Shed Workshop 4 July – High Current Switch Mode PS and Mixers in the Simple TXCVR

Our July shed workshop was held on 4 July 2021 from 1pm to 3pm at the QTH of Mike ZL1AXG (2 Derry Hill, Churton Park, Wellington).

Mike ZL1AXG is building Charlie Morris ZL2CTM’s Simple SSB Transceiver.  This is a modular design and as each module is completed it is tested.   In this second session Mike discussed design and construction features and demonstrated the testing of completed modules.  The module in the picture is one of two double balanced mixers constructed from scratch on veroboard (Photo from Charlie ZL2CTM)

Bernard ZL2BD also presented on high current Switched Mode Power Supplies suitable for driving Kilowatt amplifiers.  He designed a system using two SMPS at 24 v to power a 2Kw linear for another amateur.  The SMPS turned out to be very quiet electrically and they are available in 12v and 13.8v and other voltages as well ex China at very reasonable prices. 

Tea and coffee were available following the workshop.

Shed Workshop 13 June: An antenna ecosystem and Constructing a simple SSB Transceiver

Controlling field equipment under an ecosystem approach

The June Shed Workshop was held a week later than usual – from 1pm to 3pm on Sunday 13 June 2021 at Mike ZL1AXG’s QTH due to Queen’s Birthday weekend getting in the way.

Mike ZL1AXG and Bernard ZL2BD gave an introduction to the concept of an antenna ecosystem, in which a range of antennas could be controlled by a single microprocessor control system.  This includes remote antenna switches (with just one antenna cable into the shack), 4 square switching, directional switching of beverage antennas or similar, tuning of magnetic loop antennas, and rotator control for beam antennas.

Mike ZL1AXG also introduced Charlie Morris’ Simple Transceiver for 80m SSB. He showed off some of the modules that are under construction, and outlined in a block diagram the design of the transceiver. He demonstrated how the audio modules could be tested using a multi-meter, signal generator and oscilloscope by inputing a signal from the signal generator at 1KHz in the front end of an amplifier and measuring the voltage on the oscilloscope or multimeter at the output end.