#780

Episode 780
ATU-100 Antenna Tuner build and measurement. I try to look at the tuning on a VNA. I need to trick the SWR bridge. Also a bonus story time.
I did eventually build it all and try it out. It works as well as the internal tuner of the ICOM 7300. One of the downsides, it does not remember bands, so each time it has to auto tune.
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0:00 Beginning
4:50 Story Time
15:00 Wind Inductors
18:20 Turn on
22:50 VNA S11 Measurement

[@billpowell5931]

Pretty cool assembly and demo of how the ATU works. One of these may be in my future. Thanks. You have a quite colorful family history...

[@toddanonymous5295]

I usually fast forward through the soldering phase. Glad I didn't this time. You not only know electronics but are a good story teller . Very interesting and colorful granny .

[@PowderMill]

Masterful storytelling is always a treat on the IMSAI Guy channel. 👍🏻

[@K1ZEK]

I think I am hooked on story telling. You know we are going to expect a story every time now. HI HI 73 Leo. K

[@mcintoshtech8111]

loved the story about your gran ,great job on the build. thanks.

[@scharkalvin]

If you change the turns ratio on the SWR transformer, and reprogram some of the values in the EEPROM on the PIC (requires MPXIPE and a PicKit3 or 4, or an AVR (Microchip) ICE, you can get the ATU-100 to tune with only 1-3 watts of power. It's described in the builders manual, or on the website.

[@JohnSmith-bb2np]

I have one on my bench yet to be finished. I got as far as you and still need to add the last two buttons, and hook up the antenna connections to SO-239's in the enclosure already drilled and cut. It's almost there and been that way all this year. I would love to see the finished product in operation and any tweaks needed to work well. Thanks.

[@Tocsin-Bang]

I built one after the ready-built one I bought was a disaster. The one I built worked from the word go, into a dummy load on 100W it gave 1:1, and on my main end-fed it will tune to better than 1.5:1 on all the hf bands except topband! I had the same problem with the relays! Mine works down to 1.5W.

[@bruceweight7319]

Fun story and build/demo. Were there's configurable for QRP I ordered one and will be putting it together when it gets here. I really plan to use it for my portable station as a trimmer. I do have a SG-237 smart tuner/coupler. I like building stuff as well. Wasn't brave enough to get one where I had to do the SMD's

[@electronicengineer]

That's one heck of a crazy story you shared about your grandmother with getting into a bar fight and then marrying her opponent, under the condition of "leaving town" after a night in jail together! Wow... People sure are odd at times... LOL!!! Anyways, thanks for the great laugh IMSAI Guy! Fred

[@IMSAIGuy]

It made the local newspaper back then.

[@DonzLockz]

I came for the tuner but got mot more interested in your story about your grandmother! lol 👵 I think there are a few variations of this kit but it seems okay. Not sure but I think I want a tuner that was more advanced and more powerful as well as larger capacitors and inductors. I find your video's very easy to watch and understand.🍻👍🤓

[@gregmay9097]

Could you increase the SWR sense voltage to the processor either by more tuns on the sensing transformer T1/T2 or ad an op-amp to boost the voltage, maybe a combination of both, so that it is sensitive enough to see the output of the nanoVNA? How about reducing R3 & R4 and/or increasing/removing R20/R21?

[@M0UAW_IO83]

Might be interesting to fit LEDs across the relay coils

[@electronicengineer]

I agree, except it sounds (at least to me) as though the relay switching occurs at such a high/fast rate of speed, you might not be able to precisely determine what the actual relay switching "pattern" is, referencing the LEDs illumination, in real time. Perhaps with a slow mode video recording of the device with the LEDs connected together and the antenna tuner "doing its thing", with then the play back of the recording considerably slowed down... Interesting concept nonetheless! Fred

[@user-uv7ug1du4n]

Thank you for the nice experiment. My ATU-100 shows 10% lower power than the CN-801 SWR meter. So I tried to change the winding of the coupler from 1:10 turn to 1:11 turn, but no improvement. What should I do for the adjustment? 73 from 6M0MM

[@MYtimeNspace]

Question for you?? Do you think the capacitors in there are really rated for a high enough voltage to last?? thanks

[@joeteejoetee]

Trick'n it is "THE NEW" Hack'n it !!!

[@tabajaralabs]

you definitely should show that photo to us =D

[@jdmccorful]

So..?. Now , where would you use it? Interesting. Thanks for the look.

[@spillagonner]

I notice that the tuner is in "auto" mode, indicated by that dot next to "PWR 10W" Also, when you held the short across the button for a bit longer, the unit did a RESET rather than a TUNE. The button is B0, but there are also buttons B1 and B2, accessible on the back side of the pcb, along with A6 and A7, which are something to do with requesting TX for tuning. There is a video, linked on the N7DDC github page for modifying to accommodate QRP operation at 5W and less. Those additional buttons are needed for doing things like stepping through the inductors. I could use some help with any of that stuff.

[@NamasenITN]

Accepting the subsequent faulty readings, would a DC bias as you showed here be also suitable for a QRP radio input source?

[@jimcraig8754]

The chapters for this video list “Wind Inductors” but it skips from showing the cores to the inductors finished. It would be really helpful to beginners to show at least one of them being wound.

[@madcarew5168]

Let's see you with the surface mounts!!

