ATU-100 Antenna Tuner Problems

In this video, we take a look at some of the problems I have encountered with the ATU-100 antenna tuner for ham radio.
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👉ATU-100 Antenna Tuner: www.amazon.com/dp/B099ZLVV3V/...
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[@lifegettingintheway2710]

My ATU-100 did not include the power-on options. So happy to see that is available. I also have the Z41 diodes and will swap them out for the 1N5711W diodes as they have better performance than the BAT41, and less capacitance. Really nice coverage of this topic.

[@TheSmokinApe]

Hey LGITW, that diode update should help. Thanks for watching the video 👍

[@rafaelgcpp]

The SA is a 1N5711W and E1 is the date code (January 2017), the other one seems to read Z41 and it is a BAT41. Each diode on its own is well suited for the application, but having different diodes will create different scales for the forward and reverse power metering. That is why on 1:1 it seems ok, but anything else is bad.

[@TheSmokinApe]

Hey Rafael, thanks for all the help!

[@rafaelgcpp]

@@TheSmokinApe my pleasure to help!

[@m7trsradio]

Thanks for the video Ape. I wouldn't know where to start. I have been looking at the At100m tuner to go with my Ft817 and made a doublet in the attic for home use. Great work dude Motters M7TRS 73 👍🏻

[@TheSmokinApe]

I have a second ATU100 to test but just haven't gotten to it yet, hopefully soon 👍

[@pcfreak1992]

I was considering this ATU and I I wasn't sure if I should save the money and get the kit or not waste my time for just a few bucks. But after seeing these videos from the inside, I get the impression that you kind of have to get the kit if you don't want it to be put together very poorly.

[@TheSmokinApe]

I am thinking you are right. I looked at the kit I have and it has two different diodes as well. Then I looked at the schematic and it says "D1, D2 - BAT41, 1N5711" meaning either diode should work. It looks like the are putting BAT41 in D1 and a 1N5711 in D2...

[@davidKD9WTA]

I have the kit which I still need to put together and would be great to see a comparison of both and see if same results.

[@TheSmokinApe]

Yeah, I need to get on the kit build. Thanks for watching David 👍

[@45auto]

Personally, I'd send it back and build the kit you have in hand. I'm of the mind that when you pay for an item that is complete than it should work out of the box. There are exceptions but this would not fit my criteria for fixing it myself.

[@TheSmokinApe]

I tend to agree with you 45

[@paulswartzendruber2881]

There are several ATU-100 models out there, all similar in appearance. I have been using an ATU-100 Pro+ for close to a year, now, with no problems on 80, 40, 30, 20, and 15 meters into a vertical with some pretty serious swr problems. I'm also using it between my Kenwood TS-430S and a Swan 1200X tube linear amplifier which has very poor input matching. I highly recommend this tuner, but make sure it is the Pro+ model.

[@TheSmokinApe]

Thanks for the info Paul, I wasn’t aware of the Pro+ 👍

[@zlamb]

the one i found just has an oled screen, tune button, power switch and is rechargeable. Is that it?

[@tomKZ8TOM]

I would like to see you do the kit. Do a photo comparison of the factory one and yours.

[@TheSmokinApe]

I think that's going to be the plan, that said my kit has the diode problem as well.

[@edmckinney8457]

Thank you ! I've been trying to get the one I purchased to work, with no success. It's now going back to Amazon.

[@TheSmokinApe]

Frustrating right?

[@edmckinney8457]

@@TheSmokinApe Not the first return to Amazon . But they always accept a return with no hassle

[@TheSmokinApe]

@@edmckinney8457 they make it easy for sure

[@ptarsob]

