Category: News

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.

Class D amplifiers

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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”?

The shed workshop on Sunday 10 February was attended by five OMs. Several weren’t able to be present due to a conflict with the Vintage Radio Society. The conflicting time will be remedied for future shed workshops.

The topic for the workshop was provided by Bernard ZL2BD – an introduction to multimeter calibration.

Those attending the workshop brought along their multimeters and these were calibrated on the spot by those attending using an averaging method. Most of us were surprised how poorly the analogue meters (including an AVO) fared, and just how well our modern cheapie (and not so cheap) digital multimeters actually did.

A full report can be downloaded here:

Mulitmeter Calibration Workshop Report

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