ZL2BD HV Magnetic Loop Butterfly Capacitor

The now very well regarded high voltage butterfly capacitor kit designed by Bernard Robbins ZL2BD will be launched by Branch 50 (Wellington) NZART in a couple of months time.

This will be your opportunity to acquire a butterfly capacitor suitable for an HF transmitting magnetic loop. The kit details and price will be available shortly, but enquiries can already be made to: tradingtable@zl2wb.com

Our shed workshop on 6 September 2020 will be an online Zoom session open to any amateur operator interesting in magnetic loop antennas. Bernard will be giving you all the details on transmitting magnetic loop antennas and he will demonstrate how to assemble the capacitor to make it easy for you to build the kit. It is dead simple to build!

Sunday 5 July: Hive Makerspace introduction and Demo by John ZL2XJ of the Nano-VNA

The programme for the afternoon meeting (1pm – 3pm at the Waitohi – Johnsonville Library) involved:

1] HIVE makerspace introduction and demonstration

Tūhura HIVE is the makerspace and sound studio, located on the lower ground floor of Johnsonville Library at the Waitohi Community Hub. It has facilities for:

  • 3D printing
  • 3D scanning
  • Laser cutting
  • Audio recording studio

One of the Makerspace Specialists gave a 30 minute introduction and discussion about the facilities available for Branch 50 member use.

The talk / walkthrough include a look over what is available in the Hive, A discussion of the objectives of the space, and some preliminary discussion on how we could use the space / get involved (either individually or as a group). This could be a good recruiting gdround for younger people interested in electronics.

The laser cutter, the 3D printers and possibly the 3D scanner (for replicating parts) would be of most interest to members.

2] For the second part of the afternoon John ZL2XJ gave a short talk / demonstration of the NanoVNA and the associated PC software tool to test filters and antennas.

The workshop finished at 2.45pm and several of us retired upstairs to Common Ground Café.

Active Magnetic Loops for low-noise receive

Rx only active magnetic loop antennas

On Sunday 7 June Bernard ZL2BD provided us with an onlie Zoom shed workshop talk on active RX magnetic loops. As with all of his presentations, this was well researched and he had experimented with 5 different loops in drawing his conclusions.

A report is available below, and a presentation and commentary will be made available shortly on this website.

Magnetic Loop Antennas in general have encountered a resurgence recently for Amateur Radio. A key attribute that seems to have been rediscovered by many is the small physical size of antennas for the 3.5 – 30 MHz HF bands. This makes them an attractive solution particularly in urban environments where space for antennas is quite restricted. Another important attribute is the improved signal to noise performance on receive compared to larger conventional wire antennas.

Using an Active Mag loop receive-only antenna is another variation of Mag Loops that provides the benefits of a low-noise receiving system without having to meet the stringent low ohms loop and high voltage tuning capacitor that is required for transmitting.

Branch 50/74 Lunch and Shed Workshop Event

On 1 March from 12 noon -3pm we met over a light lunch at Mike ZL1AXG’s QTH.

The Branch 50 NZART Committee ordered in a light finger-food lunch (savouries and sandwiches) as we were hosting Branch 74 for a combined branches event. Disappointingly, only two guests showed up … they were our guest speaker for the workshop, and one Branch 74 member! Mike noted that the year had not got off to a good start with few turning up for the combined branches BBQ organised by Kapiti Branch. It appears many amateurs simply don’t want to come out any more to events. However, complacency may well spell the end of amateur radio as we know it. Member attendances at most branches appear to be plummeting, even those that still have 100+ members on their books. Things are getting tougher for ham radio, with suburban QRM often sending the meter over s9 on the low bands, the sunspot cycle likely to be at its worst for some years, and Councils getting tougher in their district plans on amateur antennas (see the recent decision by Kapiti District Council).

It is likely that something radical will be required to breathe new life into our pastime. Maybe the new IC705? (just kidding!).

Putting aside the challenges for our hobby, our special guest presenter – Charlie Morris ZL2CTM – talked us through his approach to building homebrew transceivers. Charlie has built many working transceivers and uses them regularly, including on tramps into the bush.

Charlie Morris ZL2CTM talking about the two most important books needed by home constructors surrounded by a collection of homebrew txcvrs for 80m – 20m.

Charlie has a range of experimental radios using quite different techniques. They are mostly built inside Sistema lunch boxes, with full visibility of the “inner workings”. He has a global following of QRP and homebrew affiacondos who follow his latest creations. For example, check out his videos on Youtube and this review of an SDR design on Soldersmoke: http://soldersmoke.blogspot.com/2016/02/zl2ctms-teensy-sdr-ssb-superhet-very.html

Some wonderful hints were dropped, including a suggested order for constructing modules in the transceiver, how to use veroboard (matrix board) by placing all the components on one side of the board (the side with the tracks on it), how to bond a module to the ground plane so as to reduce the chances of unwanted feedback. Charlie also made a suggestion on how to switch the IF strip between TX and RX so you don’t crossover inputs and outputs using relays (hint: switch the mixer frequencies on your PLL device).

Charlie’s well received session ended with tea and coffee and a lot of chat amongst members with most members leaving around 3.45 pm. Charlie received many compliments and he provided a lot of stimulation for members. Maybe some of us will be buying those design manuals and building our own transceivers? For the Chair, it presents a challenge to move away (at least in the first stage) from a focus on getting the enclosure looking good, to coming up with new solutions to old problems by using a breadboard approach. i.e. it is time to use the box of processors being built up and have a play with a few IF strips, etc. Now if only there was time to do so!