, painting (or even anodizing) it, then stuck some letters, figures onto the front and back panels. Time have changed though. Numerous readymade enclosures with various surface finishes are available from parts suppliers, and offered on the internet.…

I have a young lady in my Morse Class, in a wheelchair, who is a Mum, with children at school and a family life to organise. Yet she is still determined to learn Morse and make a success of it. Now, learning Morse is a time-consuming process, requiring dedication, time for practice and so on. So many times I have heard all the excuses for NOT learning the code. We all know this is not really a huge hurdle for a lot of disabilities, so I thought I would delve a little deeper. Blind people Being blind is not too much of a problem. We all know of blind CW operators. As a pianist, I know of several blind pianists and in fact knew a local blind pianist with whom…

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About 24 hours ahead of the 433 Alive event on 26 May, I decided that I wanted to use an antenna with some gain and directivity for the occasion. My household comprises five adults, three cats and an overactive Amazon Prime subscription, so we have a steady supply of cardboard. A recent purchase brought a box with side dimensions about 60cm x 45cm, so I wondered whether a 5-element Yagi for 70 cm would work using the cardboard as a planar substrate in lieu of a boom, with copper foil tape as the element material. A look on K7MEM’s excellent site including antenna design calculators URL below) gave the configuration shown in Fig. 1 (measurements in mm).  https://k7mem.com/Ant_Yagi_VHF_Quick.html As well as the cardboard sheet, I gathered scissors, a sharp craft…

In this month’s On a Budget I have decided to re-visit a reasonably rare yet capable HF transceiver from the 1980’s, the Shimizu Denshi SS-105S. I bought mine a couple of years ago from eBay for a bit less than £150 – and I absolutely love it, using it frequently. Founded in 1972 by Mr Minokamo Shimizu, Shimizu Denshi is a corporation still in existence today, producing power transformers. Beginning in Japan, production later moved to China. For reasons I have not been able to ascertain, but perhaps Mr Shimizu was an amateur, they produced a limited number of amateur radio transceivers which were available part-built to be finished as a kit of parts and pre-assembled PCB’s. Versions Two versions were made available, the SS-105S with 10W of RF output…

Send your letters to: Practical Wireless Letters, Warners Group Publications plc West Street, Bourne, Lincs PE10 9PH E-mail: practicalwireless@warnersgroup.co.uk Out and about Dear Don, I’m reading your comments in the July PW about contents for your Keylines … I do think and I’m very sure you have a subject just in front of you, going portable or mobile ….. It’s a VERY large topic: activating castles, parks, fauna & flora, bunkers, mills, lighthouses and so on … Staying at home, in our shack, and chasing DXCC, that’s nice but sometimes boring when you get that many countries in your logs … I started in 2023 activating castles, we have about 2,700 here in our Kingdom, reached in less than 30 months the unbelievable amount of 500 castles activated, now to…

I’ve recently seen on various Facebook groups, some newcomers to the hobby asking why when they listen on the HF bands, they can often hear stations from Europe and beyond but they cannot hear stations closer to home from another part of the British Isles. It’s a good question and one that cannot be readily explained in a sentence or two on Facebook. Whole books and PhD dissertations are written on the subject of HF propagation, so in a short PW article I will be making some very sweeping generalisations. Many factors Propagation affects each of the amateur HF bands in different ways. Many factors come into play including the state of the 11-year sunspot cycle, the seasons, the time of day and the frequency of the radio signal; these…

It was a slow day on 14.207MHz Long Path 20m to North America, with Stan KE5EE. Unusually, I drifted off to sleep after our regular sked, and when I awoke I decided to pack up. I went from the radio station over to the house and sat in an armchair. I was still a little faint, so I told Sue ZS1AFR, “I’m going to lie down for a bit.” She managed to help me to bed. Unfortunately, I collapsed after the doctor’s surgery had closed. So, Sue set up an appointment for the next day. After getting dressed the next morning, I fainted and collapsed again! So, Sue called out the doctor. I’d already checked my pulse, and it was roughly 32 beats per minute. The doctor came, checked my…

As I mentioned in my introduction last month, GridTracker has been enjoying continuous development and is now a very powerful, if not essential, aid to FT8/4 operation. For those starting with GridTracker, the Call Roster is probably the best place to begin, as it provides helpful filtering of the WSJT-X received data, Fig. 1. By ticking the ‘CQ Only’ box in the top section, the table is restricted to showing only CQ calls. The Call Roster displays all vital information, including the Grid, DXCC country, flag, and prefix. The table can also be sorted on any column simply by clicking the header. When deciding which CQ to respond to, the SNR column (dB) and Age are invaluable. Initiating a call is done by clicking the desired callsign. Grid Tracker will…

Something that makes the NanoVNA so versatile is its ability to measure various RF parameters over a wide range of frequencies. It can be used for testing antennas, measuring the characteristics of filters, amplifiers, cables and other RF components. These parameters are displayed in various ways and one of the more versatile is by means of the Smith Chart. In reality the NanoVNA presents a ‘cut down’ version of the full Smith Chart but it can still provide the user with a lot of information. A description of the use of the full Smith Chart is out of scope here, but I will attempt to describe its basic features when related to the VNA. In this case the chart is generally used with Single (or One) Port measurements. It can…

This is a tale about chimney stacks and amateurs reaching for the skies. We as a family moved to Suffolk from London in 2010. Yes, the TV series Escape to the Country probably played a part in the move. We had been looking to relocate for several years prior and had viewed many properties and made offers on two since 2004. For some reason Suffolk/Norfolk has always had a pull and we have holidayed in both counties for 20 plus years. The property we purchased in 2010 sits at 40m ASL but the chimney stack looked even higher. After a year of contemplating all the options, the scaffolding was finally ordered. I whizzed up and down the ladders while the scaffolding was in place enjoying the views from the chimney…

‘Doppler’ that isn’t one However, these frequency changes at sunset and sunrise (see previous article) are not due to the classic Doppler effect, although this is often explained in the same way, and not only in amateur radio literature. Because the lower F1 layer becomes the higher F2 layer at sunrise, the radio path extended, which leads to a drop in frequency in the Doppler effect. But it increases. This is because the phase velocity of electromagnetic waves within the ionosphere increases with increasing ionisation. As a result, the frequency also increases until this process is complete. At sunset, the opposite effect occurs and the frequency decreases [21]. Many other frequently encountered effects also influence the frequency [22]: Reflection of ionised meteorite channels [23], TID (Traveling Ionospheric Disturbances) [24], solar…