Malahit ATU-100 Antenna Tuner DIY Kits 1.8-50MHz atu100 Automatic Antenna Tuner by N7DDC 7x7 0.96 Inch OLED SMT and chip soldered 3.2 Version Firmware Programmed Unassembled

I wanted a tuner to use with my FX-4CR that I had ordered. I ordered it while I was waiting for the radio to arrive.The kit arrived soon after I ordered it and well before the FX-4CR. I went ahead and built it in advance.Disclaimer, I am an experienced kit builder and built many kits of all sizes in the past. That said, this is not a first-time kit. It's not that it's difficult, it's that you have to build it with minimal instructions. About all you have is the toroid winding information and the screening on the board. But other than that, it's a pretty simple kit. Put in all the parts according to the screened locations on the board. Putting in all the relays is the biggest job. Then wind the toroids one at a time and put them on the board where each one goes. There is just enough information supplied to do that!The binocular core is the most confusing one, but following the pictures it's not hard to do.Use the supplied wires to connect the display paying attention to the pin names on both ends.I bought the matching enclosure and the board fit perfectly onto the threaded studs. The enclosure kit came with another display ass well as the coax connectors and some other parts, so I have an extra now. The buttons all mount on a small PC board, and the board is then wired to the connections on the tuner PCB.I only made one mistake wiring it up and it was of my own doing. I reversed the connections on one of the coax connectors so that the center pin went to ground. I spotted it quickly and it was easy to fix and caused no damage. I tried it out with my IC-7300 and it worked perfectly. So I put it away until the new radio arrived.The FX-4CR is a very small radio, but does put out 20 watts, which is why I got this tuner instead of the ATU-10. There doesn't seem to be much of a size penalty anyway. When the radio arrived, I tried them out together. I put a watt meter in line with them and worked with both a dummy load and various antennas. The tuner performed exactly as I expected and was able to match my 80M dipole on any frequency I tried.I am happy with the tuner so far and look forward to using it in the field with the FX-4CR.

Great little QRP antenna tuner, tunes just about any antenna. Shame it's only rated for 100 watts and to be honest, I don't it will handle more than 50 watts. As for building the kit goes, it's really easy, the only thing you will have trouble with is winding the binocular ferrite. I also recommend using some magnet wire for this, the plastic wire they give you will move out of place as you are winding it as where magnet wire will stay in place better. Don't waste money buying the matching case for it, find something else to put it in, save some money.

I FINALLY got this ATU-100 Antenna Tuner kit built after watching several YouTube videos done by previous builders. The Tuner works great but I had to re-work some wiring errors I made due to the lack of detailed instructions and the fact that I am not an Electronics Assembly Expert.The difficulty is that there are no detailed Step-By-Step Instructions for this kit. There is adequate information on the document along with the Schematic to enable an experienced kit builder to assemble the kit. However, a relatively new or first-time kit builder probably will not be able to get it assembled.Here are a few things I learned (some the hard way!) -Unless you have SUPER eyesight, use a large magnifying glass/light before you attempt to build this kit.1. For the Malahit ATU-100 Antenna Tuner Box, the image of the wiring on the back of the green TuneSwitch is incorrect. The wire connecting half of the Auto, BYP and Tune switches goes to GROUND, NOTthe + wire as shown in the picture that comes with the Tuner Box. The OTHER side of the Tune switchgets the + wire.2. The hookup wire necessary to fully assemble the ATU-100 kit does NOT come with the kit! You willhave to provide the stranded insulated hookup wire yourself (NOWHERE is this mentioned on AmazonNOR the single Instruction sheet!).A. I used some 18 ga. stranded insulated wire for the initial power connector but the hole in the PCBmade it tough to fit that size wire in the (-)hole. The other wire (+) goes to the On/Off Power Switchso there was no issue there.B. I used 22 ga. stranded insulated hookup wire (very flexible!) for the other hookup wire connectionsthat were necessary.C. The Yellow and White wires needed to connect the Auto and BYP switches to the BACK SIDE of thePrinted Circuit Board (PCB) must be VERY small to fit into the two tiny PCB holes they must besoldered into. You will need to be very careful soldering these two wires to the back of the PCBbecause the solder pads are so small and so close together!3. This is a very compact kit. Use a very small pointed Soldering Iron to prevent overheating the PCB orthe already installed SMD components.4. As another Amazon customer suggested, I recommend building and installing the Toroids FIRST (and intheir numbered order). Trying to install the Toroids AFTER the Relays are soldered onto the PCB will bea nightmare.5. Pay close attention to the size and LENGTH of the wire for each Toroid as stated on the Instructionsheet.6. As suggested in the instruction sheet, I used Allen Wrenches the proper diameter as described to windthe three air core windings.7. Take your time and be sure you understand EXACTLY where each component and wire should besoldered to the PCB. I initially soldered the four light yellow enamelled wires for the Tandem MatchTransformer "binocular" toroid in the WRONG 4 holes (underneath it!). They actually go into the fourSMALL holes just outside the "binocular" toroid's diagram outline on the PCB.8. The Electrolytic Capacitors have a very distinct mark on one side. Be sure that side of those Capacitorsgoes into the PCB hole that shows the white mark on the edge of the circle images on the PCB.9. Examine the picture of the vertically installed diode as it is shown on the Instruction sheet. Be sure thewhite ring mark is at the TOP when you solder it into the PCB (you will have to bend that end of thediode's terminal wire down toward the other wire end to install it vertically).10. If you buy the Tuner Box, BEFORE YOU SOLDER THE SLIP ON TERMINALS ONTO THE OLED, be sureyou draw yourself a diagram showing which terminal on the OLED display module is which connection(i.e., Gnd, VAC, SCL and SDA). After you solder the push-on terminals to the OLED display module, youwill no longer be able to read those markings on it!11. If you buy the Tuner Box pay close attention to how the four green mounting tabs are oriented in thepicture when they are attached to the PCB.12. If you buy the Tuner Box, when pushing the On/Off Power Switch into the end panel, do your best tokeep the switch even and press it straight into the rectangle hole (i.e., NOT one side in before theother!).13. If you buy the Tuner Box, I suggest sticking a piece of electrical tape or other insulation material ontothe back side of the front end panel. This tape will insulate the inside of the front box end panel. Thisis BETWEEN where the OLED display's soldered connectors are located and the inside ofthat box end. This should keep those solder connections from contacting the inside of that metal boxend. The Instruction sheet does not mention this. It just didn't make sense to me to risk those solderconnection points touching the metallic box end panel and potentially shorting out. I actually used asmall file to flatten the sharply pointed solder points to make their thickness narrower and less likelyto punch through the tape and contact the metal end panel.As I said, my completed ATU-100 Tuner works great! However, my language during the build process was not fit for human ears! I hope this was helpful to others considering to buy and build this kit and that they have a much better experience building their kit.73!

It’s not for the beginners and one must pay attention when winding the toroid cores and making the inductors, convert the mm to decimal for diameter and use a drill bit shank tge correct diameter to wind on.

Built the tuner, rather straight forward construction. Didn't tune! I did my normal trouble shooting and found bypass relay on all the time. Determined the program IC is defective.Contacted seller, wanted proof it was his device. Sent in pix's of board. Never got any comments back. So back it went to Amazon.Bottom line don't even think of buying from this seller, most dishonest.