My 1st post. Have a look at the K3NG ATU (Google K3NG TUNER). While he designed it as a balanced tuner, I have built an unbalanced version for around 20W or so. Using standard footprint 'cheap' relays. Actually the relays are the bugbear of an ATU, finding the right type and rating and low cost, since in this example there are 18 relays. From what I can see, latched relays are very expensive especially when you need 18. The trade-off is current draw, as per some posts here.
I used AD8307 Log detector chips in the SWR section. Caps used were 3kV rated 1812 sized smd although available in VK, might be harder to find in USA.
K3NG uses an Arduino NANO and a simple 2 line LCD module.? To keep size down, one of the 0.96" OLED displays might be a candidate.
glenn
vk3pe
