Sunday, 24 September 2017

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.