WW8J Link Coupled Tuner Coil Design
From VE3ERP Hamcalc Software Program
And
W4RNL Recommended Link Coupled Tuner Component Values
I have had several requests for design information of the LCT plug-in coil sets. I would like to say that the design I have chosen is based upon the layout of the tuner, as well as readily available materials (including coil forms) and components on hand, as well as the 0.25" copper tubing used for the inductors L1 & L2 coil set.
It is not necessary to clone the coil design specifications shown below in order to achieve the same values. For example, a coil set for 40 meters, L2 with a True inductance of 12uH could be wound with 7 turns of 0.25" copper tubing on an 8.0" form in order to provide an approx. 12 uH value for L2. This particular coil would not work with my tuner design because the male plug-in pins would not align to the female mounting receptacle. The physical properties of any given value inductor can be manifold.
In my design the 12 turns of 0.25" copper tubing for L2 (40 Meters) was chosen to accommodate the length of the female plug-in support. In fact, the length of all three coil sets vary from approx. 6.0-9.5 inches. You may have a different layout for your tuner, or may desire a different value for coil Q, and therefore the use of the free Hamcalc software program would be valuable in designing your coil sets. In the design of each of my coil sets, I have found that the derived Hamcalc software arithmetic values matched very closely the actual measured inductance meter values of the finished coil sets.
You do not need an inductance meter to build these coil sets! The information given in the tables below was derived from Hamcalc software available from George Murphy VE3ERP, and was used in the design of the Link Coupled Tuner shown on the previous web page.
|
40 meter Link Coupled L2 – L1 COIL SPECS
L2 Specs
True inductance.........................= 12.000 uH Number of turns........................= 12.000 Coil form diameter...................fd= 12.700 cm. = 5.000 in. Coil pitch diameter...................d= 13.335 cm. = 5.250 in. Wire diameter.........................W= 0.635 cm. = 0.250 in. Pitch (c.c. spacing of turns)........Sw= 1.250 cm. = 0.492 in. Coil Length...................Lcm, Lgth= 15.002 cm. = 5.906 in. Coil Length/diameter ratio...........Ld= 1.13:1 Wire diameter/spacing ratio........W/Sw= 0.51:1 Turns per inch (25.4mm).............Tpi= 2.032 Self-Capacitance.....................Co= 8.960 pF Added capacity required to resonate..Cx= 34.118 pF Frequency.............................ƒ= 7.000 MHz Self-Resonant frequency..............ƒs= 15.349 MHz Apparent inductance................La= 15.151 µH True reactance at resonance...........X= 527.788 ohms Apparent reactance at resonance....Xa= 666.397 ohms Total true resistance................Rc= 0.278 ohms Apparent total resistance..........Rt= 0.444 ohms True Q...............................Qt= 1897 Apparent Q.........................Qc= 1502
L1 COIL SPECS
True inductance.........................= 1.200 uH Number of turns........................= 3.015 Coil form diameter...................fd= 10.160 cm. = 4.000 in. Coil pitch diameter...................d= 10.795 cm. = 4.250 in. Wire diameter.........................W= 0.635 cm. = 0.250 in. Pitch (c.c. spacing of turns)........Sw= 1.270 cm. = 0.500 in. Coil Length...................Lcm, Lgth= 3.829 cm. = 1.507 in. Coil Length/diameter ratio...........Ld= 0.35:1 Wire diameter/spacing ratio........W/Sw= 0.50:1 Turns per inch (25.4mm).............Tpi= 2.000 Self-Capacitance.....................Co= 7.153 pF Added capacity required to resonate..Cx= 423.634 pF Frequency.............................ƒ= 7.000 MHz Self-Resonant frequency..............ƒs= 54.323 MHz Apparent inductance................La= 1.220 µH True reactance at resonance...........X= 52.779 ohms Apparent reactance at resonance....Xa= 53.670 ohms Total true resistance................Rc= 0.054 ohms Apparent total resistance..........Rt= 0.055 ohms True Q...............................Qt= 984 Apparent Q.........................Qc= 968 |
|
80 – 75 Meter Link Coupled L2 – L1 COIL SPECS
L2 COIL SPECS
