In RadCom for September 2021, CARA member John G8CQX wrote about a wide band HF loop antenna with a high-performance amplifier which he had designed and built. As described in September’s CARA News, he has recently developed a simpler version of the amplifier (easier to build), but still with a good performance. At our November meeting he will tell us how it all works and answer any questions we may have.
Towards the end of the meeting John will ask for firm expressions of interest from members who wish to build their own amplifier. He will then procure all the necessary components and assemble them into kits. The cost should be in the range £30-£40. He is NOT offering to supply the PEX barrier pipe which forms the actual loop, nor the T to support the loop, nor the coax cable to go between the loop assembly and the shack. Cash payments will be preferred at the time to guarantee delivery of the kits.
Thursday 16th November at the Premier Suite, Cheltenham Town Football Club, Whaddon Road GL52 5NA. Doors will open by 7.30pm for an 8pm start. The bar should be open as usual.
Prospective members and visitors will be made welcome, as always.
Thursday 19th October. 7.30 for 8pm at the Premier Suite, Cheltenham Football Club, Whaddon Road GL52 5NA.
A talk by Roger G4BVY on HF Propagation. The talk will cover the fundamentals of HF propagation, explain some of the terms/numbers used, explore how to predict propagation, describe means of real time monitoring of propagation and look at the causes and effects of sudden disturbances.
Given that we are at around the maximum of the current sunspot cycle, when HF conditions should be at their best – at least for some of the time! – this talk promised to be of great interest to club members and especially to those who operate on the HF bands. It should appeal to newcomers and “old timers” alike.
Roger is travelling some distance to give this talk so do please come along and make his trip worthwhile.
Aerials, Transmission Lines (Coax), Transmission Line Transformers and Transformers.
Thursday 21st September at the Premier Suite, Cheltenham Football Club. 7.30 for 8pm
The stimulus for this talk was my lack of understanding of how to determine the voltage at the end of an aerial, needed for the new regulations, and the operation of the 49:1 baluns so often used to feed wire aerials. The answer, it turns out, to these and other problems is to be found in determining and analysing the equivalent circuit of the aerial, transmission line, transmission line transformer and transformer.
In the talk we will look at the early contributions to radio of Faraday, Maxwell and a little known maverick Heavyside, and see how a telegraphy operator sorted out a load by identifying the correct equivalent circuit for a transmission line. We will then look at the equivalent circuits of the afore mentioned RF components and see how wonderful computers are at doing sums to give us an insight in to the operation of these RF components. Don’t worry I will keep the maths to a minimum and give you a warning before showing any equation! While there will be a few equations in the talk, it is my intention to provide a clear practical view of how these devices work rather than produce a maths induced coma in the audience.
At the end of the talk I hope we will all be able to go away having a better understanding of how aerials, transmission lines and transformers work.
Thursday 17th August in the Premier Suite at the Cheltenham Town Football Club, Whaddon Road GL52 5NA.
The doors will open by 7.30pm for viewing and the auction proper will commence at 8pm. If you are likely to bid, on arrival you should sign-in and collect a bidding card. Bids will accepted only from those with cards. Lots will be sold as seen. Please note that some of the equipment may use high, dangerous, voltages – proper care must be taken when using such equipment.
Payments must be made at the end of the auction and may be made by cheque (if presenter is known) or cash. No lots may leave the room until paid for.
In the years following WW2 and in the days before “black boxes” appeared from the Far East, Heathkit produced a wide range of kits for radio amateurs – and for the audio market. These kits proved to be very popular as they provided an affordable route for many amateurs to own equipment which performed well. Although originating in the USA, Heathkit had a factory in Gloucester which produced Anglicised kits for the UK market. Early products included the DX40U and the DX100U AM/CW transmitters, both of which can still be heard on the air today.
This month Brian G4CIB, accompanied by his wife Leta G4RHK, will tell us about Heathkit’s history and will no doubt mention the role played by local amateurs in the factory. He will be bringing along examples of Heathkit products and encourages CARA members to bring along their own examples for display and perhaps discussion.
Thursday 20th July 2023 in the Premier Suite, Cheltenham Town Football Club GL52 5NA .Doors will be open by 7.30pm for an 8pm start.
Do come, it will be an interesting and informative meeting. Visitors and prospective members will be welcomed, as always.
