CTARC JOTA Event 19 - 21 Oct '18

We still require a few members to assists us with Jamboree on the Air 2018.

This year it will be held on Friday 19th to Sunday 21st October 2018.
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This year we will be setting up a station at the Sea Scout base in Muizenberg.

We need persons to help us set up the station on Friday 19th in the afternoon from 12h00 ish. (Please confirm time with Noel, ZS1FW  or John ZS1AGH. John’s e-mail: zs1agh at telkomsa.net )

In previous years, we used the Girl Guide Hall in Bergvliet, but the Sea Scout base may be more suited to our purpose.

JOTA-JOTI is the largest Scouting event in the world with over 1.3 million Scouts participating across 150+ countries.

Scouts and Guides across the world connect with each other during JOTA-JOTI using the airwaves and the internet.

The event has traditionally been held the third weekend of October since 1957.

More on JOTA - 19-21 Oct '18

We received the following letter from John ZS1AGH about the forthcoming Jamboree on the Air event, in which the CTARC usually participates. Access the map here.

CTARC Further Club History - 2 Jun '18

Here's another photo, kindly provided by Dennis ZS1AU.

At a JOTA-type outreach activity are, L to R. Ted Baker ZS1RA (former Cape Town Branch chairman) and Sydney Smith ZS1PF at the microphone, along with two avid Lakeside Sea Scouts.

CTARC Heads-up for JOTA/JOTI - Oct '18

Here is an early announcement for the forthcoming Jamboree On The Air / Jamboree On The Internet, which is set to take place on the weekend period of Friday 19th to Sunday 21st October 2018.

JOTA is a long-established opportunity for radio amateurs to assist the Scouts / Guides / Wolf Cub / Brownie groups within your community to make international radio contact with similar groups worldwide.

You can download the JOTA/JOTI Participants Guide as a PDF file [here].

More information is on the JOTA website [here].

Report-Back on October Meeting - 22 Oct '16

The Cape Town Amateur Radio Centre held it’s October 2016 Meeting on the 22nd, starting at 14h00. The meeting, which was very well attended, was opened by Paul / ZS1S, who welcomed us all. He took the trouble to welcome back a number of old friends who had not been at the club for some time, as well as a number of newcomers, some of whom have just written their RAE and yet others who are involved with technical subjects at UCT. We do hope the newcomers will be joining our club, which now has a paid-up membership (and excluding life members) of over seventy strong.

We remembered Richard / ZS1RIC who is currently attending his wife in hospital, and we welcomed back Hugo / ZS1HSF, who has returned from a spell in the white house.

Noel / ZS1FW then gave a report-back on the recent JOTA field station set up in Meadowridge on Saturday. See that report [here].

Noel also gave us feedback on the recent antenna work party held at the clubhouse on the 8th October - details [here].

We were shown the new CTARC name badges that the club hopes to have produced and have ready by the November meeting – details [here].

Details of the forthcoming November 2016 meeting (details here) and January 2017 meeting (details TBA) were mentioned.

We were all reminded to get in the nominations for the Len Wells Ham Spirit Trophy – details [here] – which must reach Dennis / ZS1AU by 31 October.

There was also a brief mention of a recent Memorandum of Understanding being drawn up between the SARL and ICASA.

The very successful Bring and Buy / Swop Shop was also announced and is discussed [here].

Then it was time for Paul to introduce John / ZS1PM, an electrical engineer (now retired) from UCT who has had a long and fascinating career, both in amateur radio and in the field of professional RF engineering.

John described his introduction to radio when a neighbour, Herbie Taylor / ZS1JK came on air with a signal sufficiently strong to blank out the green “magic eye” tube on his parent’s radiogram! This lead to a visit to Herbie and an introduction to the world of radio. In 1949, the CTARC was called the Cape Town Branch of the SARL and used to meet in the Cape Town YMCA Hall.

Through Herbie, John met Max Adler / ZS1ACD, who was a gifted musician and piano accordion player. John was so impressed by a performance given at the Hotel Cecil in Claremont that he took up lessons with Max and later joined his band of accordion players in Johannesburg, where he was to meet his future wife!

