Below are some photos of the event.
The meeting started with our chairman, Rob / ZS1SA welcoming us and reporting the sad event of two silent keys, Mike Rolfe / ZS1EW and Ozzie Elliott / ZS1NL, for whom a moment's silence was held. Rob then gave a brief report-back on the Lighthouse Weekend which was held at Green Point on the weekend of 15 / 16 August, and on our recent Committee Meeting of 17 August.
John / ZS1AGH (recent recipient of the SARL Jack Twine Award) will be giving a talk in a future CTARC meeting.
First up on the Show and Tell session was Mike / ZS1FP. He showed us two photos of a "Go-kit" mounted on a frame-pack for portability, constructed by Dennis / ZS1TC (thanks to ZS1TC for allowing us to reproduce those photos here). The rig is a Yaesu FT-857, powered by two 5 Amp/hour gell-cell batteries. The HF antenna is a multi-section whip, and the VHF/UHF antenna is a helical Rubber Duck. The setup includes and antenna tuner for HF matching to the whip.
Mike then showed us an adaptor that he built for testing equipment, consisting of a mains utility socket box with a (very well-) insulated loop on the Line circuit, around which a clamp meter can be fastened to make easy readings with the equipment in use.
Here Mike demonstrates how to use the clamp meter with the utility box to get a reading.
Mike also showed us another utility box which facilitiates plugging in of mains equipment with different formats of mains plugs.
Next on the list was Paul / ZS1S, who showed us some fascinating equipment. Paul's interest in high-end Hi Fi equipment (and very high-voltage electrostatic speakers) is evident in his Electrostatic DC High Voltage meter and Fluke HV probes he demonstrated. The electrostatic speakers (which deliver, apparently, phenomenal audio reproduction quality) are driven by a signal in the kiloVolt range (but with very little current).
Here Paul points out the Quad amplifier unit that is used to drive the speakers
These Fluke probes (as shown below) are needed to be able to measure the very high voltages involved.
Paul adjust the meter. At the rear of the unit is a metal rod that is drawn out and clicks into position at three points (corresponding to three voltage ranges to be measured). The rod connects to capacitive plates inside the meter, whiich when charged deflect the meter needle to provide a value.
Because the meter provides an infinitesmally small loading on the circuit being tested, it is possible to be highly accurate. The meter scale has an anti-parallax mirror. Paul managed to get a reading of several kilovolts from the HV power supply he brought to show us.
Next up was Hans-Jurgen / ZS1HJH, who showed us a very impressive, accurate, stable miniature HF oscillator kit that he built. The unit operates from 10 to 810 MHz. The circuit would be suitable for HF gear where, for example, the oscillator or exciter needs replacement (which is often the case, for example, in old military boatanchor rigs).
The block diagram of the oscillator. Note that it is not a Direct Digital Synthesis oscillator.
The frequency on the LCD readout display (accurate down to single Hertz level) is easily set by the rotary encoder to the right of the LCD. Rotate it and the Hz digits can be set. Press the button in the middle of the rotary encoder and you can similarly adjust the 10 Hz digits, Press the button again and you can set the 100 Hz digits, and so on, up into the 100 MHz digits. So neat!
The size of the oscillator unit is evident below, as Hans-Jurgen holds it between finger and thumb!
Next demonstration was by Nick / ZS1ZD, who demonstrated a JRC-NRD-545 DSP receiver, the last consumer communications receiver produced by the very excellent Japan Radio Company.
Covering 100 kHz to 30 MHz (and higher with the optional VHF/UHF converter), this particularly sensitive triple-conversion receiver can demodulate AM, AM-S, AM-ECSS, USB, LSB, RTTY, CW, FM, WFM & WFM-S modes. It provides continuously adjustable (in 10 Hz steps) passband filtering from as narrow as 100 Hz to almost as wide as 10 kHz. It offers switchable DSP noise reduction, narrow- and broadband noise blanking, tracking band-stop filtering and adjustable AGC time constants.1000 channels can be stored (each channel contains frequency, mode and filter settings) and scanned or swept through. Software control (offering theoretically limitless channels) via PC is an optional extra. (Because Nick couldn't take photos while doing his demo, we've used a substitute image here, courtesy of Universal Radio.)
Our chairman, Rob / ZS1SA had two things to show us: First was an ultra-miniature crystal-controlled (7 MHz) QRP CW transceiver kit that he managed to obtain and assemble. The kit comes with an etched, pre-drilled PC board, all essential components and could be assembled in an afternoon.
As is evident, the transceiver is very compact.
The kit comes with a parts list and component placement diagram. There is not too much to go wrong here.
Rob also showed us a trap from a trap dipole that he has built and used regularly. Using stainless-steel lugs it has lasted reasonably well after a couple of years up in the air.
Finally, Rob showed us all an example of a fine embroidered CTARC cap that John / ZS1AGH and his good lady Elsabe are taking orders for. You too can order one for a very reasonable fee, and have your name and callsign embroidered on the side.
And so another CTARC meeting came to an end. This had been a particularly interesting one. Afterwards, we all had the chance to chat with each other over tea, coffee and a particularly delicious cake very kindly supplied by Elsabe.
We do look forward to seeing you at the next meeting which will be held at the same venue on Saturday 26 September at 14h00. Details of this forthcoming meeting will be announced presently.
