Jeff,
I don't know the specifics of what you might be seeing at 25.5 MHz to 26.1 MHz,
but there's a pretty good general chart on
the use-distribution of the whole r.f. spectrum at:
http://www.ntia.doc.gov/osmhome/allochrt.pdf
Hmmm. According to that chart, part of the spectrum you're having problems with
is reserved for radio-astronomy. Maybe you
should talk with the SETI folks.
Good luck, and have fun,
Patrick Wheeler
Isis Pharmaceuticals pwheeler_at_isisph.com
2280 Faraday Avenue phone: 760 603 2409
Carlsbad, CA 92008 fax: 760 929 0036
On 08/08/2000 9:05:33 AM, Jeff Walton <jhwalton_at_ucdavis.edu> wrote:
> Dear All,
>
> We have a 45 cm horizontal bore imaging system operating at 26 MHz
> (0.6
> Tesla). The spectrometer is an old GE 2T CSI system (we are running
> on the
> lowband) retrofit with a Tecmag Libra. Recently, radio frequency
> interferance has plagued us. The amplitude of the interferance
> depends on
> which coil we use. The interferance appears to be frequency
> modulated. It
> appears whether or not there is sample in the coil and appears over
> the
> entire tuning range of the coil, 25.5 MHz to 26.1 MHz. I can
> terminate the
> coax with a 50 ohm resistor instead of the coil and it dissappears.
> Thus,
> it appears we are picking something up through the air.
>
> Question: Does anyone know if there are any commercial, two-way hand
> held,
> or ham radios that regularly transmit around 26 MHz? Also, if anyone
> can
> think of another mechanism by which we might get this sort of
> interferance,
> I am open to suggestions.
>
> Thanks!
>
> Jeff
>
>
> Jeffrey H. Walton
> Associate Research Physicist
> One Shields Ave.
> UCD NMR Facility, Bldg. MS1-D
> University of California
> Davis, CA 95616
> (530) 752-7794 (office)
> (530) 752-6480 (MS1-D lab)
> (530) 754-9064 (Cruess Hall lab)
> (530) 752-8109 (FAX)
> jhwalton_at_ucdavis.edu
> NMR Facility URL http://www.nmr.ucdavis.edu
>
>
>
Received on Tue Aug 08 2000 - 13:35:13 MST