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The RF high power amplifier is a key module in the NMR spectrometer. Robustness, lower power consumption, and small size are requirements. In this thesis, devices are studied and different design approaches are considered. New ideas are introduced, and simulations are used to show if it these work. A real prototype is developed. Results from the prototype are satisfactory and in good agreement with the simulation results. This allows for the possibility of a real portable NMR spectrometer 'Lapspec'. Points of note: • Feedback to stabilize amplifier, • Hard bias to improve rise time of pulse, • A rugged device is chosen, • Power limiter technology is used to avoid overdrive amplifier, • Lower value attenuator at output of final stage to reduce load VSWR, • Reason of spike is studied, the solution to reduce spike is given, • The reason of instability of amplifier with NMR load is analyzed, • A method is introduced to ensure there is no oscillation while the High Power Amplifier (HPA) is connected with the NMR probe.

Acquire solids nuclear magnetic resonance (solids-NMR) capability to enable characterization of polymers and other solid state materials of relevance to DoD. Instrumentation Acquired: A solids-NMR accessory was acquired for an existing Bruker AC 250 (1H resonance at 250 MHz) liquids-NMR spectrometer. The acquired equipment included: (a) 35 W buffer amplifier, (b) 120 W radio frequency (RF) amplifier for 1H decoupling, (c) 300 W broadband rf amplifier for non-1H nuclei, and (d) 7 mm sample diameter (0.300 ml sample volume) cross polarization magic angle spinning (CP MAS) probe with pneumatic control unit. The apparatus was installed and tested by specialists from Bruker Instruments, Billerica, MA. Research Supported by Instrumentation: The first solid sample investigated using the newly acquired apparatus was the monomer 1,5,7,11 tetraoxospiro 5,5 undecane, commonly called spiroorthocarbonate(0,0). This is an example of a monomer that polymerize without reduction in volume. Research to be Supported by Instrumentation: Solids-NMR will be used to help determine the structures of organic polymers and inorganic solid state materials of relevance to DoD. The polymers include ladder- and semi ladder shaped highly conjugated polymers and their monomers, and polyurethane coating materials. The inorganic solids include catalytic zeolites and ferrierites. Relevant nuclei are: 27 Al (65 MHz), 13C (63 MHz), 29Si (50 MHz) and 15N (25 MHz).

Sensitivity is one of the fundamental parameters of the Nuclear Magnetic Resonance experiment. It depends particularly on the coil and impedance matching of the resonance circuit of the probe to the input amplifier. However, sensitivity is also influenced by the noise of the receiver of the spectrometer, and the insertion loss of the matching and switching circuits as well as of passive fillers inserted in front of the input preamplifier manifests itself markedly. In this paper, a simple method of measuring the noise figure feasible in the NMR laboratory is described. Using non-standard probes and coils, the measurement of the noise figure enables one to estimate to what degree the detection system itself participates in the signal/noise ratio deterioration. The method can be used also for measurements of other radio-frequency signal processing systems.

Sensitivity is one of the fundamental parameters of the Nuclear Magnetic Resonance experiment. It depends particularly on the coil and impedance matching of the resonance circuit of the probe to the input amplifier. However, sensitivity is also influenced by the noise of the receiver of the spectrometer, and the insertion loss of the matching and switching circuits as well as of passive fillers inserted in front of the input preamplifier manifests itself markedly. In this paper, a simple method of measuring the noise figure feasible in the NMR laboratory is described. Using non-standard probes and coils, the measurement of the noise figure enables one to estimate to what degree the detection system itself participates in the signal/noise ratio deterioration. The method can be used also for measurements of other radio-frequency signal processing systems.

Sensitivity is one of the fundamental parameters of the Nuclear Magnetic Resonance experiment. It depends particularly on the coil and impedance matching of the resonance circuit of the probe to the input amplifier. However, sensitivity is also influenced by the noise of the receiver of the spectrometer, and the insertion loss of the matching and switching circuits as well as of passive fillers inserted in front of the input preamplifier manifests itself markedly. In this paper, a simple method of measuring the noise figure feasible in the NMR laboratory is described. Using non-standard probes and coils, the measurement of the noise figure enables one to estimate to what degree the detection system itself participates in the signal/noise ratio deterioration. The method can be used also for measurements of other radio-frequency signal processing systems.

Sensitivity is one of the fundamental parameters of the Nuclear Magnetic Resonance experiment. It depends particularly on the coil and impedance matching of the resonance circuit of the probe to the input amplifier. However, sensitivity is also influenced by the noise of the receiver of the spectrometer, and the insertion loss of the matching and switching circuits as well as of passive fillers inserted in front of the input preamplifier manifests itself markedly. In this paper, a simple method of measuring the noise figure feasible in the NMR laboratory is described. Using non-standard probes and coils, the measurement of the noise figure enables one to estimate to what degree the detection system itself participates in the signal/noise ratio deterioration. The method can be used also for measurements of other radio-frequency signal processing systems.

Sensitivity is one of the fundamental parameters of the Nuclear Magnetic Resonance experiment. It depends particularly on the coil and impedance matching of the resonance circuit of the probe to the input amplifier. However, sensitivity is also influenced by the noise of the receiver of the spectrometer, and the insertion loss of the matching and switching circuits as well as of passive fillers inserted in front of the input preamplifier manifests itself markedly. In this paper, a simple method of measuring the noise figure feasible in the NMR laboratory is described. Using non-standard probes and coils, the measurement of the noise figure enables one to estimate to what degree the detection system itself participates in the signal/noise ratio deterioration. The method can be used also for measurements of other radio-frequency signal processing systems.

Sensitivity is one of the fundamental parameters of the Nuclear Magnetic Resonance experiment. It depends particularly on the coil and impedance matching of the resonance circuit of the probe to the input amplifier. However, sensitivity is also influenced by the noise of the receiver of the spectrometer, and the insertion loss of the matching and switching circuits as well as of passive fillers inserted in front of the input preamplifier manifests itself markedly. In this paper, a simple method of measuring the noise figure feasible in the NMR laboratory is described. Using non-standard probes and coils, the measurement of the noise figure enables one to estimate to what degree the detection system itself participates in the signal/noise ratio deterioration. The method can be used also for measurements of other radio-frequency signal processing systems.