I've the same issue down here. Thanks a lot for sharing. Great video! I decide to rewind the tandem transformer and replace the diodes as you did (1N5711). My antenna is on top of an apartment building, a random wire with the sequence of a 1:1 choke balun and a 9:1 unun. I've tested the antenna with nanoVNA close to it. All Z values were ok for the ATU-100. My problem is: if my ATU ( my version is weather proof and can be installed outside close to antenna), With the ATU on 14th floor, and 38 m of RGC213, the tuning is almost perfect for all bands, from 80 to 10 m, with an exception ,1.8:1, on 20 m. But, when it seats close to the balun/unun, with a short (1.5 m of coaxial cable), the ATU is totally unreliable. It's useless! : ( Sometimes the unit enters on an infinite loop an never find the good combination. Then I change the radio to other band and come back to the previous one, it works ok. The case where it is mounted is plastic made bud shielded on internal side with copper foil adhesive tape. I'm giving up to use it close to the antenna! I'm lost. Anybody have an idea of what is going on?? Paulo PY1JDX

[@TheSmokinApe]

I stopped using mine, I should probably get it out an see what can be done.

[@don_n5skt]

My 500W works great so far. I should open it up and look at it.

[@TheSmokinApe]

I'll trade ya!

[@thomasmoore8142]

2 points: I don't think you can use resistors of any type to simulate a transmission line; wire wound are terrible, metal film are bad, and carbon would be best choice but probably would only work for null readings because the tuner normally only tunes the coax to show the reflected power and needs the complex impedance to make that work. I noticed that it takes a certain amount of power to make the thing work which can be changed by different windings on the Un-Un toroid (I just saw a you tube on it) so check to make sure you are feeding it enough watts.

[@LanceVK6LK_AussieHam]

Purely selfish comment from me but I’d like to see you repair the tuner. I’ve got one which isn’t playing nice too. I replaced both diodes with no joy. Interested to see if yours has a similar issue. Cheers and I really enjoy your vids and presentation style.

[@TheSmokinApe]

Hey Lance, the temptation to fix is strong so we will see...

[@chrisscott1547]

It appears that it's too sensitive on reflected power. Variations in reflectometer construction can cause this. There should be an R controlling this. One schematic shows this at 68K - you probably need more. Put a 100K trimpot in it's place and adjust it with the 6:1 load. I'll bet the 1.8 final tune value will come down too.

[@TheSmokinApe]

Hey Chris, thanks for the suggestion

[@SQ5TK]

My behaves almost exactly the same way as yours. Power readings and SWR are quite errating.

[@TheSmokinApe]

I'd check the diodes.

[@adventureswithpiper1045]

I built a Kit version of the tuner with OLED display. I too have this issue but only on 75/80 M. Also mine is the QRP version good for about 20 watts. The other issue I have with mine is that it won't tune at lower than roughly 5 watts. So its basically useless for QRP. My QRP rig puts out 1-3 watts on battery. Fun project to build and when it works it works ok but in my case its useless.

[@TheSmokinApe]

From what I understand, v3.2 of the firmware will tune with 1w.

[@AliReza-zx8km]

Nice.......

[@TheSmokinApe]

Thanks

[@mikeklungland8170]

I would send it back and test the new model, ATU-130. Would be interesting to see if it is any better.

[@TheSmokinApe]

I had no idea about the 130, thanks man 👍

[@davidbrowne1588]

Hi ape A lot of these tuners and the kit, have been made with the wrong diodes, I found with the wrong diodes fitted the reading got worse the higher you go in frequency, what are the new ones you have ? BAT 41, work well, But I think in your case you should look for a bad cap or inductor , or relay contact if it was working correctly before ? Dave 2E0DMB

[@TheSmokinApe]

Hey David, I looked at the kit I have and it has two different diodes as well. Then I looked at the schematic and it says "D1, D2 - BAT41, 1N5711" meaning either diode should work. It looks like the are putting BAT41 in D1 and a 1N5711 in D2...

[@davidbrowne1588]

@@TheSmokinApe Hi my board was ok on 40m and the reading for the power was getting worse on 20 and the higher I went the worse it got, so I changed both diodes to bat41 and all is good, the diodes are used to changed the voltage to DC before it goes into the pic controller, it is just that most have been fitted with silicone diodes that do not cover the HF frequency range, Also look at the tandem match transformer, as if that is damaged and is putting out to high voltage the swr will read higher than it should, Dave 2E0DMB

[@TheSmokinApe]

@@davidbrowne1588 that’s awesome, glad you got it sorted out 👍

[@emoisit]

Just wondering. I see the bag says "Metal Film Resistors" I thought we were not supposed to use that kind with RF. I thought it was supposed to be "carbon film". Am I not understanding that correctly? Interesting video. Thanks for posting.

