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.

CTARC Solar Noon Calculator - 4 April '18

John / ZS1AGH kindly sent us this useful link:

It is an online calculator for Solar Noon at your QTH.

Solar Noon is when the sun is at its highest and the shadow cast is at its shortest; the shadow should then be pointing directly North - South. Useful for aligning antennas accurately, if you don't have a GPS.

First obtain the Latitude and Longitude coordinates of your antenna's location (which you can acquire from Google Maps - just click on the exact point with your mouse and a label will appear with the selected location's decimal coordinates).

Then go to the Solar Noon web page [here]

Then plug in the Latitude and Longitude coordinates into the fields provided. Remember to set your time zone (as GMT +2 hours for local time).

Then the web page prints out a year's table with the exact Solar Noon times for each of the 365 days.

Below is an example of the process done for the CTARC clubhouse's (approximate) location:

CTARC Report-Back on September Meeting - 23 Sep '17

On Saturday, 23 September 2017, the Cape Town Amateur Radio Centre held its monthly meeting at the clubhouse in Rondebosch. Starting promptly at 14h00, our chairman, Rob / ZS1SA welcomed a gratifyingly full clubhouse to the meeting.

We had to start with the sad news of a silent key. OM Geoffrey Tyler / ZR1GFT, who passed away recently in hospital after a brief illness. A moments silence was held in memory of Geoff. We offer  our condolences to his widow, Val and her family. Geoff will be missed.

Rod then had the far happier task of handing over a club award to Richard / ZS1RIC, who won the Golden Wellie (for consistent club attendance through thick and thin). Richard had been unavailable at the July AGM when his award was announced.

Rob then gave a brief report-back on our recent Committee Meeting of last Monday, most of which had to do with progress in the repair and refurbishment of our club antennae. It will take several more work parties to get the club on air on HF. The intention is to get the A3S beam antenna up and running as soon as possible, to take advantage of various contests that are in the pipeline.

We also noted the recent Repeater Working Group meeting where Rassie / ZS1YT was elected chairman and CTARC club member John / ZS1EQ was elected vice-chairman there.

Rob also welcomed visitor Paulo / IU2EFB, visiting Cape Town from Italia. Paulo is in Sea Point at the moment and we hope to work him on air.

Then it was time for the main part of the meeting – Show and Tell.

Rob kicked off by showing us a very handy little cable tester that he built from a circuit in QST. It enables you to test coaxial cables for intermittents, shorts and open circuit, and is far handier than an ohmmeter. The circuit is very simple indeed, using just two LED's and a couple of SO-239 coaxial sockets. Rob also showed us his “chicken stick” -  a nifty device for safely discharging the large capacitors on a valve linear amplifier.

Rob was followed by Mike / ZS1FP. Mike showed us a very handy little power supply unit that he adapted from a broken one that he had found. Using a regulator and variable trimpots, he was able to convert it into one that has four switchable voltage outputs.

Mike also showed us a three-pin mains tester, using three neon tube indicators (two green and one red) that can show instantly whether a mains socket is correctly wired or not.

If that weren’t enough, Mike also showed us a canny tester he made that enables one to conveniently measure the current in a mains appliance by way of a clamp-on ammeter that clamps around an insulated single wire loop that extends from an insulated socket box.

Nick / ZS1ZD was next. He showed us a directional DF antenna that uses two loops (etched on a printed circuit board) in the same plane. It works on 144 Mhz / 2 metres. It has a small amplifier and detector circuit that drives a meter to indicate maximum signal. Sensitivity is deliberately reduced as one approaches the fox by way of three switchable ranges and a variable gain control, to obtain a proper null on the meter.

Tom / ZS1TA followed, with a demonstration of various things:

Firstly, he showed us PowerPoint slides of the noisy conditions at his QTH, especially on 40 and 80 metres. He shared with us his dealings with the municipal power authorities.

Then he showed us a solid project box for a homebrew azimuth-elevation control box that he started building some time ago.