John described a visit as a schoolboy to the radio station in Milnerton, which was the radio communications receiver link to the UK. At the time it had five 100m tall masts with wire beam antennae. The transmitter station was a little further away at Klipheuwel. The link consisted then of just two duplex voice channels and an RTTY channel. The Milnerton receivers were 1930’s Marconi rigs with separate tuning controls for RF Stage, Oscillator and Mixer – none of this new-fangled ganged-tuning nonsense!

In those days, what with all the war surplus equipment still available, radio components were in plentiful supply. Certain companies foresaw the potential of the hobby market and Jack Twine started the Hamrad company. Later on he was joined by the Morris bothers and Hamrad moved to larger premises.

In those days, ham transmitters were home-made. 807 and 813 beam tetrodes, and 809 and 811 triodes were used. Antennas were most wire -  folded dipoles, long-wire and ground-plane verticals. There were few beam antennas in Cape Town then. When John moved to Constantia to a larger property, there was enough space for him to put up a 270 foot long wire  antenna. Later on in his talk, John was to show us his homebrew 100 mW crystal-controlled transceiver with which he was able to work Joburg – via Tippy Marais (ZS1CL)’s beam antenna!

1957 was a peak in the solar sunspot cycle - (a maximum that has never been  achieved since then) and correspondingly there was a great interest in amateur radio. John would work the Eastern Coast of the USA on the long path and have QSO’s with good signal strengths with just 50w of power into his LW antenna.

In those days, even before Springbok Radio came on the scene, there was just the “A” programme (English) and the “B” programme (Afrikaans). For a little variety, L. M. Radio would magically rise out of the static on 11.7 MHz in the early mornings in the summer months. Receivers were Hallicrafters SX28’s (which had been made in quantity for the war effort), Hammarlund, Eddystone, the legendary National HRO and, for those with the necessary folding stuff, the Collins 75A series, which were accurate down to 1kHz and stable enough for SSB (although most ham transmissions were on AM at the time).

John built a dual band double conversion receiver for 7 and 14 Mhz (21MHz was to only become available later). He also was building homebrew transmitters and made his first contact with the USA in 1954 using 50W. Later he was to acquire an enormous transmitter (christened “Big Bertha”!) that had been a beacon transmitter, which he converted to the ham bands. Sufficient was its output power that he could walk around the garden at 100 metres distance holding two fluorescent tubes that would light up! Prudently, Big Bertha’s usage was limited to occasional test transmissions.

A cubical quad antenna for 28 Mhz was used by John to work New Zealand with regular success.14Mhz contacts with New Zealand were more difficult.

When John graduated, he travelled to the UK and worked there, then, after a spell in Cape Town working for IMC he went to the National Institute for Telecommunications Research up in Johannesburg at Wits University. Working under Dr Hewitt, he met and worked with Dr Trevor Wadley. One of the first projects was an Ionosonde instrument, used to measure the height of the ionosphere at different frequencies thoughout a 24-hour cycle. The MUF (Maximum Unsable Frequency), (HPF) Highest Possible Frequency and OTF (Optimal Traffic Frequency) charts put out by the NITR and – extremely useful to radio amateurs – were published in Radio ZS for many years.

John then spoke about the Tellurometer, Dr Wadley’s invention (and a first for South Africa in the world) that was to revolutionise the practice of Surveying. Up until then, surveying was carried out by measuring angles and using Trigonometry to work out the distances between beacons.The Tellurometer measures the transit time of a (GHz) radio wave between two points. Making allowances for the speed of the wave through the medium, one can calculate the distance accurately.

In 1959/60, John worked on the first solid-state Tellurometer (you can appreciate how surveyors would have appreciated not having to lug “valve” equipment and associated large batteries up to mountain summits!). Throughout his talk, we were made aware of the gradual improvement of radio components, from bulky valves, through whiskery germanium transistors, through to silicon transistors, through to integrated circuits, with the consequent effects on the possibilities of miniaturisation. 

So too were there developments in accuracy and calibration. Initially, equipment was calibrated against the WWV time signal. Later on a Hewlett-Packard frequency counter at the NITR provided  accuracies in the order of 1 Hz at 20 MHz. While much of the ancilliary circuitry could become solid state, the source of GHz frequencies had to remain hollow-state - the Klystron (and its appropriately bulky power supplies) - for some time.

