There are a bunch of other parts on that board that might be nice to have too: lots of can inductors, good looking caps etc. May have to rip this thing down further yet.
So now with the key component in hand, I could really get this thing going. The design I used was featured on AD7BP's blog. It was originally designed by AA5TB.
As you can see, the design and construction are pretty foolproof. Here's my hacked together job:
I've got a 4.7kOhm resistor across the output for testing purposes and was pleased to find that I could get 1.3:1 SWR on 15-40m. Not too shabby! So I went ahead and boxed it all up nice and pretty and here's the end result:
Looks pretty sharp! I have not yet tried it on a real EFHW antenna but it does tune my doublet really well on 40m so apparently that is a pretty high impedance antenna there!
You might note that there is no SWR indicator on this tuner. After chatting with AD7BP, he said he didn't think you really need one and he's probably right. His argument is that the peak is so sharp that it is pretty easy to hear the SWR null and if you can get close enough, it will be within the tolerable range for most radios. In my brief testing, I found that to be the case but we'll see once we are using real wire!
Look for an update on the next portable outing!