Then he showed us an extensive series of SSTV images he has managed to send and receive by satellite using MMSTV.

Finally he showed us a project he is working on to control satellite tracking antennas with Arduino  / Rasberry Pi type of controllers.

Chris / ZS1CDG was next with two beautifully constructed projects. First was a morse code keyer that can send and read CW signals. Neatly constructed with an LCD readout. Then he also showed us a working milliWatt 10 metre band beacon that he has built. He demonstrated it live on one of the ham rigs in the shack. It transmits a repeating CW ID message.

ZS1AGH / John was next. He showed us an  app available for Android Smart phones for teaching morse code via the Koch method. This app, by IZ2UUF, can be downloaded and used by anyone with an Android smartphone.

Richard / ZS1RIC was up next. He showed us two mast constructions that are small-scale models for bigger ones that he has done as a project for other radio hams. The first is a winch arrangement for a coaxial mast, very similar in fact the the CTARC main mast which he constructed for our club. The second was an ingenious fold-over mast with a thrust bearing in the base, where the rotator may be positioned at the bottom of the mast, allowing easy access for maintenance. Both very well conceived and manufactured items.

Hans-Jurgen / ZS1HJH showed us a very fancy (and surprisingly inexpensive, for what it is) Software Defined Radio he obtained recently. The item, smaller than a pack of cigarettes, covers from 10 kHz up to 2 GHz, with a visible waterfall bandwidth (depending on the kind of computer you run it on) of up to 10 MHz continuous display and recording. Hans-Jurgen, who is no stranger to high-end specification and measurement, put the SDR through its paces and found it to be accurate in frequency to a few Hz at 1.5 GHz, and very accurate in terms of signal level measurement too. Later on he demo'd the unit with the accompanying SdrUno software, running on a PC tablet. Very impressive.

Noel / ZS1FW also showed off his homebrew code practice oscillator project that he built.

With the  Show and Tell section complete, we then held the raffle for the club’s Antenna Fund. Tickets had been on sale for R5-00 since the start of the meeting. Hylton / ZR1HPC managed the raffle and invited Paulo / IU2EFB to draw the winning ticket at random. The raffle was won by Tony / ZS1TK, who generously donated his portion of the takings back to the club. Thank, you, Tony!

The formal section of the meeting concluded, members then had the chance to chat over a cup of coffee and to buy and sell items at the Swop Shop. (ZS1SX, ZS1FP and ZS1TM all brought a variety of items along, and parted with some of them). The club still has a few bits and pieces available, which members will be able to peruse at our next meeting in October.

All in all a most interesting afternoon. Thanks to Rob for running the meeting, to all the participants who Showed and Told, and to all who attended.

Photos are here: Page 1  Page 2.

Our next main members meeting at the clubhouse will be on Saturday 28 October. More details to be announced on the bulletins, in Ragchew and here on this blogspot.

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 Report-Back of AGM - 24 Jul '16

On Saturday 23 July 2016, the Cape Town Amateur Radio Centre held its AGM at 14h00. In spite of some rather soggy winter weather, the meeting was well attended.

The meeting was opened by CTARC chairman Rob / ZS1SA, who welcomed members and visitors, and then delivered his Chairman's Report for the past year.

This was followed by the Secretary's Report by our well-organised secretary, Anne.

Our vice-chairman, Noel / ZS1FW, then read out the Treasurers Report on behalf of Danny / ZS1BL who was unable to attend the meeting.

Our chairman then had the pleasant job of handing over the Club Awards for the year.

The Golden Wellie Award (the Wellington boot is in fact black in colour), which celebrates that member whose attendance of club events (through rain, hail, sleet, snow, dust storms, hurricanes and other meteorological phenomena) has been most consistent, this year was awarded to Tony / ZS1TK.

The Club Participation Award, which is awarded for significant club involvement, assistance and participation, this year was awarded to Barry / ZS1FJ in absentia.

The Buck Taylor Trophy (the CTARC's top award) was awarded to Davey / ZR1FR for his extremely helpful and generous assistance of our club recently.

