Shed Workshop on 6 March: The ZC1 test jig & a replacement vibrator

For anybody who has been around in amateur radio for a while, the ZC1 will be well known. It was developed by Collier and Beale during WW2 for use by the NZ armed forces. As it covered both 80m and 40m, it was highly prized by hams, in an era when commercially made equipment was hard to come by.

On Sunday 6 March 2022 Bernard ZL2BD gave a talk (on Zoom) on a ZCI test jig that he built, and has used to test the working of several ZC1s. The club owns a ZC1 that is for sale to any member interested in purchasing it and was tested using this test jig.

Bernard also demonstrated a replacement vibrator that doesn’t require modification of the ZC1 power supply. He is still working on variants to perfect this.

11 members and visitors joined in on the Zoom session, which was very well received by those attending.

First Shed Workshop of 2022 – Xtal Filters

The Nano-VNA is a powerful tool for assessing the characteristics of all types of filters, including crystal bandpass filters. 

At the first shed workshop of 2022, Mike ZL1AXG discussed the construction of multiple crystal filters for HF rigs. This included a 12 MHz crystal filter for the Simple SSB 80m rig he is constructing in modular form (and this reflected the fifth presentation on that transceiver construction).

He also revealed a further 12 MHz filter and 2 filters at 4MHz for other  planned construction projects. In this workshop, Mike covered crystal selection, design options (including lattice filters in general and Cohn and QER filters) and the challenges of achieving a nice shape and a passband that doesn’t have too much ripple. 

He also demonstrated a “universal jig” for use with the nano-VNA and discussed when things go wrong with filters (in this case an LPF, or rather the test set up).

Final Shed Workshop for 2021: Portable MagLoop Tuner

John Moriarty ZL2JPM demonstrates his QRP portable mag loop antenna

Our final shed workshop session for the year was held on Sunday 5 December from 1pm – 3pm at John ZL2JPM’s QTH at 9 Ramphal Terrace in Khandallah.

John ZL2JPM talked in more detail about his portable microprocessor controlled QRP mag loop antenna that he briefly introduced to us at the October meeting. John won the annual Blackwood Cup for 2021 based on this entry.

7 November Shed Meeting

Our monthly shed meeting was held at Mike ZL1AXG’s QTH in Churton Park on Sunday 7 November. Two topics were covered:

  1. Receive magnetic loops
  2. Part 3 of the Simple SSB Transceiver series: Band pass and Low pass filters (Mike ZL1AXG)

Bernard ZL2BD gave an update on experiments with receive only magnetic loop antennas including the differences between tuned and untuned loops (See the attached paper) and Mike ZL1AXG talked about his recently acquired MLA30+ Rx loop that can be used in conjunction with the portable Tecsun PL-330 receiver.

Mike ZL1AXG also gave his third talk on the Simple SSB TXCVR. The talk covered construction and testing of band pass filters and low pass filters (See attached powerpoint presentation for more details).