Dear NMR friends:
Recently we have a strange and strong RF radiation interference
centered at 75.438 MHz which is picked up by our Mercury 300 probe with
C13 resonance at 75.464 MHz. The Mercury 300 NMR spectrometer is located
at 6th floor. The RF signal is intermittent, stays on for about few
seconds to more than 20 seconds and off for few second to more than 20
seconds., its profile and intensity change also. Some outside agents
came with RF devices to check the source of it, and could not tell
where it was from.
We are told that a pager service tower is at 25 miles away which
radiates RF signal at 75.44 MHz. It might be the source. However, this
tower has been there for many years and we did not have the problem
until recent two months.
If the RF signal continues and we can not locate the source, the
option we have is to shield the spectrometer by Farady cage or move it
to first floor at which we did not detect the RF signal.
Does anyone have such experience and how to solve it?
Thank you for your help.
Hongjun Pan
Received on Wed May 25 2005 - 23:34:45 MST