Dear Ammrl friends:
About a month ago, I sent an email about strange RF radiation
interference on our Mercury 300 at 75.438 MHz. I received a lot of
responses with good suggestions. Thank you all for the great help and
suggestions. After followed many suggestions and more search, I finally
comfirmed that this intermittent pulses are from out side, not from NMR
instrument itself. I swapped a probe which is better shielded, the
detected intermittent signal is much smaller and does not cause the
receiver overflow. This signal is just outside of normal 13C spectrum
window (20 KHz away from the 13C center), so is not seen in normal 13C
spectrum.
However, I am very confident that this 75.438 MHz pulses is most
likely from the local pager service tower. Hope it will not cause
problems in the future.
Again, thank you all for reponses and suggestions.
Hongjun
Received on Tue Jun 21 2005 - 17:52:14 MST