Now that Floyd, AAØGU, has his kit in hand (it took three days to arrive), I decided to start with the assembly. As with Heathkits, I sorted the parts in an egg carton,
and sat down to install the IC socket and the IC’s. At that point, KI0G (and the manual, and every suggestion on the listserver) suggest that you jump to section 3.55 of the manual and wind then install the T1 transformer. I had to wind a number of toroids for the Hardrock 50 amplifier I built last summer, and after a while developed a technique that involved sticking the core on a pencil . Unfortunately, that skill has atrophied and I don’t remember exactly how I did it. There are at least 5 YouTube videos on how to do it, and they’re all different.
You will find a lot of tips if you subscribe to the list server for the QRP Labs kits, which can be found here, at the ubiquitous groups.io. Unlike the older Yahoo groups list servers, this one has a very good search function, and I’ve used it several times. There are lots and lots of postings, though, so unless you don’t get enough junk email, you will probably want to opt out of receiving every one.
Before doing anything else, make sure that you have Version 4 of the PCB and the correct manual for Version 4. Then view one of the YouTube videos on how to build this kit. My favorite is by Mark, GØMGX, and you can view it here; the part on winding toroids and the dreaded T1 starts about 14:00 into the video.
The first problem in building T1 is the length of the wire. Enough is supplied to allow you to build an 80M kit, which requires a lot. The 20M version requires very little, but how much? It’s impractical to insert the wire through the toroid core using the whole length of the wire…but if you cut it, then what? The manual doesn’t say, but several hints in the list server directed me to http://toroids.info, which has a very handy chart that answers the question. The T1 core is a T50-2, and you need to install > 40 and < 50 turns. It calculated the length needed at 32 inches. I cut it to 33 inches. Turns out that’s not enough, if you intend to use the “loop” technique set out in the instructions. I should have cut it to about 43 inches.
I intend to strip the insulation off of the wire before soldering, and will try either a knife, or a very small wire stripper that ought to do the trick. If you want to borrow my wire stripper, let me know…