I built this kit when it first hit the market years ago. The Chinglish instructions were terrible and contained several major connection errors. But, I got things sorted out and ended up with a pretty good antenna tuner. I had to replace the cheap poly vari-caps once after placing too much wattage through them (20-watts) but I suppose if you don't exceed about 10 watts in at a 50% duty cycle you won't have any problems. The seller at the time was moving a bunch of these things. I emailed that if he sent me another kit on his dime, I would build the second one while things were fresh in my mind, and write a correct English instruction manual as I proceeded. I figured it would be a pretty good deal - mostly for him since he had to be receiving a ton of customer complaints. He agreed but never sent the second kit and I didn't want to write the instructions strictly from memory. Still later, the market must have been flooded with these kits since for a period the price dropped to just a few dollars. So, I bought several of the kits and still have them except for the one I gave to a fellow ham. I never did build any more of the others and wouldn't want to since my memory of the problems has long since faded.
@DrAlNguyen
6 ай бұрын
Thank you for your contribution to the ham radio community. I'm pretty new at kit building and recently tackled my first homebrew , a 2 meter Pi-network antenna tuner that went pretty well. I was looking for a HF tuner and, as you mentioned, the price is pretty hard to beat. Without your very clearly explained video, I don't think I would have been able to successfully build this kit. Thanks! 73!
@bruceweight7319
2 жыл бұрын
Thanks again for the video. Due to your good video I got mine together and it seems to work pretty well. I was very careful not to overheat the terminals while soldering the core connected up. I did end up with one position that is catchy. I took your idea and used some smaller transformer wire and did all but the center pin of the rotary switch in that wire. It made it look pretty good.
@pendago8484
Ай бұрын
Thanx for this video. I got mine with no manual. Now I know how to build this kit correctly.
@mnpd3
10 күн бұрын
There's an online manual that has been around for years. But, the translation is bad and I remember a number of construction errors. I caught one by accident when I noticed that the photograph of the finished product's insides didn't match the instructions. That was some years ago so maybe things have been cleaned up. But you should be able to find the instructions through an online search... a ton of these things have been sold over the years.
@simonfoley4984
2 жыл бұрын
Thanks Carol .... Without yuor help I would not have realised that I wired the toroid the wrong way around !
@kp4md
2 жыл бұрын
I am glad to have assisted! :)
@MakeDoAndMend1
10 ай бұрын
Just made one of these chimese ATU low cost unit. Surprised how we'll it works. Thanks for your video .cheers from old George in the UK 🇬🇧
@quebirt
7 ай бұрын
Very helpful presentation. Thank you all, and thank you Carol. This makes these cheap little units useful.
@bruceweight7319
2 жыл бұрын
Hey I bought one of the ATU 100 Kit's that has the one big tune button and two extra buttons on for bypass mode the other button is to get manual tune mode or auto tune mode . I paid about twenty for the main board and all the components smd already installed and chip programmed. Had to wind coils etc. Solder relays and coils on. Only hard part was connecting the two aux switch lines. Paid 30 dollars for the case, got the one with Pl-259 connectors. Works fantastic. It does take about 5 watts to tune. There is things you can do to Chang it to a QRP only tuner.
@bruceweight7319
2 жыл бұрын
Thanks for the wonderful video. I am considering building one for my QCX transmitter and I am glad I watched you video. This is a very useful video. DE KB7CQ
@dracicidasempronius4754
2 ай бұрын
Im fixin to get one of these kits. Very helpful!!
@Soupie62
10 ай бұрын
A bargain buy, salvaged with some good sleuthing skills. Well done!
@kp4md
10 ай бұрын
Thank you!
@yuefei9887
2 жыл бұрын
Great Presentation, thank you for putting this information together and sharing it.
@kp4md
2 жыл бұрын
You're welcome
@billbates7810
5 ай бұрын
Nice clear video, I have built one but I didn’t encounter any issues, nut I did have heads up from a previous KZitem video some years ago. God bless, Bill G6ATO.
