Next Expedition: VK5KI OC-139 22-28 July 2020

More antenna development: 30m 4-square early work

The team today undertook the first set of tests on the elements that will form the basis of our 30m 4-square array that we are planning on taking to Tonga!

The first challenge was to build one of the elements and validate the mechanical and the electrical characteristics. We were looking for a 50 ohm match point so that it would work properly with the 4-square array and were very happy when it matched almost spot on. We have left the radiator a bit long for now as when we add the other three elements we know the impedance will change.

We also make some more progress on adapting the CrankIR to cover 160-10m on a 12m Spiderbeam pole as well. More on that experiment in the coming week!

Testing 40m 4-Square Array in CQ WPX SSB 2019

Andy VK5AKH driving VK5GR in CQ WPX on the 4-square on 40m

The first major new antenna for the DXpedition has been completed and was taken out into the field for its first on air trials this weekend during the CQ WPX SSB contest.

The Array

Our 40m 4-square array, designed and built by Oly VK5XDX will take full legal power and then some. We verified that the directionality definitely works, being able to switch and see an immediate change in received signals between NA, EU and Asia across the contest. Unfortunately for now, switching involves going outside and replugging the antennas into different ports of the hybrid and phase shifter. We are looking at ways of building a relay switch box to add to the antenna so we can switch it back in the shack.

The array is supported by one of our equipment partners. The 75ohm phasing lines between the elements used cable sourced via Messi & Paoloni in Italy, who make foam based light weight coax that can still take the power needed on our station. This contributes to the whole array (minus the star droppers) weighing in at less than 14kg. It was designed to break down into lengths less than 1500mm so that it can be carried on commercial airlines as oversize baggage.

The Ultraflexx 7 50ohm main feeder used also came from M&P. This cable has roughly half the weight of traditional RG-8 – highly important for a weight limited expedition.

Results on the Air

During the contest, we were frequently asked what the antenna was and were complimented on our signals. We were happy to be able to often get stations in Europe and North America to reply with only 1-2 calls, and were pleased to be able to work some small pistol stations on 40m in the USA during the early evening (our time). It all bodes well for our 40m signal on Tonga in September!

A35JT gains a 4th team member – Welcome Steve VK5SFA

Steve VK5SFA operating VK5ARG portable in the Oceania DX Contest 2017

The A35JT team is pleased to have Steve VK5SFA join our expedition. Steve will be with us for the first week of the trip during the busy build period and the very busy operating period when we will be running both EME + HF (EME wont be workable in the second week due to sky noise).

Steve brings a wealth of amateur radio experience to the team. As an avid DXer and contest participant as well as his experience as a broadcast engineer he will be an invaluable member of our team. Welcome Steve!

You can now meet all of our team members on our Team page via our expedition website

Change of Callsign: We are now A35JT

Licence Received from Tonga

After several months of communications we have finally been issued with our licence to operate on Tonga!

We had a small surprise however when we looked at the issued callsign. It has now changed and our final assigned callsign is A35JT. Never mind!

We have also confirmed that we are not able to operate on 60m this trip. We have, however,  been granted access to 6m to conduct our EME experiments!

So after a quick rebrand of the website, QRZ and Facebook pages our identity is corrected and away we go!

Work on antennas continues

We have also been busy behind the scenes with Oly VK5XDX designing and testing our home brew 40m 4-square array. Weighing in at only 12kg the early tests are promising. We are hoping to run the array for part of the CQ WPX SSB contest at the end of March as a test.



Thanks to RF Solutions for your support!

The A35JT DXpedition team is indebted to Carsten VK4OA at RF Solutions for his support of our DXpedition. We have obtained a number of items needed for the DXPedition station through RF Solutions including some of the HYBRIFLEX-13 and ULTRAFLEXXX-7 feedline and connectors for the 6m EME station and the 40m 4-Square array. Team members have in the past also purchased RadioSports Headsets and SPE Amplifiers via his company.

Dealing with a local re-selller has been fantastic for solving customs import hassles and we would heartily recommend them for any VK or Pacific based Amateur Radio operators seeking products from the many brands of equipment that Carsten provides.

A35JT Azimuthal Map & Calling Procedures

Europe is Hard – we will be trying our best!

This map explains well the difficulties faced by stations in Europe working Tonga. Paths into Germany for example pass straight over either the North or South pole. That is why we are planning directional antennas and amplifiers for our activities targeting Europe. We are planning on establishing pilot stations in Europe to help us identify the best times for openings to that part of the world too. More on this soon.

Please respect our directed calls to specific regions!

We will always be working split frequencies and will use directed calling. We please ask stations in Asia and Japan to please stand by as we call for the much weaker European (EU) signals over the pole. We are hoping to arrange things so that only one of the two stations will be doing directed calling at a time so that if say 20m is open to Europe, we will provide a 30m signal at the same time to satisfy demand from Japan.

On FT8 we will also carry out directed calling – and will only answer stations from targeted areas when we have announced a particular call area. Note our FT8 operations will either be using the WSJT-X Fox and Hound mode or FT8 standard mode exclusively (not the other multi-thread variant that has recently appeared). We will announce our frequency plan closer to the expedition, as we need to coordinate with the ZK3 expedition on band usage.

Please note our QSO policy – we will accept calls from Oceania (VK/ZL/YB etc), Africa and South America at any time regardless of which region we are specifically calling, due to the relatively low numbers of stations active in those regions.

Stations in other regions, please understand – this is not to be taken as an opportunity to ignore the directed calling we are making for other regions at the same time.


Depending on the unique QSO counts, we may also call for ATNO (All Time New One) only. This is intended to give the small stations a chance to secure at least one contact with us.