[R-390] R-390 Cooling Fan

[Dan Merz]

Hi,  yes I'm happy with the fan I put on my 390.  About the cryo-treated
tubes - yes razor blades, tools steels and other metals that rely on
martensitic transformations benefit from cryo treatment to convert all the
material to the hard martensitic phase.  Offhand, I know of no instance
where such treatment affects the grain structure of metals, other than
effecting a phase change.  I don't believe such metals are used in tubes
What could possibly come from quenching a tube to cryo temperatures?  Gases
condense but vaporize again upon heating.  Metals contract but expand again
upon heating,  in itself not a good idea where glass to metal seals are
involved.  Thermal cycling to cryo temperature is a way to weed out parts,
designs and materials that may later fail and it is an accepted method for
acceptance testing of some devices and materials that might need high
reliability.  So a tube that survives a cryo test might be superior to one
that doesn't but I doubt that the cryo cycling itself improves a tube other
than getting rid of the "bad" ones.  But stranger things happen !!  I'll
stick to the ones that have set around at room temperature.  Besides,  I
don't have any liquid nitrogen around to try it.  Dan.   

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Roy Morgan
Sent: Thursday, July 21, 2005 10:13 AM
To: Craig C. Heaton; R-390 at mailman.qth.net
Subject: Re: [R-390] R-390 Cooling Fan

At 12:10 PM 7/21/2005, Craig C. Heaton wrote:
>Good Morning to All:
>
>And my $0.02 worth.................I have several hundred cryogenically 
>treated orange drop (715 style) capacitors with years worth of 
>refrigeration stored in them

Craig,

Have you seen the websites that actually offer cryogenically treated audio
tubes?

No s**t.

Only a hundred dollars or so each. 12AX7's, 6L6's and even a pair of KT-88's
if I remember right.  Astounding prices.

<http://www.physicsforums.com/archive/t-59273_Cryogenically_Treated_Vacuum_T
ubes.html>
is a discussion

<http://vacuumtubeaudio.com/cat8_1.htm>
has tubes for sale

<http://www.metal-wear.com/electronics_$_stereos.htm>
is an explanation from a company that does such treatments on parts. They
mention reports about missile parts, electronic circuit boards, and other
things that were improved by such treatments.

 From my Google search, it appears that some folks who own and/or
manufacture and sell firearms believe that cryogenic treatment of gun
barrels and shotgun chokes improves them.  This I can understand.  Vacuum
tubes?  No, I don't understand.

Roy

Whose freezer is * not* big enough for the GPT-750 transmitter, but might
hold a McIntosh amplifier or two.


- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan at nist.gov --

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