By Simon M1BVX
At the G-QRP Convention at Rishworth School in October 2014, I managed to get to the last ½ hour of the presentation by Richard G3CWI, owner of Sotabeams. The title of Richard's talk was “Portable Operating” and his presentation inspired me to purchase one of the Adventure Lightweight Antenna Tuner kits marketed by Sotabeams. Why did I buy the kit and not the ready-built version? Well, I love tinkering with electronics and, although a total novice, I like making things and miss my meccano kits. I have built a couple of items in the past but the whole point of amateur radio for me is experimentation and building things not just playing with radios.
First impressions: - not a lot of parts to the kit but it looks simple to build. The components are well packed but there are no instructions included. Instead, a piece of paper gives you a web-site address from which to download the building instructions.
With all parts checked against the list in the instructions, let's get going!
The case was a black plastic case and, although I was very impressed with the laser etchings, I thought they needed to stand out more so I went for the option to screen print the case. I would point out at this stage I had not fully read the instructions and I wish I had as I got some paint bleed and had to clean it up a bit. This was my own fault and not the fault of the kit.
Here is the finished paint job – it's OK but a lot better than just black laser-cut panel.
The build is actually not that hard – the worst part was the toroid windings but after watching a few videos on YouTube I was away.
There are eight toroids to wind and they got better as I did more.
Then on to the soldering. I love doing soldering, maybe because I am a qualified Fusion Engineer (aka Welder, lol) but as I am in IT now, I have not done any welding for a while.
Next thing is to fix the toroids - here's the first three done which are fixed in place with nylon screws:-
The other five toroids are now fitted but need to be fixed down with hot-melt glue.
All together the construction took about 2 hours including winding the toroids. I have finished fixing the toroids with hot-melt glue, I have checked everything and now need to take it out and test it.
A final picture of the finished tuner:
I have given the tuner a quick test using a 55ft. long end wire. It's simple to use - all you do is flip the switches and turn the knob on the variable capacitor to get the LED as bright as possible. Easy!
The kit was easy to build, all the parts fitted as they should even the dip switches fitted with no problem. The only bit of trouble was the variable capacitor and its extension rod screw. I did not have any glue at the time and the screw did come loose. You also have to make sure the screw lines up with the hole and that you do not screw it down fully as it makes the capacitor harder to tune.
Everything about the kit in my opinion is good. I have never wound toroids before and as you start off with small windings first then build up to larger ones, if you take your time and watch some YouTube videos first it's actually very easy. You just have to make sure you take your time and do not rush. There is more than enough enamel-coated copper wire to wind them all and I had a bit left over. Also, don't worry about the long ends you have left after you have measured out the wire and wound the coil - you just cut the ends down when placing the toroids.
Overall, I am pleased with the tuner - I'm glad I purchased and built it and I very much enjoyed making this project.
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The Adventure Antenna Tuner is an L network tuner which is bi-directional so either side of the L network can be connected to the antenna or the radio. The tuner has a coax socket (BNC) and a pair of binding posts on both sides of the network. Wire antennas are easy to connect too via the screw-down binding posts or by using 4mm "banana plugs".
The inductance is provided with switched inductors giving a range of 0 - 5.6 uH in 0.1 uH steps. Hyper-bright LEDs indicate antenna current to aid tuning. They are in circuit all the time to give you reassurance that your system is working at peak efficiency. The typical matching range of the Adventure Tuner is 3.5 - 30 MHz.
The Adventure Antenna Tuner is rated at 20W peak (10W continuous) and weighs 175 g (6.2 oz.). The tough ABS case measures 130 x 68 mm (5.1 x 2.7 inches).
The Tuner is available either as a kit (£39.95 + P&P) or ready-built (£64.95 + P&P) from Sotabeams UK - see www.sotabeams.co.uk/adventure-tuner-kit-or-built. The 24-page instruction leaflet is available on-line at www.sotabeams.co.uk/content/Adventure Tuner Instructions.pdf.
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