True inuctance.........................= 22.000 uH Number of turns........................= 15.000 Coil form diameter...................fd= 15.240 cm. = 6.000 in. Coil pitch diameter...................d= 15.875 cm. = 6.250 in. Wire diameter.........................W= 0.635 cm. = 0.250 in. Pitch (c.c. spacing of turns)........Sw= 1.215 cm. = 0.478 in. Coil Length...................Lcm, Lgth= 18.225 cm. = 7.175 in. Coil Length/diameter ratio...........Ld= 1.15:1 Wire diameter/spacing ratio........W/Sw= 0.52:1 Turns per inch (25.4mm).............Tpi= 2.091 Self-Capacitance.....................Co= 10.948 pF Added capacity required to resonate..Cx= 83.042 pF Frequency.............................ƒ= 3.500 MHz Self-Resonant frequency..............ƒs= 10.255 MHz Apparent inductance................La= 24.900 µH True reactance at resonance...........X= 483.805 ohms Apparent reactance at resonance....Xa= 547.587 ohms Total true resistance................Rc= 0.301 ohms Apparent total resistance..........Rt= 0.386 ohms True Q...............................Qt= 1605 Apparent Q.........................Qc= 1418
L1 COIL SPECS
True inductance.........................= 2.200 uH Number of turns........................= 3.5000 Coil form diameter...................fd= 13.335 cm. = 5.250 in. Coil pitch diameter...................d= 13.970 cm. = 5.500 in. Wire diameter.........................W= 0.635 cm. = 0.250 in. Pitch (c.c. spacing of turns)........Sw= 1.921 cm. = 0.756 in. Coil Length...................Lcm, Lgth= 7.684 cm. = 3.025 in. Coil Length/diameter ratio...........Ld= 0.55:1 Wire diameter/spacing ratio........W/Sw= 0.33:1 Turns per inch (25.4mm).............Tpi= 1.322 Self-Capacitance.....................Co= 6.882 pF Added capacity required to resonate..Cx= 933.018 pF Frequency.............................ƒ= 3.500 MHz Self-Resonant frequency..............ƒs= 40.904 MHz Apparent inductance................La= 2.216 µH True reactance at resonance...........X= 48.381 ohms Apparent reactance at resonance....Xa= 48.737 ohms Total true resistance................Rc= 0.044 ohms Apparent total resistance..........Rt= 0.044 ohms True Q...............................Qt= 1107 Apparent Q.........................Qc= 1098 |
|
160 meter Link Coupled L2 – L1 COIL SPECS
L2 COIL SPECS
True inductance.........................= 42.000 uH Number of turns........................= 18.000 Coil form diameter...................fd= 20.320 cm. = 8.000 in. Coil pitch diameter...................d= 20.955 cm. = 8.250 in. Wire diameter.........................W= 0.635 cm. = 0.250 in. Pitch (c.c. spacing of turns)........Sw= 1.328 cm. = 0.523 in. Coil Length...................Lcm, Lgth= 23.911 cm. = 9.414 in. Coil Length/diameter ratio...........Ld= 1.14:1 Wire diameter/spacing ratio........W/Sw= 0.48:1 Turns per inch (25.4mm).............Tpi= 1.912 Self-Capacitance.....................Co= 13.363 pF Added capacity required to resonate..Cx= 172.780 pF Frequency.............................ƒ= 1.800 MHz Self-Resonant frequency..............ƒs= 6.718 MHz Apparent inductance................La= 45.248 µH True reactance at resonance...........X= 475.009 ohms Apparent reactance at resonance....Xa= 511.745 ohms Total true resistance................Rc= 0.313 ohms Apparent total resistance..........Rt= 0.363 ohms True Q...............................Qt= 1517 Apparent Q.........................Qc= 1408
L1 COIL SPECS
True inductance.........................= 4.200 uH Number of turns........................= 4.000 Coil form diameter...................fd= 18.415 cm. = 7.250 in. Coil pitch diameter...................d= 19.050 cm. = 7.500 in. Wire diameter.........................W= 0.635 cm. = 0.250 in. Pitch (c.c. spacing of turns)........Sw= 1.259 cm. = 0.496 in. Coil Length...................Lcm, Lgth= 5.035 cm. = 1.982 in. Coil Length/diameter ratio...........Ld= 0.26:1 Wire diameter/spacing ratio........W/Sw= 0.50:1 Turns per inch (25.4mm).............Tpi= 2.018 Self-Capacitance.....................Co= 12.723 pF Added capacity required to resonate..Cx= 1848.703 pF Frequency.............................ƒ= 1.800 MHz Self-Resonant frequency..............ƒs= 21.772 MHz Apparent inductance................La= 4.229 µH True reactance at resonance...........X= 47.501 ohms Apparent reactance at resonance....Xa= 47.828 ohms Total true resistance................Rc= 0.064 ohms Apparent total resistance..........Rt= 0.065 ohms True Q...............................Qt= 747 Apparent Q.........................Qc= 742 |