@quantumradio
10 ай бұрын
Thanks for the presentation. FYI it's not necessary to get the 2xM2.5 nuts. The provided nut, which is not M2.5, can work as a spacer right above the variable capacitor's lever (flat on two sides). The configuration that worked for me was (from top to bottom): M2.5 long screw>washer>(thread through the plastic knob)>washer>the provided nut (not M2.5 size)>screwed onto the variable capacitor. Tighten the M2.5 long screw and then the knobs turn the variable capacitors. 73!
@kp4md
10 ай бұрын
Thanks for your solution!
@robc3863
2 жыл бұрын
Great video, thanks, have just ordered one for my uSDX rig to use with a telescopic whip, hopefully it'll work well with your corrections! 73, Rob
@steveelectronics7819
Жыл бұрын
Given the argument about the placement of the 10 turn section of the inductor, why are the other taps at 1, 2, 2, 2, 4, 2, 3, 3, 2, 3, 2,10 Surely, following the same argument, taps at 1, 2, 2, 2, 2, 2, 3, 3, 3, 4,10 would provide the "finest" adjustment where it is required, gradually getting more and more coarse? Just for fun, I plan on making 2 of these, one with the documented taps and the other with the alternate taps that intuitively make sense to me.
@kp4md
Жыл бұрын
Your suggestion makes sense.
@twkolejofil
4 ай бұрын
I'm personalizing my kit now and I just thought the same. I use an aluminum case 10x10x5 cm (4x4x2 inches) with an additional switch for a general bypass and five others to switch between T/L/Π network
@PY2RKC-QRA-MIRO
Жыл бұрын
Saudações !!! acabo de verificar a PCI que recebi e o responsável corrigiu a serigrafia . TKS & 73 !!!
@zaicevnn
2 жыл бұрын
Спасибо Кэролл! Очень подробно и точно всё изложили, большой труд, спасибо! 73
@kp4md
2 жыл бұрын
Я рад, что помог тебе!
@ea6wu
5 ай бұрын
Thanks for the video!
@2yiz
2 жыл бұрын
Thanks for video I try to repair my tuner because not work before
@bruceweight7319
2 жыл бұрын
Very good. Thank you.
@bruceweight7319
2 жыл бұрын
One question that the diagram didnt seem to show but you pointed out and i wanted to make sure of. Does the wiper terminal and the tail end of the ten turn section go to ground; that was a point i am a bit confused by? I figured the wiper went to ground as you showed and the 10 turn tail end went to terminl 12 of the rotary switch. Otherwise what was the second ground wire on the ground wire? And again thanks so much for the wonderful video. I think most of the builders are still getting the torroid and rotary switch wrong.
@andyleatherbarrow7322
2 жыл бұрын
I just asked the same question. Is the end, ground? Did you figure this out?
@AdrieKooijman
Жыл бұрын
Having both the bottom end of the coil and the center contact of the switch to ground seems strange: you basically create a transformer with the secondary winding short circuited. The 4STUNER schematic reverses the connections, but also leaves one end of the coil open. I'm also not sure about if A having only one winding from signal to ground is any useful. 10 windings as minimum may be too much, only one seems very little even at 10 meter frequency. My gut feeling says: start with 3 or 4, and step up 2 windings per step until about D, make steps of 3 windings until H and increase the steps to 4 windings. This brings the total number of windings to 38, about the same as the original, but in my opinion with a more sensible distribution. (adding 4 windings to a coil of 20 or 2 windings to a coil of 6) update: I ended up to use 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4 windings (36 in total) windings and the first results look promising. More after I finish building my (tr)usdx.
