Automatic Antenna Tuner?

VK3ZYZ

Moderator
Has anyone got one of these Auto antenna tuners?
https://www.ebay.com.au/itm/254949869219 (kit under $40)
N7DCC_ATU.jpg
There are some good Youtube videos of them and I like this one showing the tuning of a 43feet long wire via a 9:1 BALUN
I'm hoping to get a kit and make one then install it just under the BALUN of my antenna to see how it goes.
Here is the source code. So far, I have not figured out how to use it, but there are those who can.
 

Attachments

VK3ZYZ

Moderator
The original has a 5W minimum input, with 10W recommended.
Here is a mod by K3SSG to use the ATU on QRP radios, and he shows it tuning on around 1 watt.
A change in the windings of one transformer and then exiting the hex file read from the original program on the PIC.
This could be fun to add into the case of my uBitX radio if I can get it working fully. Then with a battery, it would end up a very handy portable rig!
 

BillC

Active member
Hi Denys this seems to be an interesting article you might like to check it out . 80 m endfed wire antenna-n6pet.
 

VK3ZYZ

Moderator
There is a good auto tuner discussion on this qrz forum...
And page 3 has a picture on an ESP32(or8266??) remote controlled one by VK4HAT
That looks really interesting.
Here is his blog post..
and a video..
Check out his blog. lots of good stuff, as well as cakes :)
 

VK3ZYZ

Moderator
This guy built one and wanted to run the Nano VNA into it, but the levels are too low.
I wonder if the nano VNA could run a linear amp to get the power up enough for a full test?
 

BillC

Active member
I watched video Denys. He did not appear to have a 50 ohm load on the tuner output terminal . One would have thought that the tuner would "see" an load right through itself and that would have been reflected back to the VNA. , and then displayed as 50 ohms on the SMITH CHART. What we saw in the video was the VNA tracking the tuner all over the place while it was trying to find an impedance to match to . Another test might use a 40 ohm load or a 60 ohm load to test the tuner and VNA display, in that way we would possibly see a displacement on the SMITH CHART impedance line either side of the 50 ohm point. Wotcha reckon Denys.? Also be a bit wary about over driving the input of The mighty VNA., the mixer overloads easily and generates erroneous signals. I think the input should be - 20 dbm. Please check the specs on the VNA.
 

VK3ZYZ

Moderator
I'm trying to 3D print a case at the moment using some ABS filament. The problem is it warps easily,
Warped.jpg
and the 3D printer needs to be outside because of the fumes.
To try (again) to have a successful print, 40 lines of filament around the base has been added to try to keep it stuck down.
Also, it helps to keep it warm so a case around it is needed. A cardboard 3/4 box may help but a fully enclosed one is the way to go.
The ATU-100 works but I will need to up the tune power of the Hawk as it is marginal in level to complete the tune process.
 

BillC

Active member
Good Denys, is it possible to use an old electric iron to anneal the plastic and flatten it ,at about spit sizzle temperature, no steam.
 

VK3ZYZ

Moderator
Not really Bill.
This print would have been 3D, not just flat but i stopped it. It is the lid to a box, with pillars.
And the box too would warp so I have not carried on with the print as yet.
A few MDF sheets have been purchased in the hope of making a sealed cabinet to enclose the printer so there will not be a great temperature gradient over the print.
If this fails, I will just go on with PLA instead of the ABS, but there are 3 reels of ABS I would like to use up.
Stay tuned......
 
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