Summary

This is a box for tuner kit you can download the datasheet here
https://app.box.com/s/so3ov9b0zjsz3dysj1s9/1/1331269728/11820041217/1

http://m1kta-qrp.blogspot.com/2014/05/comments-on-chinese-atu.html

or buy a kit on ebay or other seller
"QRP manual days Antenna Tuner Diy Kit 1 - 30 Mhz For HAM RADIO"

I add a Antenna Centre + 1:1 Balun inside
https://www.sotabeams.co.uk/antenna-centre-1-1-balun/
datasheet here:
https://www.sotabeams.co.uk/content/HF%20Balun%20Kit%20Instructions.pdf

the think is not perfect, we must carefully adjust the screw holes for M3 tapping

73
F4EGX