Low-dissipation tunable rf preamplifier for low temperature NMR applications.
We describe a simple circuit which can be used as an impedance matching device to improve the S/N ratio when lossy cables must be used in low-temperature NMR experiments. The total dissipation is less than 2 mW and the circuit operates satisfactorily down to 1.5 K. The only tuned circuit is the nuclear resonance circuit which incorporates GaAs (P) diodes which can be tuned remotely.
Wampach
H R
HR
Service de Physique du Solide et de Résonance Magnetique, Centre d'Etudes Nucléaires de Saclay, BP no. 2, Gif-sur-Yyette, France.
Sullivan
N S
NS