[@TheSmokinApe]

I think you have that backwards. Metal film are more stable and less noisy, I think.

[@emoisit]

@@TheSmokinApe Maybe a video at a later date about why this resistor instead of that one for a dummy load. I have an old Drake DL300Dummy load Model 1550 and it say right on it Carbon. I'm not an expert at all so that is why I was asking. Thanks for the reply.

[@TheSmokinApe]

@@emoisit I’m no expert either, I crapped these because it’s what I had on hand. They were actually left over from a oil can dummy load project.

[@emoisit]

@@TheSmokinApe It has become an interesting avenue that I'm gonna have to do some research on now. LOL. Some of the stuff I have read before says that wire wound resistors have an inductive affect starting around 3-4MHz. Will have to learn something about the difference between carbon and metal film in ref to RF. Thanks.

[@mcgrath16511]

I say try the “fix”,, you still have the kit. Thing is, there is some pretty crappy cold looking solder joints there.. replace the diodes, reflow the solder lints.. and see what happens..

[@TheSmokinApe]

It's gonna need some loving to get it right...

[@mcgrath16511]

@@TheSmokinApe but look at the fun you could hav!

[@DonzLockz]

Geez, kids can't do soldering like they used to!😆 I think its better to start from scratch, they seem to be lacking quality control so there may be other issues apart from poor soldering.👍

[@TheSmokinApe]

I think that is the plan, thanks for watching Don.

[@Tump2010]

I would send it back and just build the kit, make a nice build video out of it.

[@TheSmokinApe]

You don't this fixing this one will be "fun"?

[@JReed305]

I just finished my kit. It wasn't to terrible as far as kits go, I say you build the kit then side by side compare them.

[@TheSmokinApe]

Glad to hear you got it built. So, here is where we are now…. I sent the tuner back and ordered a different one off AliExpress, I figured that of I was going to do surgery I should save 30$. I also have the kit I’m planning to build right after I get the problem with the MX-P50M amplifier sorted out. Lol

[@JReed305]

@@TheSmokinApe lol, hope you get the amp sorted out. Looking forward to seeing how the new tuner works out when you get it.

[@TheSmokinApe]

I have the kit and will probably start that soon. The Assembled one will be here toward the end of Feb 👍

[@JReed305]

@@TheSmokinApe Sweet! Looking forward to seeing how it works out for you. 👍

[@muppetpaster]

5:05 Paying close to fick-all for a auto tuner and expecting shiny solderjoints..😂😂😂 You get what you pay for is actually a thing in this world.

[@VU3HZW]

I have prefect 1:1 with a dummy load, however it's all screwed up once it's hook to my 40 Meter Inverter V. Now, I don't have any other instruments to dig into it.

[@TheSmokinApe]

I’d check to see if you have matching diodes

[@VU3HZW]

​@@TheSmokinApe I usually rely on this as a poor's SWR meter most of the time. My antenna was really bad and maybe the diodes couldn't handle it and died. Anyways it's just speculation for now. I will update you

[@TheSmokinApe]

@@VU3HZW good luck with it 👍

[@VU3HZW]

​@@TheSmokinApe I took help of someone who can work with these smd components. I explained him the issue. The tuner is work just fine @ 20 meters with 70 Watt. He don't have an antenna to test it on 40 Meters. Dummy loads is always perfect 1:1. Now, I am very confused 😢

[@markrobinson7831]

is the firmware 3.1 or 3.2?

[@TheSmokinApe]

3.2

[@skyblazer9137]

I got my ATU 100 EXT 2 weeks ago and it is working just fine on 10--11--12m. My SWR was over 7 on a new A-99 now all SWR is 1.19 highest and 1.02 lowest... KA1***

[@TheSmokinApe]

Hey SB, glad to hear it’s working for you 👍

[@LeeMcc_KI5YPR]

Hard to tell from the video, but the solder looks like it was done by a solder school dropout. Maybe Flux and retouch? Check to see if the diodes are still diodes?

