From this basic configuration, additional tuned elements can be mounted inside, as long as unused band elements are earthed. This means that multiple frequencies are fed on separate feeders via a selector switch.
Element lengths are calculated and reflector and director elements added to produce antennas that are more efficient than Yagis, and easier to feed, especially at 6 metres.
Phil expanded on his research showing the evolution of the Tilted Terminated Folded Dipole (T2FD). Excellent for fitting into attic spaces by folding it into a Z-shape, it has a lower noise figure compared with other antennas. Although the TTFD has a terminating load that dissipates power, manufacturers like Yaesu offer them for sale.
Linden M0TCF and Pete G3ZVI took turns to present their favourite designs and the club looks forward to more discussions on this fascinating topic.
Earlier Slade M6SQB and Rob 2E0UJM tracked the Chinese LilacSat as it made a high pass over the club. They found this satellite difficult because it uses a non-inverting transponder, meaning the Doppler shifts are double the usual amount.
26 April 2017 Dave G3SBP gave a fascinating talk about JT Modes, invented by astrophysicist Joe Taylor K1JT for moon-bounce operations. Short 13 character messages are exchanged once a minute over dedicated frequencies available on each amateur HF band. A complete QSO takes 6 minutes to exchange call sign, grid locator and signal strength. At this slow rate, low powers of 5 watts allow an amateur to reach the whole world.
The WSJT-X program runs over the same hardware as Fldigi and takes only an hour to learn to use. Pre-programmed response messages are automatically generated, leaving the amateur to only choose which to transmit. Stress-free digital modes at last! As a bonus the program has a full Weak Signal Propagation Reporter (WSPR) interface as well.
Following on from last meeting's workshop on amateur satellite antennas, Slade M6SQB rushed out to buy an Arrow antenna. He programmed in frequencies to cover the Doppler shift of passing popular satellites and was rewarded with contacts in Guernsey, Belarus and Spain on Saudi-Sat (SO-50)
This evening he showed club members how to use this antenna. While Rob (erstwhile M6UJM) used smartphone apps to locate compass bearings and pass predictions, members assisted in locating the next pass of Amsat's Fox-1A.
A Spanish ham was heard as the satellite rose over the NW horizon but a contact was not able to be made with him. Club members Dave G3SBP, John G3WVM and Martin joined in to help with pointing the antenna using the satellite prediction app.
As Linden M0TCF observed, this is wonderful aspect of our hobby that allows Foundation Licence holders to work European amateurs on VHF/UHF with only 5 watts.
12 April 2017 Guest Pete G0ABI talked about his experiences working satellites in low earth orbit (LEO). Inspired by a TX Factor feature, he uses a Baofeng radio, a £135 log-periodic Amsat Elk antenna and the RSGB guide. After programming the Baofeng using CHIRP he was ready to contact European and North African operators.
Digital modes and SSB are also possible on LEO satellites. New clusters of small Cubesats are launched every few months. Follow their progress at AMSAT's website. Read more in the ARRL Guide and AMSAT-UK.
Dave G3SBP spoke of his experiences working geostationary satellites in the 1980s and making QSOs from Hong Kong to the USA using AO-20 and AO-3D. He was so committed to the hobby he donated to the satellite construction costs and was rewarded with his name on a plaque. Unfortunately the satellite failed after a week! In those days a satellite dish and 20 watt amp were needed.
Geosynchronous orbit satellites may return in 2017. They will operate on 10 GHz and will be available for use as emergency services.
12 April 2017 Congratulations to Rob M6UJM and Alex M6WEK on passing their Intermediate Licence examination at the first attempt. They now apply to OFCOM for their 2E0 callsigns. Special thanks to Linden M0TCF for developing his unique licence training course and seeing each of these Foundation licence holders successfully though. Well done to everyone!
10 April 2017 This afternoon the Exeter Raynet team changed the GB3EX repeater aerial. The steel and aluminium pole has been replaced by a 20ft aluminium pole as used at the GB3EW repeater.
Keith G7NBU, Pete G3ZVI, Allan G1JXI and John G3WVM did the tough work while interested ham wannabe Steve Davies manhandled his monochrome camera!
The original ground plane-less aerial was used. The array is now much easier to rig as the pole can be stepped into the brackets from ground level and slid up or down in the U-bolts. The UHF omni-antenna is now about 4ft higher. We look forward to reception reports from the South West and Wales.
22 March 2017 With the "Gray Line" passing over the club meeting at 7 p.m., Rob M6UJM brought in his Icom IC-7100 and Buddipole with a home-built 60m dipole to try some DX. Slade M6SQB assisted in rigging Rob's inverted-V dipole and his antenna analyzer showed it to be resonant at 5.316 MHz with an SWR of 1.1.
Bas G0FGE stepped up to the Morse key and was soon calling CQ. Unfortunately, with solar activity so weak, there were few stations to be heard. A Faroe Island operator called CQ and soon moved on hearing no response.
Club members gathered to offer advice. Although the WebSDR station could hear contacts, our cub location and antenna were just not in the right position.
8 March 2017 The Exeter Amateur Radio Society held its 2017 Annual General Meeting. Club officers were unanimously elected to their positions.
Chairman: Keith G7NBU
Secretary: Slade M6SQB
Treasurer: John G4AP
Publicity Officer/Webmaster: Nick M0NRJ
Committee members: John G3WVM and John G8XQQ
Congratulations to all!
