Auto ATU

As a club project we decided to do the ATU 100 kit project. After studying for my exams and working on Learning Morse Code I’ve been a bit late to the party, but that did mean that I had the benefit of everyone else’s mistakes. This ATU works up to 100 Watts however has a minimum of about 10 Watts to actually tune up, I believe there are some changes that can be made in the software to alter the minimum power.

There are a few versions of this kit available on eBay, I was fortunate to chose one with the SMD already soldered in place, not all if the kits were like that, I have no experience with SMD so was pleased to avoid having to attempt it for the time being.

This was my first experience winding coils which was interesting but not too difficult, I used a drill bit to coil round and a Stanley knife to remove the enamel. After speaking to club members who had already finished the project I soldered the coils in first and then the relays rather than the other way round, I’m glad I did it this way round as the size of the coils would have made it tricky to fit them in afterwards.

When I first tried booting up I had an issue, the SWR wasn’t being improved much, or really at all by the Auto ATU despite it showing different L and C settings for each band when I tuned up… see if you can spot the issue?

Yes that’s right, 3 missing relays, no wonder it didn’t work! Once I added them in it worked very nicely.

I am pleased with this project and would recommend it for anyone looking for an ATU and wanting to try their hand at a fairly simple project.