Other

Metcal, Inc.

Eni Div. of Astec America, Inc.

Steven J Smith

Robert R Clappier

Roger M Smith

Yogendra K Chawla

A harmonic and subharmonic filter is coupled between a high power RF energy source and a non-linear RF load via a matching network, such as a plasma chamber. The filter passes high power RF energy in a band centered on a predetermined radio frequency, i.e., 13.56 MHz, but blocks and attenuates out-of-band energy at frequencies which are multiples of or fractions of the predetermined frequency. The harmonic and subharmonic filter comprises an input terminal, an output terminal, a series LC resonance path connected between the input and output terminals, and tuned to the predetermined radio frequency, a series resistive path formed of first and second resistors, and a parallel LC resonance path between the junction of the two resistors and ground.

Harmonic and subharmonic filter

The present invention achieves constant voltage at radio frequencies to drive a constant voltage to constant current converter, by employing a tightly coupled d.c. feedback loop to control the voltage via a transformer to the drain of a FET operated as a Class C amplifier in the saturated mode whereby among other advantages, the amplifier can withstand, without damage, very high VSWRs. Control is affected by a high gain differential amplifier which compares a d.c. voltage derived from the r.f. output of the system against a highly stable d.c. voltage reference. A controller, responding to the output of the differential amplifier causes a first level of voltage to be applied to the drain of the FET when the system is not loaded and causes a second voltage varying between said first level and a higher level when the system is loaded. In the lower voltage condition the controller is effectively removed from the system so that it does not have to drop a high voltage to a low voltage; the low voltage being supplied effectively from a separate source.

Constant current r.f. generator

A log splitter attachment for use with a garden tiller. The log splitter attachment is comprised of a frame portion which is releaseably attached to the roto-tiller drive shaft, a log splitting screw which is releaseably attached to the tiller drive shaft to allow for rotatable movement of said splitting screw in unison with the garden tiller drive shaft, and a log support bar attached to the frame portion and extending outwardly for ground engaging support to provide a log rest support during use, and to stabilize the frame portion and the tiller during use.

Growing community of inventors

Redwood City, CA, United States of America

Steven J Smith