The Training Officer post is yet to be filled.
Afterwards Ivor G6ATJ put on a video show which drew from TX Factor and Radio Caroline's history. TX Factor Episode 3 featured the Exeter Radio and Electronics Rally.
The 2017 Exeter Radio and Electronics Rally attracted over 150 bargain hunters to America Hall, Pinhoe. Sausage baps and tea soon made everyone forget the blustery weather outside as visitors pored over new and used items on sale from dozens of vendors. Many acquaintances were renewed as old friends met again. Pictures show the scenes inside America Hall and the Sunnylands Room.
22 February 2017 Nick M0NRJ spoke to club members about hardware required for amateur radio digital modes. With a choice of hundreds of types of computers coupled with hundreds of radios, the interface between any pair is going to be a personally crafted solution. Manufacturers such ZLP Electronics sell units that have a range of connecting leads to cope with the permutations. The picture shows a mobile rig with a ZLP adapter linking a Yaesu FT-857D and a laptop running Fldigi.
Fldigi is one of the most popular computer programs for multiple data modes, especially as the solar minimum's poor propagation makes regular HF contact unpredictable. Nick has published a document about using the Fldigi data mode macros. It walks users through the sequence of commands needed to get the most from these invaluable shortcuts.
Some computer/radio combinations don't need protective isolating transformers and can be home-built such as John G8XQQ's device he is using in this picture. Nowadays, modern radios such as Kenwood KX-3 have USB interfaces so there is no need for special adapters.
20 February 2017The GB3EX repeater has been restored to normal operation again. Thanks to Pete G3ZVI, Allan G1JXI and Keith G7NBU for their quick response and deploying their engineering skills so effectively.
16 February 2017Due to a fire on the site GB3EX has been removed for safety; we hope it will be restored within 7 days.
8 February 2017 Project Night at the club, with members presenting a "show and tell" of their most recent work. Star of the show was Alex M6WEK and his two projects for college work. An Arduino Uno used a Ublox 7 GPS receiver to display five sequential screens of GPS data. His Portable Raspberry Pi ran Chirp, Fldigi, QSSTV, Xlog and Xastir using a USB sound modem.
Rob M6UJM showed his Watson Antenna Analyser covering DC to 2 metres. A review of its features appears in the RadCom October 2015 issue. It is self-calibrating and has "Easy" or "Complex" modes of operation. This will enable him to get his Buddipole tuned up.
Stuart G3XYO showed a switchable CW audio filter for reducing in-band interference. Pete G3ZVI showed a PCB board with a slit carved into it that is a 23 cm antenna.
Nick M0NRJ explained how he used a breadboarding kit to develop the next generation repeater controller. An ATMega328P processor uses a DS3231 real-time clock to maintain accuracy over years. As a surprise for CW enthusiasts he presented his latest woven scarf sample featuring Morse code characters of his callsign.
Finally Keith G7NBU described his Clansman 320 (2 - 30 MHz, 30 W) that he wants to convert to PSK-31 operation.
He showed why each module was needed to supply life support, science research, propulsion, storage, living quarters, health and happiness required by the crew. A dizzying array of acronyms on top of an orientation guide (forward, aft, port, starboard, zenith and nadir) helped members adjust to what was up and down.
If you are in Exeter, then you can see the ISS fly by at these times. Well done Slade for producing such a comprehensive talk and answering all our questions! Photos courtesy of NASA.
Paul G4RRA brought in clever addition to his iambic Morse keyer that allowed him to record and playback CQ calls, as well as play preprogrammed messages. Essential for competitions, it gives valuable catch up time for log entries while sending the next CQ call.
5 January 2017 Ivor G6ATJ brought his Icom 7300 and Keith G7NBU brought in his Elecraft K3. Ivor reports that they set up both radios next to one another and used Slade M6SQB's 20m HF whip to test reception. Unfortunately HF bands were completely dead. The Icom saw SWRs of well above 3 and refused to autotune, so transmitting was out of the question. Keith removed the top panel of his self-build and everyone peered in. He and Ivor both answered questions about their radios.
Keith praised Water & Stanton for impeccable customer service when he rang them to say that the delivered Elecraft kit had a few missing parts, and received them the following day.
Ivor praised Martin Lynch & Sons for their equally impeccable customer service as well. After he had returned from their premises with the 7300, an MFJ analyser, and a power supply (a “REAL” PSU, not a switched mode one!), he had connected everything up and much to his dismay, the 7300 exhibited some peculiar behaviour...it didn't work basically!. Discovering the cause to be the PSU, a call to ML&S resulted in an apology, and a courier that had been arranged for the following day to collect the faulty PSU AND drop off a replacement with no quibble. (The PSU was apparently current limiting far far too early, and not providing the promised 25Amps @ 13.8V)
Meeting Themes 2017
24 May: DMR v Fusion v DSTAR 14 Jun: HF antennas 28 Jun: How to build a repeater 12 Jul: Morse practice/VLF Radio 26 Jul: Software Defined Radio 9 Aug: Hamnet 23 Aug: HF Propagation Prediction 13 Sep: VHF/UHF antennas 27 Sep: 60m on the Gray Line 11 Oct: Fldigi for Raynet 25 Oct: Bodycams for security staff 8 Nov: Filter theory/2018 Topic planning 22 Nov: Morse practice/ex-military radios 13 Dec: Bring in something interesting evening 27 Dec: No meeting