@bruceweight7319
Жыл бұрын
I did ground the tail end. Mine works well. If you look at what the multi position switch does it makes sense. It keeps as someone else pointed out parasitic problems at bay. You can wind it anyway you like that's the stuff hams do. I just needed it to work and it does quite well. The center knob was a challenge but I got it
@bruceweight7319
Жыл бұрын
If you carefully watch the KP4MD Video you will discover that the diagram is backwards and the turn closest to the tee is somewhere around ten turns! That is wrong! It is something like one turn and then so on two ect. After the last turn of the ten turns it goes to ground. Each click gives you more and more inductance. If I had blindly followed the instructions it would not have worked and also the primary and secondary windings are backwards printed on the board. Many folks did not end up with a functioning LED if they followed the instructions that came with it. Again thanks KP4MD I think there were others who caught the LED mistake. I watched a number of videos before I built mine. I have been tempted to re-do the torroid again as I found a nice open non plastic rotary switch that won't melt when you solder it, also at one point I found brass extensions for the rotary capacitors that were made for just such a problem as the knobs. Mine cracked when I tightened them.
@kp4md
Жыл бұрын
@@andyleatherbarrow7322 Yes, the tuner exhibits high losses above 14 MHz with the end floating off ground. See photos.app.goo.gl/zY3cQaQDLFs2QU7U8
@dlabyer
Жыл бұрын
Will the swr indicator work at the one watt or less power range?
@carolf.milazzo3103
Жыл бұрын
Yes, I have seen the LED light with as little as 0.1 watt.
@andyleatherbarrow7322
2 жыл бұрын
Does the end of the inductor need to be grounded? some diagrams show it grounded, others not.
@kp4md
2 жыл бұрын
@andy leatherbarrow My schematic diagram shows the bottom end of the coil connected to ground. T-network tuners with air core inductors often short the unused coil turns that way to avoid undesired parasitic resonances in the free end of the coil. Some have reported that shorting the unused turns in this way may cause heating and power loss in toroid cores. When I disconnected the unused end of the coil from ground (floating), my tuner exhibited excessive insertion loss and failed to achieve an impedance match at frequencies above 14 MHz. See photos.app.goo.gl/zY3cQaQDLFs2QU7U8
@andyleatherbarrow7322
2 жыл бұрын
@@kp4md Thank you so much. I wound the toroid yesterday. My kit came with no documentation whatsoever, so your vid has been invaluable. 73 G8ZZF
@tmmlrd
5 ай бұрын
I built one without the coil reversal mod and in fact was not fully satisfied with the kit. Bought another kit and used the parts, including the box, to build a Z-match instead, which works very well. After the mod, can the T-match tune also high impedance antennas e.g. random wire or end fed or it can just tune antennas with, say,
@kp4md
5 ай бұрын
Yes, the corrected T-match does tune high-impedance and end fed antennas.
@stefanoranaldi2883
2 жыл бұрын
Thanks for your video very clear endeed
@TI3IES
2 жыл бұрын
Great video, thank you. I built one with the diagram published by the seller, with regular results, I will make another one with your instructions. I have a doubt, what each letter of the knob refers to, I have always asked myself and I have not found that information. 73, TI3IES
@kp4md
2 жыл бұрын
Ignacio, the letters "A" through "L" in order represent the increasing or decreasing values of inductance, depending on how you wire the switch. The letters help you to reset the inductor for a particular frequency. I posted the calculated inductance values in my photo album at photos.app.goo.gl/zY3cQaQDLFs2QU7U8
@Rob-ml7ps
2 жыл бұрын
Thanks for this. I bought one and started putting it together, but then saw your reverse toroid winding, but after i wound the toroid in the original way. I have a few questions. Do i need to wind it again starting with the 1 turn and ending in 10 turns? Does the other end of the enamel wire go to ground or leave unconnected? Which turns go to which number on the 12 pos switch (there are numbers on the back of switch)?
@kp4md
2 жыл бұрын
Hi Rob. No need to rewind the toroid. Just connect the end with one turn to the capacitors. Then either position "A" or "L" would be minimum inductance depending on how you wound it. My position "A" corresponds to one turn, or minimum inductance. My schematic diagram shows the far end of the coil connected to ground. T-network tuners with air core inductors usually wire the switch that way to short the unused coil turns and avoid parasitic resonances in the free end. There is some evidence that shorting the unused turns of toroid core inductors may cause core heating and power loss. I plan to check this in my tuner by comparing its performance with and without that ground connection to the inductor. Lifting that connection off ground is a trivial matter.
