I buy a fair amount of electronics stuff from Amazon. Not big items, but stuff like BNC-to-binding post adapters and the SMA-BNC adapters for my HTs. So, I shouldn’t have been surprised when I got an email from them three weeks ago titled, “KKmoon ATU-100 DIY Kits…” The email included link to two ATU-100 antenna tuner kits, several assembled antenna tuners, and three QRP antenna tuner kits. See below.
I think that the ATU-100 kits look kind of cool. For about $50, you get a 100 W, automatic tuner kit.
My question, though, would be how effective and reliable are these antenna tuners? Has anyone purchased and used one of them? If so, perhaps you could get in touch with me, and we could do a short review.
KKmoon ATU-100 DIY Kits 1.8-50MHz ATU-100 Mini Automatic Antenna… $55.99
NOTE: A reader has reported that this link no longer works. If you go to Amazon, and search for “AT-100” you’ll find at least one other similiar kit.
SDRGEEK ATU-100 EXT 1.8-55MHz Automatic Antenna Tuner by N7DDC 7×7,…
$114.99
Zerone 1-30 Mhz Manual Antenna Tuner kit for HAM RADIO QRP DIY Kit
$16.99
Automatic Antenna Tuner,ATU-100 EXT 1.8-55MHz 100W Shortwave Mini…
$116.89
Vbestlife Automatic Antenna Tuner Aluminum Alloy Tester C Type…
$120.49
TecMad ATU-100 EXT 1.8-55MHz Automatic Antenna Tuner by N7DDC…
$115.99
HAM HF Band Radio Antenna Balun QRP Tuner Amateur DIY kit NXO-100
$17.99
HF Transceiver Kit Manual Antenna Tuner Tune DIY Precision Kit 1-30…
$22.49
WSDMAVIS 1 Set 1.8-50 MHz ATU-100 Automatic Antenna Tuner DIY Kits…
$48.29
Ed Jones K8MEJ says
I have not purchased any of these, or any ATU kits for that matter. However, the electronics are relatively simple and so long as the component choices are decent I wouldn’t worry too much. However, it would seem the most important thing is the microprocessor and logic to control how quickly it finds a match. For an ATU (versus a manual tuner), I’d also want to know how well the processor does at interfacing to radios to determine band changes. If these are user programmable all the better.
Casey KV3T says
This is the N7DCC design.
Bob, W6BP says
Some of these tuners are described as having been designed by N7DDC. I wonder if the companies marketing them have permission to produce and sell his design. (It’s a rhetorical question; I’m pretty sure I know the answer.)
Bilbo says
They are in the common domain, anybody can build and sell them as long as the originator is named and no changes to the design are made without publishing it.
Dan KB6NU says
Probably not. Can you give me a link to the N7DDC design?
Corey Mckay says
I believe this might be it on GitHub:
https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards
Ed W0OIC says
I purchased the tuner kit (ATU-100) on eBay at a much better price than on Amazon.
The tuner is excellent when properly assembled. That being said, the instructions for assembly are sorely lacking. Youtube video’s do have a couple of videos, but they could use some corrections. The relays should be put on the board last. The T1 transformer should be more detailed in the picture. Coils should be installed first with 7×7 relays going on last. A big improvement would be a complete part by part set of instructions. Wiring instructions are not detailed, but following the pictures does make it easy.
Lastly, the kit did not have operating instructions included and I had to go to Github to find them. You can smoke the unit if you try to tune it up with full power! Especially on 6 meters. Tuning power should not exceed 30 watts. It tunes fast and accurately and works exactly as described.
Ed W0OIC
Frank K4FMH says
Dan,
Because of your blog post, I looked into these ATUs. After watching a few YouTube comparisons, I bought this one but labeled as a different brand on eBay. Ed DD5LP has a similar one in your lineup.
Mine has firmware 3.1 and works well thus far with my FT-891. Not really tested it with various antennas yet.
Frank
https://www.amazon.com/gp/product/B08TMMDPB7?ref=em_1p_5_ti&ref_=pe_27541390_593408810
KK6RQ says
Who sells case/shell kits for those of us who bought the working board (w/SMA connectors) that comes w/.96 OLED and Dupont wires? I’ve found dozens of listings that come with SO-239 or BNC but nothing except fully assembled units that have my board and come with adapters for SO-239 and BNC. WTF?
Henrty Arndt says
I bought this tuner from AMAZON. I was amazed that the tuner was satisfied with a ratio of 2.0. Reports of toroidal cores getting too hot made me sit up and take notice. So I tried with an oscillograph to determine the phase angle as a function of the frequency. I was amazed that the maximum frequency was around 15MHz. At 28MHz the Q-factor was very poor (around Zero). I can only recommend replacing the toroids with yellow types. It’s always a lottery game to get quality cores, unfortunately.