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Well guys, totally lost it yesterday. Diasaster! Coil ends snapped but smarty pants here had glued them -- well I couldn't pick out the break. Went indoors very cross. Drank beer.
Today: Fresh start. Took jig to bits and cleaned it all. Inspiration: put a dowel in the middle, then spun the jig to wind the Rx coil - finger kept tension! Brilliant.
Repeat of Tx coil - fab!
Had to wind buck coil 'by hand', easy (so long as you DON'T glue the Rx coil first!!!)
2.4mV NULL - took an hour start to finish.
Moral: Patience, care. Lots of measuring AND note taking so you can follow what you are doing.
It is 4 degrees today so I am going to leave next part (potting etc) until it is warmer. What I now know is that you CAN make an excellent concentric coil if you are methodical, careful, and sober.
Dave Emery's article is a great start (but as I said, use plastic wall plugs insread of hooks so you can tune on the rig).
Eugene's advice is a must: keep checking and adjusting, a pain but vital.
Mold release DID work but I have another idea to try...
So its a VLF for the Bandio UmaxII: 8" coil. Rx tuned to 9.7Khz, Tx with buck gives 10.3Khz and I ain't messing with it to get down to 10.1, 10.3 should be fine!
I made the osc on a bit of vero, stuck on the jig, which made adj easy but when I hung the scope on the Rx it looked horrible. A 10k in parallel with 100n across the Rx more or less simulates the load and then it's fine.
Hope y'all find this interesting.
Today: Fresh start. Took jig to bits and cleaned it all. Inspiration: put a dowel in the middle, then spun the jig to wind the Rx coil - finger kept tension! Brilliant.
Repeat of Tx coil - fab!
Had to wind buck coil 'by hand', easy (so long as you DON'T glue the Rx coil first!!!)
2.4mV NULL - took an hour start to finish.
Moral: Patience, care. Lots of measuring AND note taking so you can follow what you are doing.
It is 4 degrees today so I am going to leave next part (potting etc) until it is warmer. What I now know is that you CAN make an excellent concentric coil if you are methodical, careful, and sober.
Dave Emery's article is a great start (but as I said, use plastic wall plugs insread of hooks so you can tune on the rig).
Eugene's advice is a must: keep checking and adjusting, a pain but vital.
Mold release DID work but I have another idea to try...
So its a VLF for the Bandio UmaxII: 8" coil. Rx tuned to 9.7Khz, Tx with buck gives 10.3Khz and I ain't messing with it to get down to 10.1, 10.3 should be fine!
I made the osc on a bit of vero, stuck on the jig, which made adj easy but when I hung the scope on the Rx it looked horrible. A 10k in parallel with 100n across the Rx more or less simulates the load and then it's fine.
Hope y'all find this interesting.