At this point, the chairman stood down and handed over the reigns to John / ZS1AGH while nominations for the post of club chairman and the committee were called for. The entire committee was re-elected, with Rob as chairman, for another year. The committee's details are [here].

The formalities now concluded, the club's members and visitors were asked to briefly assemble outside the clubhouse for a group photograph (see below).

Thereafter we returned to the clubhouse for a bowl (or two) of not one but two delicious varieties of hot soup kindly provided by Anne and Elsabe, as well as a glass of warming sherry for those who required a little further warming on that cold afternoon. A good opportunity to catch up and natter with friends then ensued.

Paul / ZS1S later on continued with some repair work to the antenna cable feed-in panel, which has been in need of refurbishment since our recent Antenna Work Party.

By about 16h45 the meeting had run its course and we made our way home.

Below are some photos of the event:

The quiet before the storm...
Anne & Elsabe await the arrival of the hungry masses

Rob / ZS1SA has just acquired a transformer,
Note the unique model of his car (next to the number plate)

Members settle down for the meeting

Rob / ZS1SA reads out the Chairmans Report. Throughout the event
the slide show from the 70th Anniversary celebration was projected

Anne delivers the Secretary's Report

Noel / ZS1FW delivers the Treasurer's Report

Tony / ZS1TK receives the Golden Wellie Award from Rob /  ZS1SA

Rob / ZS1SA announces the Club Participation Award for Barry /  ZS1FJ

Davey / ZR1FR receives the Buck Taylor Trophy from Rob / ZS1SA

John / ZS1AGH takes over as temporary club chairman while nominations
are received for chairman and committee and the voting takes place.

Rob / ZS1SA, our re-elected club chairman commits himself
and the committee to another year at the helm of the CTARC,
in service to the club's members

Group shot outside the clubhouse.
In the foreground is John / ZS1AGH'S prized Dart.

Left to right: Wolfgang /ZR1WHL, Hans-Jurgen /ZS1HJH, Mike /ZS1PE,
Noel /ZS1FW and Richard /ZS1RIC

Anne and Elsabe provided litres of very delicious soup!
(Chicken Noodle on the left, Butternut on the right)

And to keep the chill away there was a glass of sherry

Much discussion taking place after the AGM, as is always the case

Paul / ZS1S and Mike / ZS1FP.
In the background are Tony /  ZS1TM and Rob / ZS1SA

Gerald / ZS1GRM makes an emphatic point to John / ZS1AGH
and Geoff / ZR1GFT

Noel / ZS1FW and Charles / ZS1CJO

Wolfgang / ZR1WLH, Hans-Jurgen / ZS1HJH and Richard / ZS1RIC

CTARC Report-Back on January Meeting - 23 Jan '16

The Cape Town Amateur Radio Centre held it's monthly meeting at 14h00 on Saturday, January 23 2016 at the clubhouse.

At the meeting, Klaus / ZS1QO gave an interesting talk on various ham radio-related subjects including antenna hardware and the latest tuner from MFJ. The clubhouse was packed to capacity and the talk well  received.

John / ZS1AGH and Elsabe were there, selling CTARC regalia. You too can have your personalised embroidered  CTARC cap and / or T-shirt or golf shirt, all for very reasonable prices. John and Elsabe will be taking orders for these at subsequent CTARC meetings.

All members have been asked to check their information on the Members List that is pinned on the notice board re contact details and birthday dates, and to change and update their information if necessary: This is the new birthday list the CTARC Bulletin Readers will use. This information will also appear in Ragchew on each membeers' appropriate birthday month.

We look forward to the following meeting, which will be held on Saturday 27 February 2016 at 14h00 at the usual venue.

Klaus / ZS1QO in action!
Photo by kind courtesy of Rob / ZS1SA

ZS1CT Photos from the past - ZS1AGH

We gratefully  include these photographs, kindly supplied by John / ZS1AGH, from his formative years...