The Tellurometer is still very much in use to this day, though the technology has become far more portable. Many specialised variations have been developed for specific surveying applications.

John also touched briefly on the technology behind the legendary Wadley Loop, which was to revolutionise receiver tuning, stability and design methods, as illustrated in the Racal series of receivers.

After his talk, John kindly answered some questions from the floor, and then it was coffee, biscuits and the chance to peruse the items brought for sale or swop. All in all a great meeting. Thank you so much to John for his very informative talk, and to all others who attended and participated. We look forward to seeing you all at the November Meeting!

Paul / ZS1S opens the meeting and welcomes all

A well-attended meeting - and they kept on arriving!

Noel / ZS1FW gives his report-back on the JOTA event

Pauk introduces John / ZS1PM (on left)

John's talk provided a fascinating insight into the development of
radio in South Africa, for young and old alike

Above: "Big Bertha", John's massive transmitter that started off as a
beacon transmitter, and was later converted to the ham bands.

The late Trevor Wadley, inventor of the Wadley Loop
and the Tellurometer

John shows us his homebrew crystal-controlled transceiver

Afterwards, the chance to socialise and chat

Danny /  ZS1BL, with some of the UCT crowd who attended

   

CTARC Report-Back on JOTA Event - 17 Oct '16

In response to very positive feedback from last year's event, the CTARC put up a field station again for the JOTA weekend on Saturday 15th October 2016, at the Meadowridge Scout Hall, off Ladies Mile.

Noel /ZS1FW reports that the event was well-attended by Boy Scouts and Girl Guides, who responded with enthusiasm at the chance to make supervised contact on with others on HF and VHF. An HF wire antenna was erected and some contacts were made despite the rather disappointing solar figures.

A morse code key and oscillator were also set up at the station, which also generated great interest.

Thanks to all who assisted with the setup, running and take-down of the station afterwards.

Photos will be added here presently

CTARC Forthcoming JOTA Event - 14/16 Oct '16

This year the Cape Town Amateur Radio Centre will again run a field station for JOTA (Jamboree On The Air).

The JOTA event involves many thousands of members of the Scouts and Girl Guides association being given the opportunity to make supervised radio contacts with other Scouts and Girl Guides internationally, via radio amateur stations.

This year the CTARC will, as with last year, set up a field station at the Meadowridge Scout Hall. Noel /ZS1FW, who is managing this event for CTARC, envisages setting up the station on Friday afternoon, and operating on Saturday, taking the station down either on Saturday afternoon or Sunday.

Interested hams who would like to take part in this worthwhile and rewarding activity are please to contact Noel via the CTARC email address

CTARC Report-back on Meeting of 24 Sept '16

The Cape Town Amateur Radio Society held its monthly clubhouse meeting on Saturday 24 September 2016. The meeting was well attended and was opened by our chairman, Rob / ZS1SA. He gave us some feedback on the recent Committee Meeting, some news about repairs to the 145.750 MHz repeater antenna on Tygerberg, he mentioned forthcoming events such as Field Day and JOTA, and then handed us over to the main topic and speaker of the afternoon.

This time we were treated to a talk by Peter / ZS1PGC, proud owner of a RigExpert model AA-600 Antenna Analyser. The "600" portion of the model number indicates how high in frequency the device can measure - in this case up to 600 MHz. There are higher-frequency models, which come with appropriately higher price tags!

Radio hams like to optimise their antennas in order to "get their signals out". This involves measuring the antenna's operating characteristics (resonant frequency, Standing Wave Ratio, impedance, radiation resistance, and capacitive and inductive reactance being the main parameters). We have relied on a range of tools to measure them. Traditional tools such as Grid Dip Oscillators, SWR meters (and even light bulbs!) have been used. More recently the MFJ range of antenna analysers have made the task of tuning antennas to resonance far easier.

The RigExpert range of analysers has, however, shifted the paradigm yet further, as we were to learn from Peter's enthusiastic demonstration. He showed us how his device can not only measure the above parameters for a particular frequency, but draw graphs of the antenna's performance over a wide range of frequencies. In seconds.

