[Amps] FW: Water cooling

[Bill Fuqua]

Yes, the cavity half maybe easy but the other half much more difficult.
However, I am not sure the other half is that much of an improvement over
using a flat plate.
For some, who are seeking PERFECTION this could be their answer.
Or just don't have the tools, patients or skills to drill a lot of overlapping
holes in a block of copper or aluminum.
   Take the information for what it is. Possible source or
alternate idea of how to make your own.

73
Bill wa4lav


At 02:59 AM 8/23/2011 -0400, Roger (sub1) wrote:



>On 8/23/2011 12:21 AM, Fuqua, Bill L wrote:
> > here is a better link
> > http://www.customthermoelectric.com/Water_blocks.html
>
>Wayy too expensive for a decent size. You can make them with just a
>drill press and a bit of care. Even multi channel are not that difficult
>In a solid state system the heat sink can be at ground potential.
>
> >
> > ________________________________________
> >
> >
> > Here you go. If you want really effecient heat transfer use one of 
> these heat sinks.
> > 
> http://www.customthermoelectric.com/Accessories/images/Water_block_3x3x625_opn_400.jpg
>
>The top is gasketed in place, but the baffles are not sealed to the top
>allowing for cross leakage and erosion. That particular one looks like a
>poor design compared to the others.
>
> > 73
> >
> >
> >> If you want to look at what would be extreme compared to most
> >> electronic applications, just look at a car engine.
> > Yes, I have been thinking a lot about car engines. But it's hard to
> > translate that to my amplifier! In car engines the thermal power is far
> > larger, but also the allowable thermal gradient is far larger, the flow
> > rate is far larger, the contact area is far larger, and worst of all, I
> > don't really know how much contact area a car engine has! I really would
> > need to take apart one, cut open both the block and the cylinder head,
> > and measure them!
>
>Even if you could section one it would be very difficult to measure the
>surface area for heat exchange.
>Plus they are generally nodular iron and the system runs under
>pressure..  You can Measure the volume in the
>head and block but they are extremely crude compared to the precision of
>a cooler for a power FET.
> >
> > I just looked up values for solders: Common 60/40 solder conducts heat
> > about one fifth as well as copper,
>This is the reason we use heat transfer compounds like Artic Silver
>
> >
> > In a catalog from an aluminium supplier I found some extrusion stock
> > that looks much like an Omega sign, but closed. Like a round tube
>
>I'd stick with solid copper with a machined water way and a cover silver
>soldered on
>rather than one with a removable cover.
>
> > m here?
> > That's no issue for me. It would go into a closed container under the
> > desk, holding maybe 20 liters of water.
>
>Find for casual operating, but what about contesting.
>
> >
> > By simply letting the water in the bucket stay at grid potential too, I
> > can easily avoid tripping the ground fault interrupter, but the water
> > will be exposed to the full drain-to-drain RF voltage, which will be
> > like 140V RMS at full power. I measured the resistivity of my spring
> > water, and found that the water in the short hose running from one
> > MOSFET group to the other would have a resistance like 200 kiloohms, so
>
>You are looking for ohms per CM^3 or were you just measuring the
>resistance between two probes?
>It's rare to find tap, well, or spring water with more than a few
>hundred ohms per cubic CM.
>
>
>73
>
>Roger (K8RI)
> > in principle that's a non-issue too. But if over time the water
> > contaminates with metal ions, that could be bad news! Talk about a
> > slowly growing dummy load built into the amp! ;-)
> >
> > Manfred.
> >
> >
> > ========================
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> > http://ludens.cl
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