Howdy all,
Glenn Facey [mailto:gafacey_at_science.uottawa.ca]
wrote on: Monday, November 03, 2003 10:54 AM
> There are a number of grounding springs to the probe
> case broken off. Could that be it?
A good electrical connection of the upper and lower stacks are VERY
important in keeping out external RF interference. With a good
electrical connection there is an RF shielded region near the sample.
Without a connection you have an antenna bring in external noise to the
sample region.
Blurts of noise in the spectrum baseline usually come from preamp
overload. When the preamp is overloaded its performance is non-linear.
When response is non-linear you have a mixer and get a lot of sum and
difference frequencies. The overload need not be at a frequency where
you are looking. Take a look at the preamp output with a scope and see
if it has an output when not running spectra. If your scope cannot see
that high a frequency then use/make a detector probe to see if there is
any RF output from the preamp when there should not be any.
woody_at_acornnmr.com
Received on Tue Nov 04 2003 - 17:19:44 MST