Peter King We desperately need to locate a new and more central venue for our more formal meeting/presentations/club projects. Several of us have spent quite some time hunting around but get little either little response from queries, expensive quotes in large (cold?) rooms etc. It would be great if someone could step up and push this forward … Read more
PREVIOUS MEETING A really big thanks to Matt G4IYT for a fascinating talk and demonstration of 3D printing with examples of amateur radio and other applications. 20 members and guests attended.
Wednesday 8th November saw 15 enthusiastic club members vist the RSGB’s visitor centre at Bletchley Park, the home of the code breakers. The club was treated to an insightful talk about the visitors centre and some of the history of the site. After splitting into two groups we took a tour of the exhibit hall … Read more
Two new pages have been added to the VARC website. 1. With many thanks to Peter G3UHN – in the operating section we now have a page giving details of how to program your radio for FM repeater operation. 2. With thanks to Bob G4PVB – we have a page dedicated to receiving the very … Read more
After an extended period of building maintenance, World Heritage Grimeton Radio Station has scheduled* SAQ to be on air on UN-Day, Tuesday October 24th 2023 at 17:00 CET (15:00 UTC), to send out a peace message to the whole world, using the 200kW Alexanderson alternator near Grimeton in Sweden from 1924, on 17.2 kHz CW. … Read more
In this ever growing website, we have now added a page dedicated to Slow Scan Television. You can find it by to to the webpage HERE!
Upcoming on the 28th of October is the 48 hour CQ WW SSB contest. We entered this one last for the first time in a long time last year and it proved to be a very good and enjoyable event. We are looking to set up and enter again this year, so if you are … Read more
For anyone that might be interested, there is an activity event on 2m happening on Saturday 30th September (’23) between 1:00 and 3:00pm. This is an organised activation consisiting of a series of nets that covers most of the UK. The nets are chaired so that stations can be quickly passed around to get as … Read more
We had quite a turn out for the working party this past weekend (3/9/23). As a result we have moved the repeater antennas off the pump up mast and mounted them on the VARC tower. The pump up mast has been moved to one side to allow room for work to begin on the shed … Read more
The ProblemMost general coverage receivers have adequate gain and you can hear the background atmospheric noise from the receiver’s bottom frequency limit of around 30 to 100 kHz up to their maximum frequency of 30 MHz: that is except for the “Medium Wave” range of 500 kHz to 1.620 MHz. The reason that most receivers … Read more
Recap on the ThyristorIn a previous article, I explained how a thyristor worked. This is a transistor-like device in which the current through it, (between anode and cathode), is controlled by the thyristor gate. However, unlike a transistor, the “through current” is not proportional to the gate current in a linear manner. Instead, the current … Read more
Electro-Magnetic radiation is not confined to broadcast, commercial and amateur bands, and figure 1 shows a significant portion of the electro-magnetic spectrum including the visible part. Particularly note the “fierce” logarithmic scales of frequency and wavelength. This is necessary to accommodate the huge range between “radio” waves and gamma rays in a single diagram. This … Read more
Some things can go faster than light, but not ‘material’ things. Three examples of these things are; the cutting point of scissors, the meeting point of lines as the lines go from crossing to parallel, and the phase of a wave. But these are imagined things, things in the mind. In the case of waves, … Read more
It would be no good removing the man-hole cover in the pavement and directly measuring the resistance between the metal pipes at either end of the plastic section, as these would be effectively shorted out by the surrounding earth, so I decided to simulate the real situation by measuring the resistance of a length of … Read more
Back In the hastily rearranged talk to the club on Tuesday, 21/11/06, Brian, G3YKB talked about many different methods of home construction of experimental or “one off” circuits. These included: conventional printed circuit board, strip board, “paddy board”, ugly bug, and others, and also how to make screened enclosures by soldering sheets of single sided … Read more
It has a similar layout to the alternators used for generating the country’s electricity supply, except that instead of having 6 poles for generating 3-phase 50Hz AC, it has 600 poles for generating single phase AC at 17,200Hz. It also rotates somewhat faster than the alternators supplying the national grid, and delivers 200 kW of … Read more
Back This is not really about amateur radio, but it is technical and it involves electricity. Have you ever got the Christmas Tree lights out from the box in which they had been carefully packed the previous year only to find that they no longer work? If so you will know that finding the offending … Read more
Back There has been some discussion on whether it is better to wind inductors as a torroid or as a solenoid on non magnetic material. Thoughts:-Magnetic lines of force add vectorially. They do not influence one another. Hence: The result of this is that the field near the centre of the solenoid is proportional to … Read more
AB INITIO PERFECTUS EST (or in plain English, this “From first principles” series is finished). This series of technical articles for the VARC Newsletter is now concluded. It has ranged over more than 3 decades and some 80 articles, although in the early days its publication in the VARC Newsletter was somewhat irregular. Its original … Read more
Back A dipole in free space, fed at its centre by a balanced feeder, can radiate all the RF power fed to it with no radiation from the feeder. Such a system is illustrated in figure 1. A dipole is a “resonant” aerial and its first “self resonance” is when its total length is approximately … Read more
Verulam Amateur Radio Club now has it’s remote station running from it’s site near Dunstable. This is running most HF bands and proving to be very successful. It is operating using the RemoteHams software, which is a free download from the Remote Hams website. Once downloaded you can search for VARC and access the radio. … Read more
Rhombic for 6m One thing I have fancied playing with for a long time is the Rhombic antenna. It has a very good directional gain and in principal is easy to construct. The problem is that on HF a Rhombic is extremely large. Even on 6m the antenna is pretty big! My idea for the … Read more
Back In “radio science”, ‘Q’ stands for Quality factor. In a simple resonant or tuned circuit, (and indeed also in a single inductor or capacitor), Q is conveniently summarised as “the component’s reactance divided by the component’s resistance”. The higher the Q, the lower the loss in the component’s resistance. (In most tuned circuits it … Read more
AB INITIO Back Puzzling facts As we approach the festive season of Christmas crackers, games and puzzles, it was thought once again that it would be appropriate to divert to something “Scientific” rather than strictly “Amateur Radio”. Everybody knows that the tides on the sea are due to the “pull of the moon”, but a … Read more
2018 was another step up in Verulam Club contesting with some very good results. The three main entries were made in the RSGB Club Championships, The Autumn Series and also our annual entry CQ WW CW. I know personally, and also from others I talk to that this year has seen a distinct improvement in … Read more
We are very proud to say that Verulam ARC has taken the first place position in General Section of this years 1.8 MHz AFS Club Calls Contest. Well done to all those who took part, a good time was had by all! Coming up we have three AFS contests in January in which we encourage … Read more
Contesting Pages Contest Home Page On Going Contests Cabin and Contest Diary CQ WW CW Contest The final results have been released for the 2017 Club Championship competitions. We have managed to hold on to our seventh position in the ‘General Club’ category. This is out of a total of 45 entrants in that category, … Read more
Contesting Pages Contesting Home On Going Contests Cabin and Contest Diary We are now in the planning stages for this years CQ WW CW contest. This is a 48 hour Morse contest which we run from our ‘cabin’ site. We will be running four stations for the whole of the 48 hour session, so there … Read more
Visit Contests Page Introduction The Club Championship is an RSGB run contest that operates for six months from February until July, with three contests each month covering SSB (voice), CW (morse) and Data modes. This is a contest where multiple operators can submit their entry on behalf of the club, and all their scores are … Read more