[@TheSmokinApe]

Yeah, the solder is a mess.

[@germanjohn5626]

You sure you don't have a problem with the power of your rig folding back to a point where the ATU 100 doesn't have enough power to tune?

[@TheSmokinApe]

Not 100% but pretty sure, it will show incorrect SWR before it initiates the tune.

[@bassangler73]

I would send it back...Build your kit the right way

[@TheSmokinApe]

Thanks what I am thinking as well.

[@johnwest7993]

From China, I only buy kits, nothing pre-assembled. Then I check each component for functionality and measured value as I'm assembling the kits. Then I test the Hell out of them after I build them because I still assume I may need to change something to get them to work properly. It's really best to assume anything pre-built from China is defective or unsafe, and spend the time to go through it and make it right.

[@TheSmokinApe]

Hey John, thanks a good practice. I have the kit and it has the wrong diodes mounted on the board AND the new assembled ATU from China just showed up... maybe I will crack that one open on video and see what's doing.

[@johnwest7993]

@@TheSmokinApe, an excellent idea. With aspects of fixing old, free equipment, ham swap finds, fixing things that are breaking, not quite right, out of spec, and not doing quite what you want, making special programming or data cables, building kits and accessory circuits, adding convenient antenna switches, putting together a station desk and shelving for gear and whatnot to fit in the space you have available, my belief is that ultimately, a ham station is always something that's built, not bought. Only millionaires can truly 'buy' a ham station. And if they do, they've missed out on most of the fun of ham radio. Fundamentally, a ham station consists of more than a rig. It also contains books, hand tools, a soldering station, parts bins and some test gear.

[@temporarilyoffline]

I feel like the tuner could tune below 1.8, but it just gives up early.

[@TheSmokinApe]

And it won't tune the same way twice... lol...

[@falcon16czz]

Send it back too often poor workmanship is coming into America from China.

[@TheSmokinApe]

I about feel out of my chair when I saw the bottom of the board.

[@Andy2e0ree]

If it was me I’d do a full reset after you mess with mit

[@TheSmokinApe]

It seems to tune better after a reset but that makes the auto tune function pretty worthless.

[@paulreed8310]

Send it it back, electrics/soldering second rate and giving flucuating readings.

[@TheSmokinApe]

It's on it way back, thanks for watching Paul 👍

[@LeeMcc_KI5YPR]

"End fed half-wave dipole". I am confused. That's ok, happens to me a bunch.

[@TheSmokinApe]

Check this video Lee: kzbin.info/www/bejne/fKaQeaiYrq2DabM

[@LeeMcc_KI5YPR]

Thanks for the suggestion. In the video, you said, "End-fed half-wave DIPOLE", emphasis mine. When did an EFHW become a dipole? 🤔

[@TheSmokinApe]

@@LeeMcc_KI5YPR it’s technically a dipole that you end feed vs center or off center feed.

[@robertburdoff1789]

What does it owe you? your hard earned cash crying out "send back", challenge of the chase says "try to troubleshoot" lol.

[@krazyjojo1]

Personally I wouldn’t trust these tuners with my expensive equipment. That’s just me tho.

[@TheSmokinApe]

I can understand that perspective. Thanks for checking it out JP 👍

[@keysersmoze]

You don't use a tuner on a resonant antenna.

[@TheSmokinApe]

That’s right

[@paulm0hpd319]

A resonant antenna may not have an impedance close to 50ohms so would require matching of some sort

[@keysersmoze]

@@paulm0hpd319 Yes, you are right. I have been playing with nec2 antenna simulator. I look at the radiation pattern, then the complex impedance, then will there be a big enough inductance and capacitance in an atu100 to match it?

[@JohnTarbox]

Do the kit! Think about your issues with the current unit and the build quality. Is it like an iceberg where you only see some problems while others are hidden? Don't let this turn into a never-ending story. DE WA1KLI

[@tikicowboy]

Bummer, just got one after watching your previous video on this tuner ☹️ I guess I'll find out shortly if I have similar issues.

[@TheSmokinApe]

Well, you know where to check if its a problem.