[Amps] Solid state amplifier cooling

[Fuqua, Bill L]

  You would may need to keep a small vacuum on the water to assure that it 
vaporizes at a sufficiently low temperature. Also, most vapor phase anodes have
cubes or bumps on their surfaces to facilitate the boiling of the water. The 
solid state devices are derated at starting at much lower temperatures than
water boils. Works well in tubes where the seal temp. limit is ofter around 200 degrees C.

73
Bill wa4lav


________________________________________
From: Amps [amps-bounces at contesting.com] on behalf of Jim Thomson [jim.thom at telus.net]
Sent: Thursday, June 06, 2013 12:44 PM
To: amps at contesting.com
Subject: [Amps] Solid state amplifier cooling

Date: Thu, 6 Jun 2013 09:15:54 -0600
From: MU 4CX250B <4cx250b at miamioh.edu>
To: amps at contesting.com
Subject: Re: [Amps] Message-ID: <963402869080783179 at unknownmsgid>
CSolid state amplifier cooling

Interesting idea, Bill. I wonder if folks on the reflector have tried
vapor phase cooling? In principle, that should be the most effective
cooling scheme of all, given the high latent heat of vaporization of
water. Of course, the devil is in the details, and the practicalities
might be too burdensome. This is an interesting discussion.

Jim w8zr

##  Vapour phase is not as good as you think it is. If u look at any old paper copy
of eimacs care and feeding, re vapour phase cooling., you will see that the max effect
occurs at 135 C..and not 100 C.   That entire section is not in the latest online version,
too bad.   100 C is too high for SS devices..and 135 C is clearly way too much.

##  Then you also have the problem with bubbles forming on the surface of
what ever you are trying to cool.   Tubes made for vapour phase cooling
have rough surfaces, to break up the bubbles.

##  Eimac sez that forced air is good for 50 w per sq cm of anode area.   And  135 W
for vapour phase cooling.  Water cooling is the best at 1000 w per sq cm.

##  the ultimate setup   is multiphase cooling..a combo of water-vapour- then back to water
cooling.   But that would be difficult to implement on a SS device.

##  Plane water cooling would be the easiest to implement.   Schemes using freon would also work,
but as others have noted, then u have condensation problems..and ditto with vapour phase cooling.

Jim  VE7RF

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