Active Magnetic Loops for low-noise receive

Rx only active magnetic loop antennas

Join us on Sunday 7 June via Zoom to hear Bernard ZL2BD’s shed workshop talk on active RX magnetic loops.

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.

The shed talk using Zoom on Sunday 7 June will discuss construction of Active Mag Loops.

Email our secretary to be invited to join us on Zoom – this is not limited to club members. ALL ARE WELCOME. YOU SUPPLY THE TEA AND COFFEE!

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:

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!

Shed Workshop: Going portable with SOTA, POTA and Hidden Transmitter Hunts

SUNDAY 01 DEC 2019

The summer months have arrived so at our shed workshop we talked about opportunities to get out of the shack and go portable with SOTA, POTA, Fox Hunting, etc. The shed workshop was held at John ZL2XJ’s QTH on Sunday 1 December from 1300 to 1500 hours and was attended by 9 people.

Time to get out of the shack!

Our speakers, including special guest Wynne Morgan ZL2ATH, John ZL2XJ, Bernard ZL2BD and Kenneth ZS6KEN, covered SOTA (Summits on the Air), POTA (Parks on the Air), and Fox Hunting respectively. The discussion will be around equipment, locations, logistics, and involvement / teams.

At the meeting it was agreed that we would plan to get out and about with SOTA/POTA activations next year in the first weekend of February (or if weather is bad either of the following weekends) with multiple locations (Summits and/or Parks). We will also be putting in entries in the regional Fox Hunt at the combined branches BBQ on 26 January 2020.

Radio Frequency Interference: Shed Workshop

In a world of worsening noise floors, our workshop on RFI was eagerly awaited. Held on Sunday 3 November, from 1pm – 3pm at Bernard ZL2BD’s QTH (1 Winsley Tce, Churton Park) it was attended by 9 members.

Three speakers spoke about radio frequency interference. This is a growing problem for amateurs in urban environments and one that is not always easily able to be resolved.

The workshop was in three parts as follows:

  1. RFI in Amateur Radio: Brief overview of RFI (Bob ZL2AVM). Hams as the culprits!
  2. RF interference tracking (John ZL2XJ). Diagnostic guide and detection tools.
  3. RFI Suppression: (Bernard ZL2BD). SMPS Suppression and earthing

Everybody stayed around to enjoy the tea, coffee, sausage rolls and biscuits.