Electrical apparatus for measurement of moisture content by measurement of radio frequency power absorption utilizing a power limiting capacitor

Claim 2

A continuous and static moisture testing instrument for particulate materials comprising the combination of a test cell having a housing for receiving the particulate material and having a portion thereof connected to electrical ground, a radiating element aligned within said housing, a radio frequency power circuit including radio frequency oscillating generator means electrically connected through an isolating capacitor to the radiating element for supplying radio frequency power thereto, a measuring circuit including an indicating device connected between the oscillating generator means and the electrical ground and capable of indicating the amount of radio frequency power being absorbed in the test cell, and a coupling capacitor connected between said oscillating generator means and said indicating device for preventing the power supplied to said measuring circuit from exceeding a predetermined value.

Claim 3

A continuous and static moisture testing instrument for particulate materials comprising the combination of a test cell having a housing for receiving the particulate material and having a portion thereof connected to electrical ground, a radiating element aligned within said housing, a radio frequency power circuit including radio frequency oscillating generator means electrically connected through an isolating capacitor to the radiating element for supplying radio frequency power thereto, a measuring circuit including an indicating device connected between the oscillating generator means and the electrical ground and capable of indicating the amount of radio frequency power being absorbed in the test cell, and a coupling capacitor connected between said oscillating generator means and said indicating device for preventing the power supplied to said measuring circuit from exceeding a predetermined value.

Claim 4

A continuous and static moisture testing instrument for particulate materials comprising the combination of a test cell having a housing for receiving the particulate material and having a portion thereof connected to electrical ground, a radiating element aligned within said housing, a radio frequency power circuit including radio frequency oscillating generator means electrically connected through an isolating capacitor to the radiating element for supplying radio frequency power thereto, a measuring circuit including an indicating device connected between the oscillating generator means and the electrical ground and capable of indicating the amount of radio frequency power being absorbed in the test cell, and a coupling capacitor connected between said oscillating generator means and said indicating device for preventing the power supplied to said measuring circuit from exceeding a predetermined value.

Claim 5

The moisture testing instrument according to claim 1 including a transistor in the radio frequency power circuit and wherein said isolating capacitor is a DC voltage blocking capacitor connected between the radiating element and the transistor.

Claim 6

The moisture testing instrument according to claim 1 wherein the radio frequency power circuit is composed of a transistor having a feed back capacitor connected between the collector terminal and the emitter terminal of said transistor and an inductance means and an adjustable capacitor means connected in parallel between the collector terminal of the transistor and the circuit ground to set the operating frequency of the radio frequency power circuit at a predetermined value.

Claim 7

The moisture testing instrument according to claim 1 wherein the test cell comprises a cylindrical housing and said radiating element is coaxially aligned within the cylindrical housing.

Claim 8

Apparatus for measuring the radio frequency power absorbance of a test material comprising: a solid state electronic oscillator consisting of a single transistor and a tuned circuit composed of an inductor and capacitor, at least one of said inductor and capacitor being variable to allow adjustment of the resonant frequency of the tuned circuit, a test cell composed of a radiating element electrically connected through an isolating capacitor to the collector terminal of the electronic oscillator and located adjacent to a reference element electrically connected to the circuit ground, and means for sensing and indicating the power output of the electronic oscillator which decreases in proportion to the amount of power absorbed by the material in the test cell and a coupling capacitor connected between the electronic oscillator and the indicating means for preventing the power supplied to said indicating means from exceeding a predetermined value.

Claim 9

Apparatus for measuring the radio frequency power absorbance of a test material comprising: a solid state electronic oscillator consisting of a single transistor and a tuned circuit composed of an inductor and capacitor, at least one of said inductor and capacitor being variable to allow adjustment of the resonant frequency of the tuned circuit, a test cell composed of a radiating element electrically connected through an isolating capacitor to the collector terminal of the electronic oscillator and located adjacent to a reference element electrically connected to the circuit ground, and means for sensing and indicating the power output of the electronic oscillator which decreases in proportion to the amount of power absorbed by the material in the test cell and a coupling capacitor connected between the electronic oscillator and the indicating means for preventing the power supplied to said indicating means from exceeding a predetermined value.

Claim 10

The apparatus according to claim 5 wherein the sensing and indicating means comprises a variable resistor a semiconductor diode and an indicating device interconnected across the oscillator from the emitter terminal of the transistor to circuit ground.