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.
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.
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:
RFI in Amateur Radio: Brief overview of RFI (Bob ZL2AVM). Hams as the culprits!
RF interference tracking (John ZL2XJ). Diagnostic guide and detection tools.
RFI Suppression: (Bernard ZL2BD). SMPS Suppression and earthing
Everybody stayed around to enjoy the tea, coffee, sausage rolls and biscuits.
Bernard ZL2BD gave a talk on how to safely switch between RX and TX antennas on your rig and demonstrated the circuit (which is probably not suitable for break-in keying). This circuit would allow us to use our active antenna or mag loop antenna on RX and our standard antenna on TX. The MFJ unit above is an alternative approach.
He also demonstrated a simple phasing circuit that works with two RX antennas to reduce noise levels or to peak a signal. Steering of a two antenna array throughout 360 degree is possible. Two active antennas can be used, or in fact, any two antennas spaced less than 1/4 wavelength apart can be steered (on RX) to reduce unwanted noise and maximise forward gain.
The second shed workshop on Active Antennas involved a construction day … with soldering irons out and smoke from the burnt plastic wafting through John ZL2XY’s QTH.
The kit was made available to all Branch 50 NZART members wanting to build an active antenna. This involves two enclosures – the active RX unit at the antenna site – where the whip antenna is mounted and powered over coax, and the shack unit that provides for the power over coax. Assemblers found they were able to build about half of the circuit in the allotted time, and the rest will be done at their own QTH.
With the next shed workshop on 6 October 2019 at Bernard ZL2BD’s QTH will focus on antenna switching and phasing of two RX antennas to reduce or eliminate noise. This is a logical follow on and should be of heightened interest with club members getting their active RX working over coming weeks.