A Tiny Tuner
Recently I’ve started to try out radios other than my KX2 and IC-705. Most of these small radios have no internal tuner, and while I often use a 17′ vertical that easily tunes for 20m, I also like to experiment with antennas.
Market Options
When I started my search I had a few requirements in mind.
- Portable
- BNC Connectors
- Kit
- SWR Meter or Indicator
There are several products on the market that fit this description so I started narrowing it down.
MFJ makes a few models that look nice, but my previous negative experience with the brand has left me apprehensive to buy from them again over quality control issues.
The Four States QRP Group makes a nice kit designed by Dave NM0S.
QRPGuys makes a 40m-10m Multi-Z Tuner Kit as well. I actually ordered this one first over a year ago and never received it. They did ship it, but I was in Saudi Arabia and it kind of slipped my mind.
EMTECH makes the popular ZM-2 which is available as a kit or pre-assembled, with either BNC or UHF connectors. It also has a nice set of binding posts and the ability to switch in some additional fixed capacitance values.
Kanga Products out of the UK also makes several fine kits and a few antenna tuners.
There are also some kits on eBay and possibly others out there that I missed. Drop me a line if you think I missed something important.
Kanga QRP Pocket Transmatch
Ultimately I decided on the Kanga QRP Pocket Transmatch. It’s very similar to their own Mini Transmatch, but in a different case and includes a switch for using balanced feedline setups. I ordered it on August 11th and it showed up about a week later. Total price was $85.45 U.S. dollars.
Assembly
The site cautions that assembly is challenging. The instructions are available on the product site to judge for yourself. The kit comes with everything you should need, except obviously tools, solder, and coffee. The parts are well organized and packed and the instructions are very clear. It includes a schematic and description of the circuit that make it easy to understand what is going on.
The first thing it has you do is wind the toroid. It’s a T68-2 with primary winding of 32 turns with two taps, and a secondary with 7 turns. Then you trim tin and solder to the PCB. The manual states that tinning the enamel wire was the hardest part, but I didn’t find it very difficult. As long as you have a decent iron and take your time it’s easy enough to just burn the enamel off.
After the toroid it’s a simple matter of populating the board with the through hole components. This does involve some trimming of the leads and some fiddly mounting of the variable capacitors but the instructions are very clear and make it very easy to follow.
I found the hardest part of the kit to be the final assembly. The case is very small and doesn’t leave much room for the BNC connectors and their connection to the board. I trimmed the leads as short as I could possibly make them while still being able to solder to the board. It took a bit of finagling to get everything to stay in place while the board and case were suspended and soldered together.
Operation
The controls are minimal and intuitive. Select balanced or unbalanced, set to operate then adjust the two controls until you have maximum noise on your radio. Then set to tune and key up while making final adjustments. You’ll know your spot on when the SWR led goes out.
Setting both controls to zero seems to almost bypass the tuner. I connected to a dummy load and had expected matches as I swept through the controls.
Verdict
Overall I highly recommend this little tuner. It was a fun build that wasn’t too crazy, and the range of match works great for everything I’ve tried so far. The picture above with the KX2 doesn’t do it justice for how small this really is. The size and weight are excellent and it seems to be durable enough for some mountain-topping. I’ll update this if it ever explodes though.
Do you have this or another tuner that you love or hate? Leave a comment and let me know!
72 – KK9U