RF Switches

James C. Johnston (James.C.Johnston@lerc.nasa.gov)
Thu, 05 Dec 1996 16:56:11 -0500

I've got an AM 300 set up to do solids. We've recently replaced our Amplifier
Research 200L (tube type) amp with an AR 250A250 solid-state amp. The noise
in our spectra is overwhelming the data with the new amp. I've measured the
noise levels when the amp is not being pulsed, and those levels are between
10 and 100X bigger than the old amp.

I would like to install some kind of High-speed RF switch on the output of
the amp that could be used to switch the probe and amplifier through 50 Ohms
to ground during acquisition. Two SPDT switches would do the job, but they
would have to survive putting the RF pulses through them.

I would also like to use a similar solution to allow me to rapidly switch in
an attenuator on the decoupler's input - we would want to do tune up the
Hartmann-Hahn condition with the attenuator in so we could break H-H during
things like TOSS pulses.

Does anybody have a source for (or ideas about) rf switches and, if so,
could you point me in the right direction?

Thanks,
Chris

J. Chris Johnston
Polymers Branch, Materials Division (216) 433-5029
NASA Lewis Research Center (216) 433-5033 fax
21000 Brookpark Rd. MS 105-1 James.C.Johnston@lerc.nasa.gov
Cleveland, OH 44135
Resistance is Futile!