[@IMSAIGuy]

kzbin.info/www/bejne/q6bdk5mFZbNkha8

[@IMSAIGuy]

kzbin.info/www/bejne/mJi3n3uebteke7s

[@IMSAIGuy]

kzbin.info/www/bejne/rYHRpXWJfLdkgMU

[@paulradulescu3069]

Thanks for the story and the banggood link .. ordered one, fyi. Hope they applied the referral. Checked your patreon lately?

[@IMSAIGuy]

Thanks. I'm new to the referral thing. I think I make 7% on purchases. Thanks for being a Patron. I have some very generous members. It helps offset some of the costs.

[@bruceweight7319]

We're the air inductors and the binocular core the explanation for the two different wire sizes. Also how did you size the air coils? Did you use drill bits for the size you needed?

[@IMSAIGuy]

the small wire is for bino core. the medium is for the smallest air. yes used a drill bit. These are not very critical, they just need to be close. the tuner tries combinations until the best is found.

[@WhoAmi-kt1qb]

just wanted to ask what gauge wire is the swr bridge that pig nose thing coz I need to order some as I buggerd mine up cheers great video

[@IMSAIGuy]

28 or 30 I think

[@kq6up]

There is a power on mode that allows you to step through all the values.

[@IMSAIGuy]

is there a document?

[@kq6up]

@@IMSAIGuy another youtuber demonstrates walking through it at the end of his video. kzbin.info/www/bejne/mJTalHeGipqDgrM

[@swenner64]

That is a sad story!

[@edisonchagas2796]

hello friend, i acquired the atu100 recently and realized that it marked roe and power outside the standards, so i decided to make some simple changes via pickit3 , when finished it didn't work anymore, can you guide me how do i get it to turn on again?

[@IMSAIGuy]

sorry, can't help you

[@johnwest7993]

Best video yet! Tell more stories. :) A couple of questions: At what SWR reading does it autotune? It looked from the video like somewhere around 1.7 to 1. I'm also curious what degree of signal attenuation there is when all (or most) of the toroids are switched into the circuit. These aren't roller inductors, so I suspect it's significant. I've watched half a dozen videos about these units and have learned essentially nothing of value from the other videos. The other KZbinrs don't seem to understand what they are doing and what matters, or even how an ATU works. KZbin videos. Sigh. But thank you for your videos. They are the good stuff. As random as they may appear to some, they knowledgeably cover many of the topics and devices I am most interested in. And the stories are a great distraction while you are doing repetitive soldering and assembly tasks.

[@chickenjoymanok1]

how do you connect the led pins ? thats my problem right now

[@9V1SA]

I notice that manual QRP tuners like the Emtech ZM-2 have a tune mode that makes sure a transmitter is always presented with a safe load impedance even while the tuning is being adjusted. Is that the case with this auto tuner design also? I ask as some commenters in the QRP labs groups suggest it’s common for these auto tuners to present transient wildly high VSWR while they are doing their search for a match and that has been blamed for blowing up the PA on simple unprotected rigs like the QRP labs QDX.

[@gaurav279]

Hi Thanks for sharing the great video. Can you pls guide how to connect the 4 pins on the OLED LCD to the main board. 73s De VU3OSA Gaurav INDIA

[@frankowalker4662]

Your poor granny. She sounds like she was a bit of a character. :)

[@benotsilent6703]

These have a test mode where you can manually step through settings.

[@JohnTarbox]

This is definitely much cheaper than most other ATUs. I think I will get one to use with my IC-705. Are you planning on doing some measurements of efficiency?

[@IMSAIGuy]

no, it will be the same as any internal tuner

[@JohnTarbox]

@@IMSAIGuy The efficiency I am talking about is what percentage of the power punt into the tuner is actually delivered to the output and not lost in heat, etc. All tuners, manual, automatic, or whatever will have some loss.

[@IMSAIGuy]

@@JohnTarbox Yes, understood your question. It will be about the same as any radio with an internal tuner. the design is the same. The losses are quite small

[@davidfainitski4201]

New QRP tuner for IC 705 here kzbin.info/www/bejne/pZLRenaop7isfKc

[@rickwise9910]

It's nice that you like building kits. If only you knew how to solder... :-)

[@IMSAIGuy]

I'm working on it....

[@bruceweight7319]

I believe there is a menu where you can step tune it

[@mauriciotaslik4205]

You didn't need to trick anything! You could just have used the "test mode" and trigger all relays manually as you wished.... nice hacking experience though :)

[@toddanonymous5295]

P.S. My son watches your videos but my grandson doesn't. I will refer him later. He starts school in 2024.

[@nickcaruso]

Binocular core?

[@johnm7723]

One of the ferrites looks like a pair of nostrils or binoculars, the windings pass through both 'tunnels'.

[@TheRetiredtech]

Binocular core

[@TheRetiredtech]

My Grandfather was murdered in Kansas City, Mo. In the early 1900's.

[@TeslaTales59]

we like "story time" I just built a Velleman "brain game" You might like this one too

[@TheRetiredtech]

I know this is old but this tuner will single step..

[@JohnTarbox]

How is this working for you? It has been reported that the diodes used in the SWR bridge that are shipped from China are sub-par and that the performance can be improved by substituting good quality Schottky diodes. Have you considered this? github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards/issues/61#issuecomment-873661548

[@IMSAIGuy]

I didn't really need it as the IC7300 has a built in tuner that I use. I did put it on the air and seemed to work just as good. It does not remember so always has to hunt for second. then ok. since you are just looking for a minimum SWR, the diodes are not really critical. if you use it for a calibrated power meter (I did not) then maybe better diodes might be a difference.