This is an excerpt from Varian VNMR News dated 11-18-2001.

On UNITYplus and earlier instruments, the receiver was ON by default, hence in pulse sequences that started off with an r.f. pulse on the observe channel on a strong sample, or whenever there is a large transverse magnetization in the course of a pulse sequence, one could get a receiver overflow. Also homo-gated decoupler presaturation on H2O samples would immediately generate receiver overflow. The remedy for this was to start a pulse sequence with "rcvroff()" (receiver off), together with a "rcvron()" (receiver on) just prior to acquisition. This avoids receiver overflow, but leaves the amplifiers unblanked all the time, which in long pulse sequences might lead to pulse droop and amplitude instabilities towards the end of the sequence, which in turn could lead to bad cancellation in experiments that do signal subtraction by phase cycling. The only (proper) alternative on these instruments was to leave the receiver on (except around the pulses), and to IGNORE the receiver overflow LED / message.

On UNITY INOVA, the receiver is Print this page.

Now stop crying and get back to work!