Abstract: Methods for using nutritional supplements containing lipoic acids and sulfur containing compounds to maintain or increase the levels of cellular GSH in the body are described. In some instances, the nutritional supplements can increase both the levels of GSH, vitamin C, GST activity, and antioxidant protection in the blood. The nutritional supplement contain a first part containing an effective amount of a lipoic acid and a second part containing an effective amount of a sulfur containing compound that increases the level of GSH vitamin C, GST activity, and antioxidant protection in the blood The first part and second part of the nutritional supplement can be partially or completely separated. The increased GSH and vitamin C levels increases the detoxification ability of the body as measured by the GST (Glutathione S-Transferases) activity and the antioxidant protection as measured by SAR (Serum Antioxidant Reserve). Other embodiments are described.

Abstract: Nutritional supplements and methods for making and using such supplements are described. In particular, this application describes nutritional supplements with a first part containing an effective amount of a lipoic acid (such as ALA) and a second part containing an effective amount of a sulfur containing compound that increases the level of cellular glutathione (such as NAC). The first and second parts are kept partially or completely separated from each other, thereby minimizing their reaction and maximizing their effectiveness. Such nutritional supplements can be administered to mammals to increase the levels of glutathione while maintaining or increasing the stability of these two components while they are contained in the supplement. Other embodiments are described.

Abstract: A method and apparatus for a sweep oscillator and a spectrum analyzer containing the sweep oscillator having a precisely determined center frequency includes a sweep circuit having a sawtooth waveform, a reference oscillator, a microprocessor controller and a modified phase-locked loop. The modified phase-locked loop further includes a control signal summer, a voltage controlled oscillator coupled to the control signal summer, a sweep oscillator output, and a sample and hold circuit including a switching circuit.

Abstract: Microprocessor (MPU) controlled voltage controlled oscillator (VCO) linearization circuitry locks the VCO at desired low, center and high frequencies (F.sub.1, F.sub.c and F.sub.h) and measures the magnitudes of the corresponding control voltages (V.sub.1, V.sub.c and V.sub.h). Next, the VCO is swept at a nominal clock frequency to determine the times (T.sub.1, T.sub.2 and T.sub.h) that the control voltages (V.sub.1, V.sub.c and V.sub.h) occur during the sweep cycle. The control voltage of the VCO is then swept at a first and then a second rate during a sweep cycle to assure that the center frequency (F.sub.c) of the VCO occurs at the time (T.sub.c) midpoint of the sweep cycle. As a result, each VCO frequency can be determined by MPU monitoring according to the time that the VCO frequency occurs during the sweep cycle. This circuitry is useful in spectrum analyzers for indirectly determining the otherwise unknown frequency of a received signal.

Abstract: An additional mixer is included in the feedback loop of a PLL which can be one of the local oscillators of a dual conversion system. A fine tuning frequency synthesizer is coupled to an input of the additional mixer for providing fine frequency control of the PLL. The fine tuning frequency synthesizer can include an additional phase locked loop. Also, a feedback signal for suppressing noise created by another local oscillator can also be applied to the additional mixer.

Abstract: A circuit which attenuates an RF signal in response to a voltage level of a control signal is disclosed. A first PIN diode resides in series with an RF signal path, and a second PIN diode shunts the RF signal path to ground. A first differential amplifier responsive to the control signal drives the first PIN diode, and a second differential amplifier responsive to the control signal drives the second PIN diode. Gain and maximum current output for each of the amplifiers are independently controlled. Additionally, separate reference voltage sources may apply to one input of each of the differential amplifiers.