@Rob-ml7ps
2 жыл бұрын
@@kp4md Thanks. I've soldered it up now. I just found out the LED and BNC nuts are missing from the kit, so i have to go off and source those. Another question; I have a 40M QRP transceiver. Once i have this built can i simply attach a length of wire for 40M band, like for EFHW 84' long end fed and a 17' long counterpoise, to a BNC plug and use this tuner to tune it (no unun or anything else needed)? If that's the case maybe i can replace the antenna BNC with another style that allows me to screw down wire.
@kp4md
Жыл бұрын
If the coil end at switch position "L" is not connected to ground as in the original Chinese circuit diagram, the unused turns of the T network coil behave as an autotransformer. When the rotary switch selects few coil turns, a high voltage is induced at the free unused end of the coil. To test this effect, I temporarily connected a toggle switch between the unused end of the toroid coil and ground to compare the tuner insertion loss with it either grounded or floating. My observed results shows that tuner functions as desired over the 2-28 MHz frequency range when the lose end of the coil is grounded. When the unused end of the coil is disconnected from ground (floating), the tuner exhibits increasing insertion loss and fails to achieve an impedance match at frequencies above 14 MHz. For this reason, I connect the "bottom" of the T network inductor to ground to short out its unused turns.
@kp4md
Жыл бұрын
@@Rob-ml7ps Yes, you can use the tuner that way and use any type connector on its output.
@MakeDoAndMend1
10 ай бұрын
Ps your circuit diagram is wrong on the chinese atu it doesn't have a ground connection at the bottom of the 10 turns. It's the centre of switch is ground only. George
@kp4md
10 ай бұрын
George, you correctly noticed that change. Here is the reason: If the loose end of coil end at switch position "L" is not connected to ground as in the original Chinese circuit diagram, the unused turns of the T network coil behave as an autotransformer. When the rotary switch selects few coil turns, a high voltage is induced at the free unconnected end of the coil. To test this effect, I temporarily inserted a toggle switch between ground and the "bottom" end of the toroid coil at the "L" position switch contact 12 to compare the tuner insertion loss with it either grounded or floating above ground. The graph comparing the observed results shows that tuner functions as desired over the 2-28 MHz frequency range only when the loose end of the coil is grounded. When the unused end of the coil is disconnected from ground (floating), the tuner exhibits excessive insertion loss (>10 dB) and fails to achieve an impedance match at frequencies above 14 MHz. For this reason, I short the unused turns by connecting the "bottom" of the T network inductor to ground. My data is posted at photos.app.goo.gl/zY3cQaQDLFs2QU7U8 I would appreciate comparing with your findings. 73, Carol
@kp4md
10 ай бұрын
These alternative knobs appear to be usable with the 223p polyvaricon capacitors: 11:46 Knob + screw for 223p Variable Capacitor www.aliexpress.us/item/2251832461267835.html and Extension and Knob for Variable Capacitor www.mikeselectronicparts.com/product/extknob/
@georgealbertacanadaeh1038
2 жыл бұрын
Thanks. Purchased last summer started build today Jan 18,22. Really don't understand the wiring for the T106-2? is it 23 turns or 35 turns? George
@kp4md
2 жыл бұрын
Hi, George. There are a total of 36 turns on the T106-2 core. The numbers on the switch diagram are the number of turns between adjacent taps. The one turn at the top of the coil is between the first switch contact and the junction of the two variable capacitors.
@georgealbertacanadaeh1038
2 жыл бұрын
@@kp4md Thank you Can I ask a favor? Could you re draw for me showing the turns and where the taps are? as the drawing that came with this is very confusing? Thanks George
@kp4md
2 жыл бұрын
@@georgealbertacanadaeh1038 See the photos on arkadiam.github.io/transmissionlines/atu/qrp-antenna-tuner/
@kp4md
2 жыл бұрын
@@georgealbertacanadaeh1038 Scrape the enamel insulation off the ends of the wire loops in order to solder the taps to the switch contacts. Use the minimum possible soldering time to avoid melting the plastic switch body.
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