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The LC31 3.1 MHz Link Coupler for Plasma Tubes

Information current as of 03 December, 2017

LC31S shown, LC31P similar.


LC31S, TCP (blue,) TCS (green) coaxial tuning capacitors and LC31 coil assembly


The LC series of plasma tube couplers has been specially designed to work with the SSQ-2F v3.21, the PA1, PA2, PA3 and the SPA4 amplifiers.

The use of an LC31 coupler is required when driving a plasma tube with any of our amplifiers or with the SSQ-2F.

The LC coupler system will work with most of the Bill Cheb plasma tubes, including the Cheb 4, 5 and 8 inch Phanotron tubes, the Cheb SSQ-PT, SSQ-ST, SSQ-BAT, the 7 inch x 18 mm diameter Quartz Ar/He and Ne/Ar tubes, and the Original Cheb 2" x 26" Super Tube. 

Using the LC coupler allows you to to efficiently feed RF power to your plasma tube while maintaining excellent signal quality.


Using the LC31P or the LC31S is easy. Simply connect one end of a 23 foot / 7 meter length of 50 ohm coaxial cable to the RF OUT connection on the SSQ-2F v3.21, the PA1, the PA2 or the PA3 amplifier. Connect the other end of the coaxial cable to the input terminals of the LC coupler assembly. Connect two insulated wires from the output terminals of the LC coupler to the electrodes of your plasma tube. That's it! Now, power up your system. No tuning is required.

A heavy-enamel insulated 18 gauge copper wire secondary coil is wound directly on a sturdy PVC coil form. This coil will connect to your plasma tube. A primary winding of 14 gauge PVC insulated wire is then wound over the center of the secondary coil. The primary coil accepts the RF power from the SSQ-2F v3.21, the PA1, the PA2 or the PA3. Two Mica capacitors allow tuning of the primary winding for maximum power transfer. A high voltage coaxial capacitor is then connected across the terminals of the secondary coil. This capacitor tunes the secondary coil to match your plasma tube. Should you decide to use a different plasma tube, the coaxial tuning capacitor may be easily removed and replaced with a different one. Screw terminal connector blocks are used for all electrical connections to the LC coupler. There are no wires to solder.

If you wish to use the LC coupler with several different plasma tubes, you only need to make a few simple adjustments to use the LC31 with your the new plasma tube. In order to switch the LC coupler for use the other tube, you simply swap the TC coaxial capacitors and move one jumper on the input terminal block on the LC coupler. The time required to make the change is approximately 1 minute.

The price of the LC31 coupler including the required capacitors for use with your choice of Bill Cheb's plasma tubes is $85.00.

When ordering any LC31 coupler. please be sure to send us an email or place a note on your order and let us know exactly which plasma tube you will be using so that we can be sure to send you the right coupler for your plasma tube

For complete technical details and ordering information for the LC31 couplers, please click here.

Please refer to the instruction manual for further details.


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