Recovery times in pulse NMR

The problem Broad lines in the frequency domain decay 

There are two parts to solving the receiver paralysis problem. One is to reduce the pulse feedthrough and the other is to make the receiver recover quickly. The feedthrough may be reduced by a well designed duplexer together with a set of crossed diodes shunting the receiver input. The commonly used crossed diodes limit the input to the amplifier to only about 0.5 volt and no less. A modification to reduce this threshold has been suggested by Stokes (1978). 

The receiver paralysis can be reduced by a better receiver design. The amplifier bandwidth must be wide enough 

For transmitters which do not have rapid ringdown, Spokas (1965) proposed a passive device which used two TV damper diodes in such a way that it presented a low impedance to the transmitter output for small outputs and high 

A novel suggestion by Hoult (1979) to make the transmitter pulse decay rapidly is to reverse the phase of the end of the transmitter pulse in order to cancel the ringing. This is attractive because no additional circuitry is needed. Most modern spectrometers already have the capability of phase 

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