We held the June Shed Workshop a week earlier than usual on 26 May 2019. The event was held at Bernard ZL2BD’s QTH at 1 Winsley Tce, Churton Park, Wellington. The topic was Class D Audio Amplifiers. These audio amplifiers come very cheaply as modules and are incredibly small and light weight when combined with a switched mode power supply. They can also be scaled for different power outputs by simply changing the supply voltage. They have many good points, but there is a downside from an amateur radio perspective … they can generate a large amount of RF noise!
Bernard gave an excellent overview of the concept, the application and demonstrated the range of commercial modules available. His paper will be available here shortly to read.
The shed workshop was followed by a special afternoon tea at 2.30pm and then the AGM of RemoteDX Inc at 3pm. It was an excellent afternoon, with gorgeous late autumn weather.
At our shed workshop on Sunday 5 May, George ZL2AG opened up his garage and museum to the club to host the second shed workshop on vintage radios. The talk this time was given by Don ZL2BL.
Don first spoke about his restoration of a vintage Eddystone HF receiver. This had been somewhat hacked about by a previous owner, but he has restored it to near the status of the original.
He then talked about a couple of vintage AM radios – one he had restored and one still to be restored. They are illustrated in the photo below
George ZL2AG also had a mystery piece of electronic equipment for us to ponder on. This is clearly something developed for military or government purposes. Our guess is was that it is something like a range finder unit, since it is marked “E”, “N”, and “H” on the three banks of dials. Perhaps “East-West”, “North-South” and “High-Low”?
At our shed workshop in the afternoon of Saturday 13 April, George ZL2AG opened up his garage and museum to the club to host a workshop on vintage radios. We were intrigued by the progression in designs – from expensive crystal sets (with galenium cat’s whisker diodes, through to feedback designs like the TRF, before the age of superhets.
There were also changes also in the shape of cabinetry – from cathedral, through to tombstone and chest designs. George was lamenting the sharp fall off in interest in vintage radio, and was concerned about where all the beautifully restored vintage sets will end up. Tea and coffee was served at the conclusion of the workshop. A further workshop on vintage radios will take place in May.
On Saturday 9 March a shed workshop was held at the QTH of Mike ZL1AXG from 1pm – 3pm on the topic of test equipment. A number of speakers gave brief presentations (Mains power analyser and Vector Network Analyser by John ZL2JPM, a logic analyser by Kenneth ZS6KEN, a digital oscilloscope and spectrum analyser by Bernard ZL2BD, a Megger by Malcolm ZL2UDF, and analogue scopes by Don ZL2BL). This included a brief description of the purpose, indicative cost and tips and tricks in using the equipment. Eleven turned up and found plenty useful in the talks.