Hi Andrew (G0RVM) here… I really enjoy working HF portable due to a home that’s in a noisy urban conurbation and the joy of being out in the country, often with seriously impressive scenery all-around. This post is about my recent purchase, a MW0JZE constructed G3TXQ Hexbeam antenna.
Up to now I’ve been using simple wire antenna’s such as monoband dipoles and delta loops strung over or between portable fibreglass telescopic masts when operating portable. Due to the exceptionally low noise floors found at portable sites I can hear just about anything if its there, but its difficult to get heard due to the negligible gain of simple antenna’s. Enter the hexbeam, a 2-element Yagi for 6m, 10m, 12m, 15m, 17m and 20m giving useful forward gain (approx. 3 to 3.5dBd), a good front to back ratio and deep side nulls that should help during crowded band conditions. For example, a few years ago I planted a multi band vertical on the beach of a Scottish island. Yes, the antenna worked well, but it was just impossible because of very strong signals from all directions. Having some directivity and more importantly some useful nulls should greatly help.
Of course antenna beam pattern is not everything when operating portable; other significant considerations are the collapsed size, weight & portability, the erected size and finally ease of assembly/disassembly. The hexbeam scores highly on all these characteristics. Conscious that the Thornbury and South Gloucestershire Amateur Radio Club (TSGARC), my club, had a field weekend during May I decided to take the plunge and get a hexbeam in time for the event. The TSGARC as a 12m trailer tower so supporting the hex would not be a problem.
The hexbeam is not a complicated antenna and quite frankly I could make one myself, however, I wanted more than a prototype antenna, I wanted something that would cope with the vagaries of the English climate and was robust. i.e. it would stay dry in a wet English climate and would withstand multiple rounds of assembly/disassembly. Importantly, I wanted something which when arriving at a portable location was dependable. There are a few manufacturers of commercial hex beams and each seems to do a fixed and a portable variant. The portable versions are lighter and designed to fold. As my primary use was to be portable, a portable version seemed the right choice… However, I wanted something that was also robust and which could be erected full-time if I ever got a property where that should be possible. So I went for a fixed version!
After some Internet research I opted for one constructed by Anthony (MW0JZE) partly because of his good website, partly because of the excellent Youtube construction video’s but also because when we spoke he was very helpful and had experience of portable operations.
His antenna arrived in a cardboard box, inside everything was wrapped, even double and triple wrapped in news paper. Not quite what I expected and a real nuisance to unpack, but hey, you only unpack it once, the packing worked well and its eco-friendly – none of that plastic packing which is such a nightmare to dispose off 🙂 At home there is nowhere to assemble the antenna but I checked that the major components were present and just hoped the smaller bits and pieces (cable clips, nuts etc) were all present as I’d only find out for sure at the field event.
I need not have worried as everything was present, Anthony had even included some extra ‘wing-nuts’ as he knew my intention was to use it portable. So it was a warm, sunny Saturday when I constructed the antenna in a large field with plenty of space. From the outset I had a good feeling about the antenna as the build quality of the parts I’d seen at home was high. The fiberglass spreader arms fitted together perfectly, the arms into the baseplate and the radius and diameter cords just dropped into place. Anthony had obviously taken great care in its design and build.
As mentioned before, assembly was done in a field so it was a little disappointing that there were no hardcopy assembly instructions. Fortunately I had good Internet access via a TSGARC members cellphone and thus I could watch the assembly YouTube instructions. What would be really nice is if Anthony could supply the videos on a CD or include some instructions. Had Internet access not been possible, I’m confident I’d have worked it out, but having the reassurance was nice.
The antenna has a sexy blue engraved baseplate with ‘G3TXQ’ and a diagram of a hexbeam. It also has a large arrow with no associated text… I constructed the antenna as per the video’s (which didn’t show the arrow) but in haste I assumed the arrow indicated the forward direction of the antenna and thus mounted it to the tower so that the arrow pointed North. Wrong. If constructed as in the video’s the arrow points towards the back of the antenna 😉 Anyway, it was terribly easy to fix. Just a 180 degree rotation of the stub mast that fixed the rotor to the tower. This change took about 5 mins and that included lowering and raising the tower!
I purchased the toroidal choke balun with the antenna and this fixed to the centre post with a plastic clamp. There was a minor misalignment of its fixing holes but nothing a very slight enlargement of the fixing holes didn’t sort. On air, the antenna performed as expected; it demonstrated reasonable f/b ratio and good nulls to the sides. It was fed with around 400w and we received good reports from countries such as Japan, Argentina, Aruba, the USA, St. Helena Is to mention a few. So it worked and better than a wire dipole would have done I’m sure 😉 Perhaps next time I’ll do some side-by-side tests.
I pondered for some time the best way to dismantle the antenna at the end of the field event. I didn’t want to completely dismantle the antenna but only dismantle sufficiently to allow it to be packed and transported. It was actually a simpler problem than I had first thought. The element wires were disconnected from the centre post; the radius and diameter cords were disconnected; the spreader arms were disconnected from the base plate, the spreader arms were disconnected from each other and placed next to each other then finally all spreader arm parts were brought together in a neat pile. Finally the mass of spreader arms and element wires were dropped into a bag. The baseplate was left attached to the centre post. Next time it should be just a matter of getting it out the bag and reversing the process described above… Time will tell. 🙂
A good strong bag, something about 170cm long and 60cm in diameter with carry handles and compression straps would be an excellent addition 🙂
Thanks for the antenna Anthony, I’m really looking forward to using it again and perhaps performing a more scientific comparison with another antennas.
Andrew
G0RVM