Eric Foster: My Beachscan uses a coil of 1mH as does the C.Scope CS7 and CS6PI. ========= White's Spectrum Rx 1,2 36mH 123 ohms Tx 4,5 540uH 1.4 ohms ======== White's 6B Rx 1,2 16mH 35 ohms Tx 4,5 1.7mH 7 ohms ========= White's DFX concentric Rx 1,2 13.8mH 36 ohms Tx 4,5 540uH 2.7 ohms ========== White's DFX DD Rx 1,2 14.2mH 55 ohms Tx 4,5 680uH 3.5 ohms ========== Tesoro concentric Rx 3,4 6.2mH 22 ohms Tx 1,5 5.7mH 22 ohms ========== Tesoro early Lobo DD Rx 1,3 1.35mH 12 ohms Tx 2,4 10mH 55 ohms ========== Fisher CZ Rx 1,2 6.8mH 30 ohms Tx 3,4 1mH 2.8 ohms ========= XLT 9.5" TX: L=540uH R=1.4 ohms RX: L=36mH R=122.8 ohms ========== Fisher 1210 Rx 6,48mH / 15,3 Ohm Tx (1,64mH / 7,7Ohm) + (1,62mH / 7,5Ohm) ========== Fisher 1266 Rx 10-10,4mH / 38,2-39,3 Ohm Tx 2,14-2,2mH / 4,7-4,9 Ohm ========== Fisher Quick Silver Rx 6,69-6,7mH / 31-32Ohm Tx 0,945-0,960mH / 3-3,1Ohm ======== Fisher Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ CZ7 5" 973uH 2.65 --- --- 6.85mH 25.6 --- --- CZ7 8" 968uH 2.81 --- --- 6.81mH 31.5 --- --- CZ7 10" 949uH 2.88 --- --- 6.73mH 29.4 --- --- CZ6 10" 2.44mH 4.80 --- --- 10.97mH 39.1 --- ========= Garrett Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ BFO 12x24 120.9uH 3.22 --- --- BFO 24x24 115.0uH 3.24 --- --- XL500 7" 149.5uH 1.2 --- --- XL500 12.5" 140.8uH 0.746 --- --- SeaHunter MkII 8" 118.6uH 1.18 --- --- SeaHunter MkII 10x14 107.2uH 1.38 --- ====== ======= Minelab Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ Explorer 10" 581uH 0.88 --- --- 472uH 5.9 --- ======== BBS 1000 10" TX? (1,2): L=1.022mH R=26.6 WOT 15" (Sov) TX? (1,2): L=1.042uH R=22.7 Excelerator E 18" (Explorer) RX (1,2): L=653uH R=17 TX (3,4): L=366uH R=7.75 ========= Troy Shadow Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ X2 S-9 9" 5.72mH 23.6 --- --- 6.25mH 25.2 --- --- X5 7" 1.067mH 4.33 --- --- 6.53mH 32.2 --- --- X5 9" 1.044mH 4.45 --- --- 6.50mH 32.7 --- X5 1.1mH / selfres = 255kHz 6.5mH / selfres = 87kHz ======== Tesoro Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ Tesoro Brown 8" 5.59mH 21.2 --- --- 6.23mH 22.1 --- --- White 8" 5.68mH 21.8 --- --- 6.36mH 22.8 --- --- White 4" 5.62mH 26.6 --- --- 6.13mH 28.2 --- --- uMax 9x8 5.74mH 24.6 --- --- 6.21mH 25.8 --- --- uMax 12x10 5.78mH 17.3 --- --- 6.15mH 18.9 --- --- Lobo 5x10 9.93mH 50.5 --- --- 1.33mH 10.97 --- --- Lobo 8x15 10.52mH 62.8 --- --- 1.37mH 13.13 --- --- DD 11" 5.90mH 19.8 --- --- 5.38mH 18.4 --- --- Sandshark 8" 358uH 11.0 --- --- Sandshark 10" 358uH 11.0 --- --- Sandshark 5x10 357uH 7.38 --- ========= ========= White's Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ 6B 4" 1.74mH 7.71 --- --- 19.7mH 35.1 --- --- 6B 8" 1.72mH 6.47 --- --- 12.92mH 32.2 --- --- 6B 10" 1.69mH 6.68 --- --- 16.2mH 39.1 --- --- 6B 15" 1.59mH 6.36 --- --- 21.0mH 51.5 --- --- Spectrum 9.5" 540uH 1.40 --- --- 36mH 122.8 --- --- DFX 9.5" 540uH 2.67 --- --- 13.79mH 35.8 --- --- Eclipse 5.3" 554uH 2.76 --- --- 14.01mH 31.1 --- --- Eclipse 6x10 678uH 3.51 --- --- 14.19mH 54.6 --- --- Bigfoot (XLT) 554uH 1.81 --- --- 43.0mH 146.7 --- --- SM PI Pro 9.5" 230uH 1.37 --- ======== Barracuda Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire ________________________________________ Barracuda 8" 545uH 1.24 --- =========== Concentric - 6, 9, 11, 12, 14, 16 DD - 6, 9, 11, 12, 14, 16, 18, 20 Elliptical (DD or Mono) - 4x6, 6x9, 8x12, 10x15, 12x18, 15x18, 16x20 Mono - 6, 9, 11, 12, 14, 16 Rectangular (DD or Mono) - 3x12, 4x16, 5x18 Material - .060 thick ABS (before forming) Color - White or Black (white is better for beach/water hunting) Ears - .250x3 ID Ear Spacing - .900 / .750 / .720 Cable Flex Fitting - Sealcon (includes fitting, nut, and o-ring) two sizes available to fit cable OD .11 to .26 and .16 to .31 Also tried from 6.35 to 6.55 kHz. Works just fine! 396 windings (RX), 31 windings(TX) and 11 windings (Feedback)... 21.5 cm coil, conventional White's coil... this is whites concentric coil L1 - transmiting L2-feedback L3 - reciving L1 inside diameter is 6.375inch with 85 windings of 0.36mm wire(width of windings is 0.188inch) L2 inside diameter is 3.937 inch with 27 windings of 0.36mm wire L3 inside diameter is 3.188 inch with 275 windings of 0.23mm wire(width of windings is 0.219 inch) I need to know how much UH is every of the windings ,,then i will use Erics formula and calculate how much turns is needed for a coil of 32cm (12.6 inch) Using my own coil calculator I get the following results: L1 = 6.375" (162mm) wire thickness = 0.36mm turns = 85 inductance = 6.4mH L2 = 3.937" (100mm) wire thickness = 0.36mm turns = 27 inductance = 406uH L3 = 3.188" (81mm) wire thickness = 0.23mm turns = 275 inductance = 26.3mH To wind a search coil with an L1 inside diameter of 320mm -> L1 = 320mm wire thickness = 0.36mm turns = 55 / 56 inductance = 6.33mH / 6.5mH L2 = 198mm wire thickness = 0.36mm turns = 17 / 18 inductance = 381uH / 425uH L3 = 160mm wire thickness = 0.23mm turns = 176 / 177 inductance = 26.2mH / 26.5mH ========== a coil for the ClassicIII 32cm DD So i ordered a coil housing from Mdetectors (without cover:confused: ) Transmitter coil has 90 turns 0.4mm wire (5mH). Receiver coil has 110 turns 0.