archive: SETI Dry ice, LN2, etc.

SETI Dry ice, LN2, etc.

willcox@voicenet.com
Thu, 27 Aug 1998 19:01:02 +0600

SETIzens,

Today's Mystery is-

Randy Stegemeyer wrote:
*I wonder about some other practical considerations for cooling a
*preamp. What I am thinking about is the effect of cooling on the other
*parts of the amplifier besides the active device. I would think that
*tuned circuits, resistor, and capacitor values would all change.
(end quote)

This will make us pause, who consider cryogenic temps!
Two (possibly useful) thoughts:
1) Astronomers have lots of experience here.
2) I have dunked fast (~10ns) pulse amplifiers for nuclear spectroscopy
in the LN2, no problemos. Then only a 10% change in risetime, or a 30%
change in amplitude, or total failure would show. And of course such
amps are not tuned RF amps! Importantly they did not reflect any
change in behavior in the data. (warm to cold to warm)

I'll try it Randy, but I don't have the aforementioned expensive HP noise
figure meter ;-(

John Willcox
40 00 00 N
75 30 30 W

Project Argus Observatory FN20fa