Everyone:
I have a Varian VNMRS-500 NMR with 3 channels. Channel 3 in on one
amplifier (VN# 00-969441-06) and Channel 1 and 2 are on another
amplifier(VN#00-992254-04) I have a problem where the compression
values have changed. I measured the output from the amplifiers with
a scope, while changing power settings from the computer.
Problem #1:
The channel 3 amplifier is nice and linear, but the maximum output is
achieved at 60 dB. This explains the terrible compression value from
61-63 dB. Before we moved into our new location, the amplifier was
linear at 62 dB. Does anyone know why the amplifier would now put
out maximum output at a lower power setting?
Problem #2
The Channel 1 and 2 amplifier is not linear on either channel. It
also have maximum output at a lower setting (61 dB), but the
compression values are low (0.6-0.8) even at lower power
levels. What do I do about this?
Thanks for any help!
Susan
Susan L. Nimmo, Ph.D.
NMR Facility Manager
Department of Chemistry and Biochemistry
University of Oklahoma
101 Stephenson Parkway
Norman, Oklahoma 73019
office: 405-325-0677
cell: 405-627-7044
lab: 405-325-2843
Received on Wed Dec 14 2011 - 05:12:28 MST