By linking his AA-600 to a laptop computer, Peter was able to project the results of each scan onto a screen via the club's video projector, sharing them with the audience

Peter had brought some antennas along to show how the AA-600 quickly draws a graph of the SWR, the Return Loss, Impedance, Resistance and Reactances of an antenna. He zoomed into a portion of the SWR graph to show the low-value SWR's (between 1.3:1 to 1.0:1) on a narrow bandwidth of, say 5kHz., and then even narrower bandwidths. This makes for precision "fine tuning".

Peter then showed us some tricks his analyser can do, such as "Multi-SWR" (showing various frequencies where low SWR's are to be obtained), Time Domain Reflectometry and even Smith Charts! The TDR function was particularly useful to check on quality of coax cable and could even show how far down the cable the barrel connectors were situated! The Smith Chart function was fascinating in its ability to show the true points of resonance and low SWR of an antenna. Peter was even able to show us how two antennae in close proximity to each other (though electrically disconnected) could affect the SWR of the main one.

The purchase price of this versatile instrument was justified, as Peter put it, in that he was "buying a whole training course on antenna parameters and behaviour". We could see his point as we all quietly wondered which heirloom rig we could sell to fund the purchase of an AA-600...

Sadly, the afternoon wasn't long enough to allow for the full range of capabilities of this remarkable instrument, but Frank / ZS1CM and John / ZS1AGH also made appropriate contributions to the topic after Peter's excellent talk.

Paul / ZS1S rounded off the afternoon by showing us a fascinating Dubillier widget that could (theoretically) use the mains wiring of a house for a receiver antenna. Clearly intended for use with hollow-stage receivers and developed long before sensitive MOSFET front-ends were in use.. Eek! Use with caution.

After the meeting, outside, great interest was shown in a mystery high-power RF (transmitter?) unit that has been kindly been made available to our club (photos at the bottom of this article). Festooned with dials, verniers, power valves, coils and other components, this item would be the ideal addition to any shack or man cave (for those of us who have any space left there, that is...)

All-in-all an excellent, educative afternoon for our club. Thank you to all for attending, and especially to Peter and the other contributors.

Our Chairman, Rob / ZS1SA opened the CTARC meeting, reported back on
the recent committee meeting, mentioned forthcoming events and activities,
then introduced Peter / ZS1PGC - main speaker of the day.

Peter has obviously found the RigExpert to be a fascinating
piece of antenna test gear, which offers a wide range of capabilities

He set up the RigExpert to link to his laptop
and the CTARC video projector

Here the RigExpert shows a range of SWR values, with two main
low-SWR "spikes" across the frequency range
(Apologies in advance for the variable quality of screen shots, which were
shot at an oblique angle and later retouched)

Detailed parameters could be called up instantly

Radiation Resistance can be charted against Reactance

SWR can be determined, initially over a broad frequency range...

...And then over a narrower frequency range, for greater accuracy

Peter also demonstrated the units ability to
draw Smith Charts, in order to find
"real" points of antenna resonant frequency

Peter demonstrated how the RigExpert analyser could show how
non-connected metal elements (e.g. reflectors and directors) can affect the
main antenna's SWR and other parameters

Using the RigExpert as a Time Domain Reflectometer, Peter showed us
how to check coax cable for quality, and even how far down that cable
a connector, or a fault, can be located

Frank / ZS1CM also expounded on the complex issues of antenna
performance and Smith Charts

John / ZS1AGH also made a contribution to the debate about cables,
using a medical analogy

Paul / ZS1S ahowed us a fascinating Dubillier widget that purports to let
you use your house mains wiring as a receiver antenna

Tony / ZS1TK brought along this fine yagi that Peter kindly analysed for him

Something attracted the attention of some members over there...

It appears to have fallen from the sky...

Anybody have any idea as to just what
the mystery RF item... is???

CTARC Feedback from JOTA Station - 31 Oct '15

We received this nice letter today from Kyle Cato about the recent JOTA Station we held in Bergvliet on 18/19 October:

Dear Cape Town Amateur Radio Centre

Thank you the experience with using the radio. I will enjoy coming next year and try meet more people on the air.

Thank you


Kyle Cato
2nd Bergvliet Sea Scouts

Our club's secretary, Anne, wrote back:

Dear Kyle
 

Thank you so much for your e-mail.

