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Spider Coil ExamplesHere are some actual measurements of some coils that I have made. I will add to this table as I make more coils. These inductances are a little larger than you usually see. This is because I build the coils a little larger so I can take a little wire off if needed to trim the coil to the circuit. The lengths are in inches and feet A little note about my Q numbers: These numbers were reached using my unverified HP 4342A Q meter. Since I made the measurements on the same machine using the same methods, I will stand by the numbers inasmuch as they relate to one another. I do not make any claims of these being actual Q values. I have measured a limited number of coils using the old manual method that I used to use before getting the Q meter. They do fall in line with what I have measured on the HP. I do, however find that my numbers are in the ball park with others that have measured the Q of similar coils. So please take them on your own beliefs. L µH Thickness I.D. O.D. Litz Size Turns Length Q-1Mhz Cself 154 .125 2.25 3.50 40/44 40 32ft 330 4.7pF 248 .125 2.25 3.50 40/44 46 40 225 .125 1.75 3.50 40/44 56 38ft 340 3.5pF 248 .125 1.75 3.50 40/44 58 40ft 375 3.7pF 149 .125 2.25 4.75 100/45 39 33ft 540 6.3pF 238 .125 1.75 4.25 100/45 55 42ft 620 5.4pF 241 .125 2.25 4.75 100/45 49 42ft 620 5.4pF 146 .125 1.88 4.25 165/46 42 34ft 200 .125 1.88 4.25 165/46 48 38ft 220 .125 1.88 4.25 165/46 51 42ft 232 .125 1.75 4.75 165/46 55 44ft 750 4.0pF 250 .125 1.88 4.25 165/46 54 45ft 250 .125 2.25 4.75 165/46 49 45ft 155 .125 1.88 6 630/46 40 43ft 244 .125 1.88 7 630/46 49 62ft 150 .125 1.88 6 660/46 39 42ft 1000+ 4.7pF 241 .125 1.88 7 660/46 48 60ft 1000++ 3.0pF
Long Wave Coil A few weeks ago, while experimenting with the long wave coil I made for my 1625 tube all wave set, I discovered that I was able to hear some European broadcasters. Most of the time it was just hearing a heterodyne whistle, but I did clearly heard a station too. That is what it took to get me started on a dedicated long wave receiver. I needed a coil, and it had to be big. I had a styrene coil form left over from my first large styrene coils that I made. Since I had switched to a smaller hub (as well as an overall smaller coil), this form wasn't needed. I used 60/40 litz. That is, 60 strands of 40 gauge wire. 40 gauge works the best between 100 and 200 khz. My upcoming receiver design will be designed to work at 100 khz but should tune up to nearly 500 khz. My coil form is made from 1/16 inch (1,5mm) thick styrene material. The hub is 3 inches (7,6cm) in diameter. The width of the form is 7-3/4 inches (19,7cm). I wound 80 turns on the form, filling it nearly to capacity. The resulting inductance came out to be 992 microhenries. My target was 1000 µH. 81 or 82 turns would have done it! But close enough. We'll see how this works when the band opens again.
Date: 2016-01-14; view: 1277
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