A change to the previously advertised meeting – an auction will be held at the Churchdown Club in Church Road on Thursday 15th June to dispose of the contents of three local shacks belonging to recent Silent Keys. Doors will open at 7.30pm for an 8pm start to the auction. There is limited carparking at the club which should be reserved for those delivering equipment and those who are disabled. There is a carpark further up the lane beside the club.
If you are likely to bid, on arrival please sign-in and collect a bidding card. Bids will be accepted only from those with bidding cards. Lots will be sold strictly as seen. All purchases must be paid for before the items are remove from the room.
The auction is a join venture between the Cheltenham Amateur Radio Association and the Gloucester Amateur Radio and Electronics Society.
The aim of this meeting is to encourage home construction and to help demonstrate that amateur radio remains a technically based pastime.
Members are invited to bring along as many exhibits as they wish which must conform to the following rules:
Entries must have some relevance to amateur radio.
Entries must not have been shown at a previous CARA exhibition.
Entries must have been constructed within the previous few years.
Entries must have been built or heavily modified by the exhibitor.
Kits built by the exhibitor are permitted.
Exhibitors must be members of CARA.
The following awards will be available for presentation:
The Bill Brown G5BK Memorial Cup for “Best in Show”.
The Pat Moore G3IKR Memorial Cup for “Innovative Construction”.
The Roger Kendall G0UPU Memorial Cup for “Best Software or Computer Related Project”.
An exhibitor winning the same award for two consecutive years will not be eligible for that award in the following year. However the judges may reward such an entrant with a certificate in lieu of the award.
Thursday 16th March, 7.30 for 8pm at the Premier Suite, Cheltenham Town Football Club, Whaddon Road, Cheltenham GL52 5NA. Visitors and prospective members are welcomed to attend.
A “Skills Evening” is the title of this month’s meeting. The format will be slightly different from previous such meetings as it will start with a short presentation to the whole room by Mike G4GHL, he will be explaining to us how to use VNAs (Vector Network Analysers) to measure things like antenna impedance and feeder loss.
After this we will be able to look at the various tables around the room where other members will demonstrating or showing various skills. Needless to say there will be plenty of time to chat and to visit the bar if you wish. Do come along, it promises to be an interesting evening.
Thursday 16th February 2023 at the Premier Suite, Cheltenham Football Club, GL52 5NA.
Doors will be open by 7.30 for an 8pm start.
Visitors and prospective members will be made welcome, as always.
Mike G3TSO is a long standing and well known member of CARA. He is a former professional aviator who spent many hours airborne making sure that the aircraft that he was in arrived at the correct destination and on time! Needless to say he accumulated much experience and is hence well qualified to talk to us about how radio systems are used in the field of navigation. His talk will be illustrated by PowerPoint type pictures.
.We look forward to an interesting meeting. The bar will be open as usual for the sale of tea and coffee as well as alcoholic drinks.
Thursday 19th January 7.30 for 8pm at the Premier Suite, Cheltenham Football Club, GL52 5NA
Visitors and prospective members will be made welcome.
At the last Fun Field Weekend in the autumn it was agreed that we would hold another such weekend on 9th, 10th and 11th December. At that time we had no idea that this would turn out to be so cold and snow bound!
The site chosen was high up in the Cotswolds between Brockhamton and Hawling. The weekend started out well on the Friday with tents and masts being erected in passable winter conditions but come Saturday the weather turned cold and by Sunday the snow had started to fall, and fall heavily.
The above photo, taken on the Sunday, shows the main operating and “mess” tent complete with flue from the in-tent log burning stove.
Some fun was had on the Saturday playing radio, including by Tony G3YYH who turned up early to join the VMARS 80m AM net on 3615kHz. which starts around 8am. The main tent was kept warm(ish) by a log burning stove and members gathered inside to eat and to socialise.
Inside the main tent with Mike G8NSZ on the left and Rich M0XRB warming themselves by the stove.
Come Sunday morning with the snow thick on the ground the decision was taken to “bug out”, as the military saying goes. The site was abandoned in quick order with most of the non-radio kit left in situ for collection later. The journeys home were slow and difficult. For example Tony G3YYH took some two hours to complete what should have been a 15 minute trip, and Rich M0XRB took much of the day to return to Cheltenham. The kit abandoned on site was collected over the course of the following week as road conditions improved.
One CARA member, hearing of the problems encountered, remarked that those at the site must have been slightly mad to venture out in the winter; the riposte from one who was there was: “No, not slightly mad, but completely mad!” Nevertheless it hasn’t dampened enthusiasm for another winter weekend camping out to play radio!