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LCT Coil Set Design

 

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 sets.

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. 

As previously mentioned, this tuner was designed for 160 - 20 meters   The specifications below do not include the 20 meter coil.  I will be publishing the 20 meter coil specification at a later date.

 

 

 

WW8J Link Coupled Matching Network Specifications

 

 

40 meter Link Coupled L1 L2 COIL SPECS

                   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.............................= 7.000 MHz

Self-Resonant frequency..............s= 54.323 MHz

Apparent inductance................La= 1.220 H

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

 

                   L2  Coil 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.............................= 7.000 MHz

Self-Resonant frequency..............s= 15.349 MHz

Apparent inductance................La= 15.151 H

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

 

 

 

80 75 Meter Link Coupled L1 L2 COIL SPECS

                   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.............................= 3.500 MHz

Self-Resonant frequency..............s= 40.904 MHz

Apparent inductance................La= 2.216 H

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

 

                  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.............................= 3.500 MHz

Self-Resonant frequency..............s= 10.255 MHz

Apparent inductance................La= 24.900 H

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

 

 

                  

160 meter Link Coupled L1 L2 COIL SPECS

                    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.............................= 1.800 MHz

Self-Resonant frequency..............s= 21.772 MHz

Apparent inductance................La= 4.229 H

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

 

                   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.............................= 1.800 MHz

Self-Resonant frequency..............s= 6.718 MHz

Apparent inductance................La= 45.248 H

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

 

 

 

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Page last updated on 01/18/2011

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