We are so glad you enjoyed yourself and are looking forward to the next one.


Best regards

Anne
(CTARC Secretary:)

So, it looks like we might be doing JOTA again, next year! Well done to those dedicated CTARC members who made it all possible.

CTARC JOTA Station at Bergvliet - 17 / 18 Oct '15

Members of the Cape Town Amateur Radio Centre set up a JOTA field station for the Bergvliet Scout and Girl Guides on the weekend of 17 / 18 October 2015. The location was the Scout- & Girl Guide Hall in Glen Alpine Way, Bergvliet in the Cape Town southern suburbs.

The antennas used were the club's WD3ZZ dipole for 40 & 80 metres, as well as a TA33 beam antenna on a lightweight rotator.

Present during various parts of the weekend were: ZS1FW /Noel, ZS1AGH /John, ZS1BL /Danny, ZS1S /Paul and ZR1HPC /Hylton. Thank you to those who assisted with setting up the station on Friday, , operating it during the weekend and dismantling the station after 10h30 on Sunday.

In spite of relatively poor propagation- and solar figures, (on 18 October the Sunspot Number was 51, the Solar Flux was 89, the A Index was at 22 and the K index at 2) contact was made with several other JOTA stations during the course of the weekend.

Grateful thanks to Noel / ZS1FW, for providing the initiative behind the event, and to Paul / ZS1S and John / ZS1AGH for the photos.

 

CTARC Report on September Meeting of 26 Sep '15

On Saturday 26 September 2015 at 14h00 the CTARC held its September meeting, which was reasonably well attended in spite of rather cold and windy weather.

The afternoon began with our chairman, Rob / ZS1SA, calling us to order. He gave us a report on the recent committee meeting of 21 September, and the various forthcoming events with our club will be involved:

• The club has disposed of its old trailer by selling it to one of our members. The trailer had been sitting unused for several years and was accumulating fines for unpaid vehicle registration fees;

• On the weekend of 17/18 October, the CTARC will run a JOTA station for the Bergvliet Scouts and Guides. Noel / ZS1FW is driving this project;
  
  
• Our Saturday 24 October monthly meeting will be the screening of the video of a DX-pedition to Chatham Island, kind courtesy of Barry / ZS1FJ via Paul / ZS1S;
• We also plan to operate ZS1CT during the forthcoming Field Day exercise;
• Our final monthly meeting of the year will be on Saturday 28 November, which will be the CTARC End-of-Year function;
   
• Next year, the CTARC celebrates its 70th anniversary. We eagerly await members' input and suggestions on how to commemorate this auspicious milestone.

Further details on the above forthcoming activities will be published on this blogspot and announced in the regular CTARC Sunday morning bulletins.

In addition to this, Rob mentioned our club had recently been featured in an article in the Southern Suburbs Tatler newspaper. (See that article here)

We then proceeded with the main event of the afternoon. John / ZS1AGH gave us a fascinating lecture on Decibels - what they are, and how they apply to amateur radio. His talk was illustrated with a PowerPoint lecture, which may be downloaded here.

Those CTARC members with grey hair had to scratch our heads (and watch what hair we have left turn even greyer) at the complexity of it all, having last had exposure to such mental calisthenics when at technical college or university (many years ago...)! At the time, John made it all appear so clear and simple!

John also showed us the tools of the pre-calculator epoch - logarithm tables and a slide rule. They may appear cumbersome to us now, but in experienced and adept hands they were tools of great productivity before cheap digital calculators became widely available.

Hans-Jurgen / ZS1HJH brought along a very useful card published by the German Funkamateur club, of a comparison between decibel values, Voltage and Power levels, and S-Units. He very kindly allowed us to make it available, so you can download it as a PDF file here.

Afterwards we broke for the usual natter over coffee and biscuits. All in all, another great CTARC meeting. We look forward to the forthcoming JOTA field station and October meeting.

Rob / ZS1SA opens the meeting and discusses forthcoming events

John / ZS1AGH begins his lecture

A series of calculations on a loooong sheet of paper!

John's lecture was ably illustrated by a Powerpoint show

The meeting was reasonably well attended, in spite of cold weather

Hans-Jurgen and Paul in discussion

Tea and biscuits and chewing the rag after the meeting